# Capacitors Complete waste of money



## ccapehart1980 (Aug 6, 2013)

okay i recently read an article about capacitors on the web site 
and it was very well writtin and very convincing enough so that i canceled the cap i ordered and or ordered a hi amp alternator instead 

you guys check it out tell me what you think 
Car Audio CAPACITORS: Why They DON'T Work


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## Hertz5400LincolnLS (Mar 29, 2010)

A capacitor is not a substitute for a high output alternator and vice versa. Each serve their own purpose but some people don't understand the differences between the two.

Sent from my ADR6425LVW using Tapatalk 2


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## minbari (Mar 3, 2011)

some of what he says makes sence. the problem is its not a valve. it doesnt discharge, then recharge in two destinct steps. when the amplifier draws current, it draws from the cap and the battery and the alternator all at once. its not like it will deplete the cap then have to recharge it. he makes it sound like that it what it does, it doesnt.

that said. they do have limited uses. if you have a alternator that is not keeping up with charging the battery, then a cap will do nothing. you have to make more current, end of story. high output alt is the only solution.

if you have the dimming headlights problem it can be because of two reason. 

1) alternator is not keeping up and you dragging voltage down to battery level.
2) the alternator regulator does respond fast enough for the quick surges in current.

in the case of #2 your batteries will not go dead, but you still have dimming headlights. For that case, a cap will mask the problem (which is really not a problem)

they work good as a large filter cap if you have a noisey electrical system too.


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## ccapehart1980 (Aug 6, 2013)

yeah i decided to change out the wires from the alt to batt and ground to 0 guage wires 
and amazon has a 250 alt for my tahoe for like 140 bucks 

another question is 
is it recomended to just ad a second alt or replace the current one witha hi current one 
they make a kit so you can add a second alt in my tahoe is there any issues that will arise by adding a second one other then stealing a little bit more power off yer engine


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## minbari (Mar 3, 2011)

ccapehart1980 said:


> yeah i decided to change out the wires from the alt to batt and ground to 0 guage wires
> and amazon has a 250 alt for my tahoe for like 140 bucks
> 
> another question is
> ...


nope, just wire them in parallel.

just an FYI, a high output alt doesnt give you more power for free either. its takes more horsepower to turn than a stock one does. I think I read that the DC power 370 amp alt takes like 35hp to turn at full current.


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## ccapehart1980 (Aug 6, 2013)

also i dont understand why a cap wouldnt be beneficial because in all other applications a "bufferr" always helps or increases performance 
for example a large memory buffer in your computers hard drive increases performance as well as in a DVD burner streaming video buffereing allows for smooth video 

the idea behind a stiff cap seems sound 
Does a car stereo amp draw voltage steadily or doesnt it spike or lower depending one what its putting out to the speaekers sorry this mite be a dumb qeustion i slept alot in my electronics class at UTI


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## ccapehart1980 (Aug 6, 2013)

well like a 200 amnp vs a 105 stock alt should at the most kill 5 hp then 

so it would make no difference if a slapped another 105 amp alt on there or bought a high current


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## ccapehart1980 (Aug 6, 2013)

the HP loss is not relevant anyways here shortly im adding a defcent loping roller cam and roller rocker arms whole new valve setup so ill have a 15 to 20 perc HP increase with an larger intake and exhaust all thought the idleing mite be an issue i heard


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## Maylar (Dec 6, 2012)

minbari said:


> nope, just wire them in parallel.
> 
> just an FYI, a high output alt doesnt give you more power for free either. its takes more horsepower to turn than a stock one does. I think I read that the DC power 370 amp alt takes like 35hp to turn at full current.


Conversion of units, 1 hp = 746 watts. So 370 amps * 14V = 5180 watts = 6.9 hp at full tilt. Of course this doesn't include mechanical losses due to friction or the efficiency of the alternator and regulator.. but 35 hp is a stretch.


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## GlassWolf (May 8, 2010)

I've written several articles about caps, too. Mine say mostly what his said. caps are AC ripple filters. 

GlassWolf's Pages

look under "electrical" if you want to read more about caps. You made a good call, as everyone already mentioned, in going with the high output alternator.


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## minbari (Mar 3, 2011)

but, even a high output alternator can have the "dimming headlights" problem. even good quality ones will not have a fast enough regulator to react to huge currently demands that only last for a few 10s of miliseconds. a cap can buffer that effect. you just have to be aware that you are masking a problem, not fixing it.


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## ATOMICTECH62 (Jan 24, 2009)

I even have "dimming fluorescents"in my shop when testing 1000+ watt amps.Im running 210 amp 12 volt power supplies connected to an 850 cca battery with 10 gauge power wire supplying the 120volt AC.


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## Roadbird (Jul 8, 2013)

Just to throw in another alternative for discussion. How about a second isolated battery dedicated to the sound system. Would that be a better way to go. [It would probably not have to be as big as the regular battery.]


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## Roadbird (Jul 8, 2013)

By the way. When I say isolated, I mean electrically isolated. They sell systems like that.


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## minbari (Mar 3, 2011)

How would you charge it?

sent from my phone using digital farts


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## Roadbird (Jul 8, 2013)

Hi minbari,

Here is a good link to a video showing how it works including animations.
In my opinion forget the solenoid type, it is the diode type that I personally would use.

Having said that, I remember now why capacitors do work.

Batteries have what is called internal resistance. That means when you draw a current they will drop voltage. Not drop voltage because you are discharging the charge, but because there is an electrical resistance to the current flow in the battery itself. That internal resistance can actually be field tested by a test setup that measures the voltage drop at a controlled current draw. Then V=IR or R then equals V/I. Okay maybe getting too wonky here.

Anyway, for the purpose of this discussion, when you hit a prolonged big bass rift, you can theoretically drop the voltage immediately from the battery due to the internal resistance. That in effect would be an A/C like "ripple" on your DC power supply. And this is where the capacitor comes in. Compared to a battery, a capacitor has no internal resistance, it will not instantaneously suffer a voltage loss as a result of the amplifier draw. Yes it will eventually lose charge but if things are working as planned not enough to clip or degrade the amplifier operation. It is a buffer for this concern.

Now, lights flickering, I think the solution is the isolated audio dedicated battery. Add to the isolated audio dedicated battery a large cap and probably things are going to be good.
By the way, adding the large capacitor to the dedicated audio battery would also make it possible to use a somewhat smaller second dedicated audio battery.

Contrary to some views, a capacitor is just a battery with no internal resistance.

All of this had to be done with safety in mind. If anyone wants to do it, I would suggest researching it for several days to do a safe and effective job.


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## Roadbird (Jul 8, 2013)

Oops. Forgot the link:

Battery Isolators - Different Types & How to Install » Educational - Category » Sonic Electronix Videos


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## minbari (Mar 3, 2011)

For Audio you don't want the diode type those type drop voltage we will lose current based on that little voltage drop also the diode type: have to dissipate heat inside the diodes I would forget those types. I would look at the type that you the mosfets and an actual have a control board and don't get the diode types.

A cap has properties that a battery doesnt have. They both store energy, that is the end of thier similarities 

Esr in a good cap is just as low as a battery. Both are in mili ohms

sent from my phone using digital farts


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## 69Voltage (Jul 30, 2013)

Previous vehicle was a '97 Ram 1500, before I learned about proper audio system builds. Had a local shop(Kustom Kar Sound on Bell Rd. and I-17) install the system which included tweeters in the pillars, mid range in the doors and four 10" JL subs(yeah, I know) behind the seats. Didn't notice any problems except while driving at night. Lights would dim on every bass hit. Explained the issue to them and they recommended adding capacitors. Had them installed and it made the dimming issue disappear.

Now I'm not sure if I just "band-aided" the issue, or if it was a legitimate fix. Never had problems with my alternator or battery after the capacitor install. BTW, was using an Optima battery at the time.

If I had the same issue at this time in my life, I would definitely do more research before agreeing to their first recommendation.

Just thought I'd comment FYI.


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## GlassWolf (May 8, 2010)

Roadbird said:


> Just to throw in another alternative for discussion. How about a second isolated battery dedicated to the sound system. Would that be a better way to go. [It would probably not have to be as big as the regular battery.]


the link I supplied answered this question for you 

I run both a HO alternator and isolated battery dedicated to the audio system. They both have separate and distinct purposes. The battery stabilizes voltage, and acts as the main source of current when the engine is off. When the engine is running and above idle RPM, the forward voltage is higher from the alternator and voltage regulator than the battery's own voltage, thus the batter is (or should be) in a charge state, and the alternator is supplying the current for the audio system as well as the rest of the car. Ideally for a high current system you plan to use both while driving and while parked, you'd want both an isolated battery and a HO alternator.


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## qwertydude (Dec 22, 2008)

I've actually built separate batteries for high powered systems before. Being a former nuclear engineer, power systems, charging and power management was a specialty of mine.

Headlight dimming is not cause by a sluggish slow to react regulator. The regulator can regulate voltage nearly instantaneously, in actuality it can regulate the voltage as quickly as a the period of the ac waveform. The problem is simply the design of an alternator alternators are not an inherently efficient design, a 370 amp alternator pulling 35 hp is only 20% efficient, 370 amps at 14.4 volts is only 7.14 brake horsepower. 

The dimming is simply the alternator reaching it's limit. The field coils can only saturate to a certain extent and alternators are generally rated at their maximum current at quite a high RPM. In fact most reneweable energy hobbyists know this fact. A normal 120 amp alternator at full field saturation, as in more field current will not increase output, will only output half it's rated current at 2000 RPM. You'd have to run them at 4000 RPM or more to get the full rated current. Any lower RPM and you'll get dimming at just half the rated current. This is also why high output rewound alternators need overdrive pulleys in order to make their power they simply need more RPM. Car alternators weren't designed to output their rated current at idle because if they did, they'd explode by the time you get them to redline.

If it was simply a sluggish regulator then you can run an experiment, try running your car and connecting an automotive load tester, you'll find that the lights dim and stay dim so long as the load tester is run. If it was simply a matter of slow responding regulators it would dim and then get back to full brightness. And then try running the load tester while revving the engine, it will dim less.


Now that the electrical principles of alternators have been explained here's how I built my systems before to deal with limited current output. If you look at the dynamic vs average power, average power for music only tends to be about 10% of the peak. So if the fuse rating for the amp is 100 amps, you can theoretically get away with a system that can supply and buffer 10 amps of continuous current and the amp would never know the difference.

So this can greatly ease the burden on an electrical system. Instead of having to supply 100 amp peaks and their associated voltage drops which are the cause of headlight dimming all you need is a good battery like an AGM capable of feeding the amps' maximum current without dropping voltage down dangerously low, most decent AGM's can do this easily. Then simply connect it in parallel with the car battery and it's usually a good idea to install a battery isolating relay to prevent discharge when the car is off. Then limit the charge current with a PTC circuit in series. Don't know how to build one? Well this is easy use a 12v automotive light bulbs, its easy to use the 12v 100w halogen units to get large current capability in a small package. Connect enough in parallel so that when you test the amplifier at maximum power with a test tone you get about 10% of the amps maximum current draw to charge the battery, if you wanna be safer 20%. Enclose the bulbs in a fireproof metal box. Now you have a system that limits the charge rate to the rear battery so your light will never dim. Now unfortunately your amp won't be making the full power it's rated for of unless it's a regulated amp, but your headlights won't dim, so you have to take your pick. Using this system I'm easily capable of running just a 12 gauge power wire to the back of my SUV too, the battery to the amp of course get 4 gauge.

When the amplifier draws more than the 10-20 amps you limit the charge rate to the amp draws from the rear battery instead of drawing from the car's electrical system. So the headlights don't dim. Now 10-20 amps is plenty for daily driving unless you seriously bump the system constantly. In which case I fear for your hearing but every time you do turn it up the design is such that it can't draw more than the limited charge rate. As long as you balance the charge rate with the average current draw the rear battery shouldn't die over time. Dimming solved.


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## ccapehart1980 (Aug 6, 2013)

okay so far i everythings hooked up and i got a brand new red top and a stock alt and i get a barely noticeable headlight dim when i driving earlier you gotta be watching for it 
but the clarion deck i got i sure noticea little there the diming when the bass hits 

now i did notice everything diming with the old ass interstate batt but when i replace with optima red top it got rid of most except like i said before in the deck i notice it there its a clarion cz 702 or somethin 
so how ever this **** works that optima battery help quite a bit i ordered 0 guage wire for the alternator aswell and then im going to do a second alt or like i said in another post amazon has a 250 alt for like 140 bucks all good reviews 
teh more expenisve high current alts actaullly dont have great reviews 

i read somewhere some guys suggested installing a cap between the alt and battery is there any method to this madness or whoever suggested that a retard


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## danno14 (Sep 1, 2009)

GlassWolf said:


> the link I supplied answered this question for you
> 
> I run both a HO alternator and isolated battery dedicated to the audio system. They both have separate and distinct purposes. The battery stabilizes voltage, and acts as the main source of current when the engine is off. When the engine is running and above idle RPM, the forward voltage is higher from the alternator and voltage regulator than the battery's own voltage, thus the batter is (or should be) in a charge state, and the alternator is supplying the current for the audio system as well as the rest of the car. Ideally for a high current system you plan to use both while driving and while parked, you'd want both an isolated battery and a HO alternator.


Well put

So what if, and I acknowledge that my particular scenario is somewhat unique:

The car is stock with paired, non- isolated group 93 batteries (h8 has become the replacement). No possible option currently exists for a larger alternator, and stock is 140a. LOTS of amplifier capability but there will be very infrequent heavy demand placed upon them, as I'm not a bass head and its a "toy car". (System not live yet). 
Pair of Macintosh mcc406's, single zapco 9.0. 

My plan, which is open to change as the circumstance determines, is for a 50f cap in lieu of a third battery. IF the need arises. 

Discuss, and shoot holes as you will


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## RNBRAD (Oct 30, 2012)

In lamens terms, I look at a cap like a room with positive air pressure. The amp is a room with negative air pressure and the battery is a room with static pressure. When the "door" is opened to the amp room, air is pulled from the cap room first. This immediate inrush comes mainly from the cap room with a trickle from the battery room. The cap room will experience a negative pressure below that of the battery room (or drop below bat voltage at fluctuating levels). When the amp door closes, this negative pressure (voltage) from the cap room further pulls air from the battery room facilitating a quicker than normal flow of electrons. 

So what does this mean? It basically means a cap creates a more efficient flow of electrons based on it's internal properites. It's like an electron pump. Matters of fact, that is exactly how it operates. Comparatively speaking to a battery, a capacitor has a greater affinity for charge and discharge. It does it magnitudes faster as a result of this. I've used batteries with the same ESR rating as my caps and it's still not the same performance. 

Ok, now if this "setup" can deliver power more efficiently, I bet it will use more power don't you think? Of course it will!!! So is a cap a good fix for a poor alternator or battery? Uh no, it will cause more of a problem, cause now your more efficient power delivery is causing more problem for your power creator (alt) and power storage (bat). Your now using more power than you once were. Now your so called bandaid is speeding up the demise of your poor power system doing the exact opposite that you bought the thing for.

It may have a cost, but the speed of electron delivery to your amplifier can contribute to improved transients and sound quality at certain frequencies. It does this by regulating voltage drop at the amplifier. Bar none, voltage drop would be greater at the amp without the cap. And you thought they were for just for dimming lights? Granted they can help. You want to prevent dimming lights? Wire a cap to the lights. :laugh: It may just work. Anyway caps (*quality caps*) do work for the right reasons.


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## qwertydude (Dec 22, 2008)

Even though the McIntosh is a very nice amplifier, it still only consumes 70 amps max each. That's 140 total. I think you're safe with your current setup so long as the wiring is up to snuff.

The cap won't do you much good anyways. All the high Farad caps I've seen never truly make their capacitance ratings plus those hybrid caps have a dirty little secret. In order to make their high capacitance they have high internal resistance, surprisingly more than a decent AGM battery. So those are actually useless too.

So if you've got a pair of group 93 AGMs you're likely to have 1700 CCA, in reality since you're not bumping it at 0°F, you have about 2400 HCA, which is a heck of a lot. So translating that into a useable voltage you've got at least 500 amps with an amplifier friendly stable voltage, a high internal resistance hybrid cap wouldn't hope to provide that much current without dropping lots of voltage.

I'd say your current rig is good enough without the cap.


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## Roadbird (Jul 8, 2013)

qwertydude Nice comment, however "Then limit the charge current with a PTC circuit in series."

What does the acronym PTC mean? Then I can research and buy or build one. Even better do you have a link to one?

rnbrad " You want to prevent dimming lights? Wire a cap to the lights." That is one of the most creative ideas I have ever heard! Hundred percent "thinking outside the box" Has anyone ever tried this? Why wouldn't it work??


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## GlassWolf (May 8, 2010)

danno14 said:


> Well put
> 
> So what if, and I acknowledge that my particular scenario is somewhat unique:
> 
> ...


using multiple batteries without isolation really just puts more strain on the alternator, requiring the alternator to recharge all of the batteries as the system drains them as well as the power the system uses for its own power. You're better off trying the audio system with a single starter/audio battery designed for high current draw, like an oil cell or deep cycle. IF you find you have current drain problems, then consider isolating a second battery for the audio system.
There are options for alternators. You can have one custom built, or have your stock one rewound and ventilated for higher output and better cooling. I had a Ford Festiva in 1988 with a 150A Lestech alternator in it. It wasn;t an easy fit, but it worked. It's just a matter of a custom mounting bracket and an alternator that physically fits in the location.

As for the 50Fd cap, don't bother. Those capacitors that are big bricks rated for over about 1.0Fd are typically carbon capacitor banks, and have an extremely high ESR, making them completely useless as filter caps. If you have to go with capacitors, stick to the ones that look like big coke cans, and are about 1Fd or less. At least those have a respectable ESR figure.


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## Maylar (Dec 6, 2012)

Roadbird said:


> Hi minbari,
> 
> Contrary to some views, a capacitor is just a battery with no internal resistance.


From someone who designed power supplies for a living, I can tell you that this is not true. In fact there is a spec for it, called ESR (Equivalent Series Resistance).


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## Hoye0017 (Mar 23, 2010)

Maylar said:


> From someone who designed power supplies for a living, I can tell you that this is not true. In fact there is a spec for it, called ESR (Equivalent Series Resistance).


Yep. And in most cases, it's too high on caps to be able to make a difference.


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## minbari (Mar 3, 2011)

Roadbird said:


> qwertydude Nice comment, however "*Then limit the charge current with a PTC circuit in series."*
> 
> What does the acronym PTC mean? Then I can research and buy or build one. Even better do you have a link to one?
> 
> rnbrad " You want to prevent dimming lights? Wire a cap to the lights." That is one of the most creative ideas I have ever heard! Hundred percent "thinking outside the box" Has anyone ever tried this? Why wouldn't it work??


PTC = positive temperature coefficient thermistor. this not what you want, and I am sure Qwerty just got them backwards. a PTC is a polyfuse. once you exceed a certain current, it will "trip" and disconnect the input. these are commonly used as "self resetting fuses"

An NTC is a device that will limit current without disconnecting the input. these are commonly used as "inrush limiters" for high current motors or amplifiers. it keeps high spikes from occuring.


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## minbari (Mar 3, 2011)

Hoye0017 said:


> Yep. And in most cases, it's too high on caps to be able to make a difference.


I think that was his point. a cap is not a battery and only the best of caps come anywhere near the ESR of a battery.


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## RNBRAD (Oct 30, 2012)

Roadbird said:


> qwertydude Nice comment, however "Then limit the charge current with a PTC circuit in series."
> 
> What does the acronym PTC mean? Then I can research and buy or build one. Even better do you have a link to one?
> 
> rnbrad " You want to prevent dimming lights? Wire a cap to the lights." That is one of the most creative ideas I have ever heard! Hundred percent "thinking outside the box" Has anyone ever tried this? Why wouldn't it work??


It would work no doubt but how well it would work is the question. I almost tested this, prolly still could. Problem though is when you switch off lights, they will then drain the cap. When you switch it back on, what will happen to the switch as the cap charges? A dead cap is like a short circuit when it charges. I large quality cap will surely create a problem. Somehow it should be wired before the switch.

On a side note, that's something I've never experienced from any battery of any type. That's why a caps properties cannot be compared to a battery even with equal ESR. No battery I've ever seen has that kind of affinity for charge & really discharge. Reason they don't put batteries in a defibrillator, a battery can hold more charge but cannot deliver the joules instantly. A defibrillators shock has to be delivered at an exact moment of the cardiac cycle. A split second off can be certain death. Anyway something to think about.


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## qwertydude (Dec 22, 2008)

minbari said:


> PTC = positive temperature coefficient thermistor. this not what you want, and I am sure Qwerty just got them backwards. a PTC is a polyfuse. once you exceed a certain current, it will "trip" and disconnect the input. these are commonly used as "self resetting fuses"
> 
> An NTC is a device that will limit current without disconnecting the input. these are commonly used as "inrush limiters" for high current motors or amplifiers. it keeps high spikes from occuring.


A positive temperature coefficient resistor simply means a positive coefficient of resistance. What's commonly called a resettable fuse is a PPTC, these are non linear thermistors which will cutoff current until the current is removed. In this case you don't want to remove the current but limit it. And a 12v light bulb is a nearly perfect PTC type device for 12v circuits.

And as for why defibrilators don't use batteries there's no reason why they couldn't but it would be very inefficient. They need to shock at 300 to 1000 volts and up to 60 amps but it's for a very short amount of time. You'd need a very big battery to accomplish that, you could probably build a lipo battery to provide that kind of power but it's better in this case to use a capacitor. Also the design is that you can charge a specific amount of charge in joules to the cap so when it discharges you know how much elecricity you get. Batteries are not "slow" I don't know how this myth keeps getting perpetuated. A battery can discharge a steady voltage the instant you connect to the terminals. It's when you start draining too high a current that the voltage dips it doesn't matter whether you're draining that current "fast" or "slow" the voltage dips regardless.


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## minbari (Mar 3, 2011)

qwertydude said:


> A positive temperature coefficient resistor simply means a positive coefficient of resistance. What's commonly called a resettable fuse is a PPTC, these are non linear thermistors which will cutoff current until the current is removed. In this case you don't want to remove the current but limit it. And a 12v light bulb is a nearly perfect PTC type device for 12v circuits.


I agree, I use them to charge caps initially. but, they are not very practical for day to day use. An NTC will do what you are saying as well. more than one way to skin a cat 


> And as for why defibrilators don't use batteries there's no reason why they couldn't but it would be very inefficient. They need to shock at 300 to 1000 volts and up to 60 amps but it's for a very short amount of time. You'd need a very big battery to accomplish that, you could probably build a lipo battery to provide that kind of power but it's better in this case to use a capacitor. Also the design is that you can charge a specific amount of charge in joules to the cap so when it discharges you know how much elecricity you get. Batteries are not "slow" I don't know how this myth keeps getting perpetuated. A battery can discharge a steady voltage the instant you connect to the terminals. It's when you start draining too high a current that the voltage dips it doesn't matter whether you're draining that current "fast" or "slow" the voltage dips regardless.


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## RNBRAD (Oct 30, 2012)

With a defib, it's power density. Capacitors have a power density rating magnitudes greater than a battery. Power density is defined as the product of energy density, multiplied by the speed at which the energy is delivered to the load. The greater power density results in much shorter charge/discharge cycles than a battery is capable. So a battery *is* slow when compared to a capacitor. A battery uses a chemical reaction to make power. This chemical reaction is inherently slow as compared to the same process within a capacitor. So it's not really a myth at all when you look at it like it should be, apples versus apples. We don't have to say a battery is slow, but I can guarantee you that a battery cannot cycle x amount of power as fast as a cap of equal power density. Caps are used in very short, high burst situations for a reason. 

I would agree that a large enough battery could equal the output of a capacitor for the short burst, but I can guarantee that same battery "*will not*" recharge that amount of power like a capacitor.

I could see in a code situation charging a battery to deliver x amount of joules. Ok we can deliver the shock in approximately 5 minutes. :laugh:

Oh and let me reiterate, you cannot compare ESR of a battery and a cap of equal ESR ratings and assume equal performance. Just doesn't work that way, not even close.


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## qwertydude (Dec 22, 2008)

minbari said:


> I agree, I use them to charge caps initially. but, they are not very practical for day to day use. An NTC will do what you are saying as well. more than one way to skin a cat


If you use an NTC you can cause a runaway. An NTC has a negative coefficient of resistance when it comes to temperature so the more current, the more heat, the more current it will allow until the NTC burns up. It will limit inrush current but will allow maximum current to flow eventually. You don't want maximum current to flow ever in this particular current limiting system.


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## GlassWolf (May 8, 2010)

yeah most of the really large capacitors, like those battcaps and 50Fd caps are carbon caps,, and have a horrendous ESR. The coke-can ones up to about 1 or 2 farads have better ESR, but still only help to filter AC ripple from the voltage regulator.

A battery produces a chemical reaction to generate power on it's own.
A capacitor, on the other hand, does not generate any power. It only stores then releases it. The problem nobody ever mentions with capacitors being used to "bolster" charging systems, is that a capacitor's voltage parallel's the circuit it's in, so if your voltage rails are already sagging from a lack of current from the battery(ise) or alternator, the capacitor will do nothing to fix that problem.

There is a reason you never see demo vehicles from capacitor manufacturers the way you do from amplifier and speaker companies. They can't prove a cap does anything to improve the system. The cap may alleviate lights dimming, but all it is doing in actuality is masking the problem of the sagging voltage rails by smoothing out the drops in rail voltage so it's more of a shallow rolling wave instead of a sharp, sudden spike. The end result is that your lights don't pulsate anymore.. they're just constantly dimmer.


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## Roadbird (Jul 8, 2013)

Hi guys!

I stand by my statement that *COMPARED* to a battery a capacitor has very little internal resistance. I have an open mind. If someone posts a reliable chart or other comparison between the two or scientific source I will stand corrected.

But here is an idea. Just to keep us thinking.

Could you run your audio gear with a diode type isolator and ONLY huge capacitor on the audio side?!

I truly don't know. It is just an untested idea that I am hopeful can be tested here.


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## jpeezy (Feb 5, 2012)

if your trying to stop dimming lights,ive had a (unfortunately)lot of experience with this,the only thing that stopped it was a jacobs accuvolt.period.this was in a navigator with two altenators,and several batteries.it was a vehicle that we built for glen robinson (retired).we literally tried everything! caps on system,caps on headlight circuit,isolated batteries(and just so everyone is aware the old style isolators,diode based ones,drop alot of voltage on their outputs,enough that it warrants not using them.Jacobs accuvolt cured problem!the one thing a can tell you from many years experience,your connections are almost more important than the equipment.use biggest wire possible,copper connectors,(if you can solder the lug ends),nuts and bolts on everything (DO NOT USE 3 SELFTAPPERS TO CONNECT YOUR GROUNDS!,)nuts and bolts.ive seen an improvment of up to a full volt back at the back of the vehicle just by improving the connections! good luck. you only get out of your charging system what you put in.if your using the factory altenator ,that is all youll get out.


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## Jepalan (Jun 27, 2013)

A super capacitor is not a battery. A capacitor is not a battery. A super cap would have to be 10 times the physical size of your car battery to store the same amount of *energy*.

Here is the biggest challenge you face in any "thought experiments" about isolating circuits and running it solely off the capacitor. Study it carefully...


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## RNBRAD (Oct 30, 2012)

It allows a battery to function more consistently or efficiently. It pulls power on the back side (load off), pushes power on the front side (load on). Does this in fractions of a second and can do it 100's if not thousands a times a minute. Downside is, little if any storage capability. I typical automotive battery could probably charge several hundred super caps.


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## qwertydude (Dec 22, 2008)

Jepalan said:


> A super capacitor is not a battery. A capacitor is not a battery. A super cap would have to be 10 times the physical size of your car battery to store the same amount of *energy*.
> 
> Here is the biggest challenge you face in any "thought experiments" about isolating circuits and running it solely off the capacitor. Study it carefully...


That chart too is entirely theoretical theory. When you start pulling serious current out of any battery there comes a point where the voltage will still sag. The chart doesn't take into account internal resistance vs ESR in high current situations. At that point a 2600 farad ultra capacitor will still maintain a solid voltage for pretty much a good solid bass note in music. Don't play continuous test tones and you'll be fine.

If you take a look the battery companies determine the CCA and HCA of lead acid batteries when the voltage sags down to 7 volts or so.

To sag the voltage that low on a decent Ultracapacitor like the 2600F you'd be pulling in the multiple thousands of amps.

That and the 2600F means literally like tying together 2600 1F capacitors. That's definitely enough capacitance to maintain a solid voltage for any music and if you're pulling less than say 1440 amps. 2600F on 1440 amps will drop only .8 volts after 1.5 seconds. That's incredibly stable. Even a good AGM would be dropping more voltage due to simply to internal resistance. So if you're only pulling 300 amps you're talking barely .8 volts in 23 seconds of continuous drain. Music peaks maybe 10% of the time so you'd have to be pulling 3000 amps of music to really get to drain the caps faster than they charge if you can sustain 30 amps of consistent current you won't drain the caps with 300 amps of fusing to you amplifiers and will definitely maintain more consistent voltage.

Show me a lead acid that can sustain 3000 amps peak while dropping less than a volt. I'll show the batteries on the nuclear submarine I worked on. I don't think you can get 6 of those cells in your car.

An ultra cap like the 2600 certainly can do wonders for a car limited in electrical output if you know how to use them.


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## GlassWolf (May 8, 2010)

RNBRAD said:


> It allows a battery to function more consistently or efficiently. It pulls power on the back side (load off), pushes power on the front side (load on). Does this in fractions of a second and can do it 100's if not thousands a times a minute. Downside is, little if any storage capability. I typical automotive battery could probably charge several hundred super caps.


Not quite. Here's the problem: The capacitor has to recharge, which takes considerably longer than it requires to fully discharge, and the charge time is a lot longer even than the typical 120 beat per minute tracks used for most pop music. If the audio system is taxing the charging system of the car to it's limits already, and thus causing the symptoms of low RPM, car stalling, lights dimming, etc, then the capacitor is going to almost instantly be discharged, and it will never get time to recharge, thus only adding further drain on the charging system. Also, as I noted earlier, the voltage of a capacitor mirrors the circuit voltage, so if your voltage rails are sagging, so is the cap's own voltage. All a capacitor does is smooth out the spikes in demand so voltage graph would look more like a wave instead of a hound's tooth, and the end result is instead of lights dimming from sudden spikes in demand over-taxing the charging system, you jsut have lights that are more consistently dimmer as a result of a charging system that is more consistently tapped out. Also, your monster capacitors rated for 50 farads and such are mostly all carbon capacitors with horrendous ESR values, making them entirely useless for the designated purpose of acting as a filter capacitor.


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## Roadbird (Jul 8, 2013)

Jepalan,
Thanks for your comment and the graph.
However, it compares apples to oranges. The cap does not have to store the same amount of energy as the battery. The battery has to store so much energy mostly for starting the engine. You are right, it would probably take the mother of all capacitors maybe ten times the size of a batter to start your car.

What the capacitor can do is provide a very fast instantaneous surge of power to keep that amp going when it demands a huge current. The battery will not do that, again, because of its internal resistance.

Two things going on here. Constant power. Instantaneous power.

By the way any takers on whether or not you could run the entire audio system off a diode isolator and huge capacitor only?


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## minbari (Mar 3, 2011)

qwertydude said:


> That chart too is entirely theoretical theory. When you start pulling serious current out of any battery there comes a point where the voltage will still sag. The chart doesn't take into account internal resistance vs ESR in high current situations. At that point a 2600 farad ultra capacitor will still maintain a solid voltage for pretty much a good solid bass note in music. Don't play continuous test tones and you'll be fine.
> 
> If you take a look the battery companies determine the CCA and HCA of lead acid batteries when the voltage sags down to 7 volts or so.
> 
> ...


Is that an electrolytic or carbon cap? If its carbon, its worthless. Esr is too high to matter 

sent from my phone using digital farts


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## minbari (Mar 3, 2011)

Roadbird said:


> By the way any takers on whether or not you could run the entire audio system off a diode isolator and huge capacitor only?


Why do you keep going on about this? No one ever said wont work. But a diode isolator is going to drop 1.2v across the diodes. Soo with car off that is about 11volts. Barely enough to run your amplifiers. 

sent from my phone using digital farts


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## Jepalan (Jun 27, 2013)

No argument from me on any of the posts following mine. I was mainly responding to this sentence in the prior post...

"Could you run your audio gear with a diode type isolator and ONLY huge capacitor on the audio side?!"

Sorry for not quoting it for clarity.

The trouble with the discussion here is that we are talking over each other. Heck we've gone from talking about ways to prevent lights from dimming to burping 300 amps into a sub.

I've been an electronic circuit designer for 25 years. It is how I make a living. I do understand how caps work and their place in a circuit. Yes, caps have their place, even in car audio, but I would posit that in *most* installations (average install for daily listening, nothing fancy), they are useless - complete waste of money.

It is completely true that a cap can supply *much* higher *instantaneous* current (short duration pulses) than a car battery. This comes in handy and is exploited effectively when making rail guns, building electric drag racers, and very non-practical but hella-fun uses of subs


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## minbari (Mar 3, 2011)

X2^^^^^^

sent from my phone using digital farts


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## RNBRAD (Oct 30, 2012)

GlassWolf said:


> Not quite. Here's the problem: *The capacitor has to recharge, which takes considerably longer than it requires to fully discharge, *and the charge time is a lot longer even than the typical 120 beat per minute tracks used for most pop music. If the audio system is taxing the charging system of the car to it's limits already, and thus causing the symptoms of low RPM, car stalling, lights dimming, etc, then the capacitor is going to almost instantly be discharged, and it will never get time to recharge, thus only adding further drain on the charging system. Also, as I noted earlier, the voltage of a capacitor mirrors the circuit voltage, so if your voltage rails are sagging, so is the cap's own voltage. All a capacitor does is smooth out the spikes in demand so voltage graph would look more like a wave instead of a hound's tooth, and the end result is instead of lights dimming from sudden spikes in demand over-taxing the charging system, you jsut have lights that are more consistently dimmer as a result of a charging system that is more consistently tapped out. Also, your monster capacitors rated for 50 farads and such are mostly all carbon capacitors with horrendous ESR values, making them entirely useless for the designated purpose of acting as a filter capacitor.


You sure about that? If you are, please post some capacitor charge/discharge graphs with charge and discharge times.


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## GlassWolf (May 8, 2010)

I don't play with MS paint to make pretty graphs. sorry. I have however posted numerous links to articles I myself, and others have written on capacitors and why they don't help, which I have also reiterated above. If the charging system can't keep up with the drain on the system because the alternator is maxed out, a capacitor is going to do nothing for you except add more drain to the circuit as it is kept in a discharged state constantly trying to recharge. If you're not maxing out the output of the alternator, your voltage rails should remain stable. I've never seen a system that is consistently played at exactly the "barely below peak output of the charging system state. Particularly not with the dynamic nature of source material, reactive load of speakers, changing volume settings, etc.


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## squeak9798 (Apr 20, 2005)

GlassWolf said:


> I've written several articles about caps, too. Mine say mostly what his said.


Did you actually write those? Because you have a bad habit of plagiarizing other's writings with zero credit to the original author and posting them on your website, which makes them appear to be your original work.


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## qwertydude (Dec 22, 2008)

Roadbird said:


> Jepalan,
> Thanks for your comment and the graph.
> However, it compares apples to oranges. The cap does not have to store the same amount of energy as the battery. The battery has to store so much energy mostly for starting the engine. You are right, it would probably take the mother of all capacitors maybe ten times the size of a batter to start your car.
> 
> ...


You sure a capacitor has to be 10 times the size of a car battery to start your car? It has to be 10 times the size or more to store the same charge as a car battery but to start the car no.

Replace your car battery with capacitors! 12V BoostPack Update - YouTube

Car starts on caps only 5 minutes in. Those are small caps too.


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## qwertydude (Dec 22, 2008)

By the way I just pulled the trigger on the 7 cell 2600f capacitor. I plan on testing it on my amp that I know will pull 80 amps in it's current setup. On my current Ford Focus I know it will pull down to 13.5 volts and will dim lights with that kind of current.

I'll put the light bulb PTC in and show that, with music, the capacitor voltage will stay way more stable than the 13.5 volts it will currently pull down to but will only pull on average less than 10.

This ought to prove that with a large enough capacitor and a limited charge will completely average out the currents spikes without draining the capacitors faster than they charge. It's always been the key that with music if you can buffer enough capacitance you can have amplifiers with insane capability but not as insane current requirements. That's actually the theory with Rockford Fosgate experimental hybrid amplifiers.


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## GlassWolf (May 8, 2010)

squeak9798 said:


> Did you actually write those? Because you have a bad habit of plagiarizing other's writings with zero credit to the original author and posting them on your website, which makes them appear to be your original work.


I credited all the sources I could locate for articles I didn't write myself. If you know of one I mised, I'd be happy to fix that error. I wrote all but about 3 or 4 of the papers posted on that site. It would have been nice if you'd simply pointed out the error instead of jumping to conclusions and accusations. Thanks anyway.


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## squeak9798 (Apr 20, 2005)

GlassWolf said:


> I credited all the sources I could locate for articles I didn't write myself. If you know of one I mised, I'd be happy to fix that error. I wrote all but about 3 or 4 of the papers posted on that site. It would have been nice if you'd simply pointed out the error instead of jumping to conclusions and accusations. Thanks anyway.


I pointed it out several years ago on SSA and you suddenly disappeared from the forum instead of responding. Once is an accident, multiple occasions isn't.

GlassWolf's Pages
Amplifier Headroom - Technical Info & How To's - SSA Car Audio Forum

*I* wrote that article for SSA. No credit or mention made on your any of your sites.

GlassWolf's Pages
Hoffman's Iron Law - Technical Info & How To's - SSA Car Audio Forum

Neil wrote that on SSA, no credit on your site and your site actually has a,copyright @ the bottom like it was your work.

Those are just the first two I know of off hand with limited research. Your article on linear motor topologies has "Neil @ SSA" buried in the middle of the page, not in the header or footer as is common so the credit to the author is obvious. You wrote all but 3 or 4 huh? Right there is 3 and I hadn't even started looking at all of the pages, just them3 I know off hand you absolutely did not pen.


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## GlassWolf (May 8, 2010)

I "disappeared" from a lot of places several years ago. I was going through dialysis and a kidney transplant.

all 3 are fixed.  I never saw your message on SSA. Really sorry. My disappearance was pretty sudden, due to the medical stuff, but I can see where it might look like I ran off. If I'd seen it back then, I'd have fixed it a lot sooner, but I appreciate the information so I can correct it now. If you find another one, feel free to PM me and let me know via e-mail, or on here, or whatever.


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## RNBRAD (Oct 30, 2012)

GlassWolf said:


> I don't play with MS paint to make pretty graphs. sorry. I have however posted numerous links to articles I myself, and others have written on capacitors and why they don't help, which I have also reiterated above. If the charging system can't keep up with the drain on the system because the alternator is maxed out, a capacitor is going to do nothing for you except add more drain to the circuit as it is kept in a discharged state constantly trying to recharge. If you're not maxing out the output of the alternator, your voltage rails should remain stable. I've never seen a system that is consistently played at exactly the "barely below peak output of the charging system state. Particularly not with the dynamic nature of source material, reactive load of speakers, changing volume settings, etc.


When you say they don't help, not sure what you mean here? Don't help what? Just ambiguously saying a cap doesn't help is open for any interpretation or meaning. We know its not a fix for a poor charging system, I was sure we were past that talking about what a cap "actually does" which I covered in post #24. 

I'm not arguing that a cap is a fix for a charging system so can't disagree with you there, but if you want to bring up a problem with my post and say this is why


> The capacitor has to recharge, which takes considerably longer than it requires to fully discharge, and the charge time is a lot longer


 then I need to see some reference, cause my numerous references say otherwise. Just back up your stance with some proof. I'm totally open for learning and ill be first to admit when I'm wrong, but I'm not taking what your saying as gospel, just because you wrote some articles. I still don't understand why you think a cap takes considerably longer to charge than discharge. Just reference your source as to what makes your statement accurate. Make sense??? I'll read your source and compare them to mine. I'll be waiting.


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## qwertydude (Dec 22, 2008)

RNBRAD you'll never get a straight answer for charging capacitors from GlasWolf.

Anyone with a basic understanding of EE theory ought to know that when it comes to capacitors they can charge exactly as fast as they can discharge. When you work out the math a capacitor's Time Constant applies whether discharging or recharging. A battery on the other hand certainly can't charge as fast as it can discharge. Try charging a car battery at 10C and see if it doesn't blow up from gassing.


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## RNBRAD (Oct 30, 2012)

qwertydude said:


> RNBRAD you'll never get a straight answer for charging capacitors from GlasWolf.
> 
> Anyone with a basic understanding of EE theory ought to know that when it comes to capacitors they can charge exactly as fast as they can discharge. When you work out the math a capacitor's Time Constant applies whether discharging or recharging. A battery on the other hand certainly can't charge as fast as it can discharge. Try charging a car battery at 10C and see if it doesn't blow up from gassing.


Amen you are exactly right, but I wasn't going to go there yet. I put them in a corner and see where they go from there.


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## RNBRAD (Oct 30, 2012)

qwertydude said:


> By the way I just pulled the trigger on the 7 cell 2600f capacitor. I plan on testing it on my amp that I know will pull 80 amps in it's current setup. On my current Ford Focus I know it will pull down to 13.5 volts and will dim lights with that kind of current.
> 
> I'll put the light bulb PTC in and show that, with music, the capacitor voltage will stay way more stable than the 13.5 volts it will currently pull down to but will only pull on average less than 10.
> 
> This ought to prove that with a large enough capacitor and a limited charge will completely average out the currents spikes without draining the capacitors faster than they charge. It's always been the key that with music if you can buffer enough capacitance you can have amplifiers with insane capability but not as insane current requirements. That's actually the theory with Rockford Fosgate experimental hybrid amplifiers.


Keep me posted, I'm highly intrigued. Some of these new caps hold a lot of power "obviously". I just wonder what if any downside there may be. I know these things may bleed a lot of power at rest. If your car sets for too many days, you may get stranded. I have that problem with a couple farads, I can't imagine a couple thousand farads. Just be aware of it.


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## hankbot (Jan 6, 2013)

RNBRAD said:


> You sure about that? If you are, please post some capacitor charge/discharge graphs with charge and discharge times.


This graph shows charge/discharge curves for caps. You can see that it takes 1 time constant to reach 63% of the charge voltage, and 4 more time constants to reach 99%(2=86% 3=95% 4=98% 5=99%). It takes 1 time constant on the discharge curve to reach 63%. That means the cap discharges to 63% 4 times faster than it will recharge from that state. Because caps are wired in parallel they will never drop the amp input multiple volts like some suggest, it just bypasses the cap when the cap can't keep up, and is just an additional drain on the system, although one that gets exponentially smaller as it approaches full charge. One thing to consider is the resistance on the amps inputs. An amp that runs around 1ohm of resistance will mean that 1 time constant on a 1F cap is one second. A cap on a system running at a small amount of voltage sag should be able to minimize or even eliminate that sag. 


The solution seems to me to be using a cap that is big enough that you are only discharging to around 95% when using constant tones to keep the charge/discharge cycle fast enough to matter on a high current RMS rating. However I'm starting to be a believer in a 1F cap as a filter on the input, and helpful for non-cyclic peaks. 

I'm liking this thread. I need to find out if the current draw from the amp is a similar waveform to the amps output, or if the internal power supplies are able to smooth them out enough. This would be one way to think of a cap, as a stiffening cap that would never fit in your amp case.


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## hankbot (Jan 6, 2013)

I'd like to clarify a couple points, was in a rush so I could go get the kiddo ready for bed. 

1. I'm not running a cap. However I have an older 1F that tested good, so I may do some experimenting. 

2. I don't feel like a cap can help much if at all if you're dropping more than .5-1 volt if you expect your voltage fluctuations to decrease noticeably. 

3. I think a lot of people talk a lot of truth and BS about caps. Unfortunately the same people that use truth also buy into and regurgitate BS. I'm not sure a cap can ever be "bad" in a system, just of little to no help if used as a band aid. Our amps are full of small caps, no one goes in and changes them for batteries. They make the current draw more linear, aka DC. 

4. Because our systems should never drop below 12.8v, the cap should never discharge lower than 89%, so the cap should never take more than 3 time constants to charge even if it becomes "fully utilized" as far as our systems are concerned. 

5. I don't know everything, I'd love for an even more in depth description if someone has clarifications or corrections.


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## RNBRAD (Oct 30, 2012)

That's correct, the fuller a cap is the less affinity it has for charge and more affinity it has for discharge and vice versa on the empty end. Your generally only going to discharge the cap a small percentage. That's why I have always used more capacitance than always suggested. 1farad per 1000 watts is just not nearly enough cause your only using about 10% of the caps capability which is very little power anyway. I think when we have these super caps that have several 100 farads with low ESR, we will truely see and hear the difference the speed of a cap can make over a battery. I just dont think we are dealing with caps that have enough storage capability. Like I say, a battery is not slow but it can't make this discharge/ charge cycle near as fast. I do think there is some audible improvement to be had with quicker power delivery. This may be the solution.

On a side note, I do worry about power dissipation with large capacitors. This also may of been what GW was referring to instead of full charge and discharge which is equal in time.


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## GlassWolf (May 8, 2010)

Read the thread again. I've explained quite clearly and precisely why a capacitor does nothing to prevent sagging voltage rails. When I stated that it takes longer to recharge the capacitor than it does to discharge it, I was referring to the fact that the cap is fully charged prior to the system being put to use. Once the alternator is maxed out, and the voltage rails sag, the capacitor never gets a change to recharge, or if it does, it's only in small bits in brief moments where the alternator isn't maxed out. The capacitor however, will discharge fully the moment that alternator is kept at a ful current capacity. Taking my statement out of context, and your lack of reading comprehension skills aside, I still don't see any way a capacitor helps for anything but an AC ripple filter. I believe there is still a challenge posted to prove the efficacy of a capacitor that pays $5,000 or so if you can prove otherwise.


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## hankbot (Jan 6, 2013)

GlassWolf said:


> Read the thread again. I've explained quite clearly and precisely why a capacitor does nothing to prevent sagging voltage rails. When I stated that it takes longer to recharge the capacitor than it does to discharge it, I was referring to the fact that the cap is fully charged prior to the system being put to use. Once the alternator is maxed out, and the voltage rails sag, the capacitor never gets a change to recharge, or if it does, it's only in small bits in brief moments where the alternator isn't maxed out. The capacitor however, will discharge fully the moment that alternator is kept at a ful current capacity. Taking my statement out of context, and your lack of reading comprehension skills aside, I still don't see any way a capacitor helps for anything but an AC ripple filter. I believe there is still a challenge posted to prove the efficacy of a capacitor that pays $5,000 or so if you can prove otherwise.


My reading skills are quite good. I stated that if you are having massive constant draws they don't help. They would help if you are having infrequent peaks that cause small amounts of voltage drop from your alternator to level out. Try rereading what I wrote before taking offense. I even stated that you need an extremely large amount of capacitance if you wanted to notice any RMS effect, and even then only with an adequate electrical system backing it. 

Also note that not once were you mentioned in my original statements. There are a hell of a lot more uninformed people out there than you and me, and I think we're on the same side of learning about this hobby and being intelligent and informed. 

Again, even if it only acts as a filter, how "bad" can it be if it can never drops below 75-80% of charge? It's current draw to charge up from there is quite small compared to what it would be pulling trying to charge from 0 volts. It seems entirely conceivable that reducing the ripples on the input, however small that reduction is, is more valuable in music reproduction than the slight peak voltage drop you might have as a consequence of its charging/discharging cycles. Look at the crazy a$$ stuff home audio guys do to try and isolate their power supplies from noise. 

Thoughts?


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## RNBRAD (Oct 30, 2012)

I think its relatively easy to hear the difference in many systems, especially mine. According to your statement, what's the reason most all manufacturers use them if they are of no worth? You think it's for AC filtering purposes only?

My problem with your analogy is its scenario specific if even close to accurate. What about when you are not capable of maxing out your alt or batteries capabilities? You know, like just a drop in voltage at your amp? This is the most common scenario regardless if you have a bazillion amp battery and alt, you will still have voltage drop at your amp. You think a cap can prevent that from happening with quick transients? You think it can smooth out the power ripple? If so do you think it can be audible? Some things you should think about and perhaps test. 

Heres my experience with quality caps. Quick transients "definite" audible difference. Long bass notes, no diff or least that i can tell, cap is probably done and no time to charge. I have only noticed this on sub amps and it is very very apparent. I have never "not" noticed this exact phenomenon if you want to call it that on any system I've added a cap to. So to convince me that they don't work is just a waste of words to me. I've used caps for 20 yrs for a reason. Still using the original red series esoteric caps, same ones from the early 90's still work like new.


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## GlassWolf (May 8, 2010)

the OP asked a question. we all gave our opinions. I think this thread has run it's course, and not it's just becoming bickering, so I think I'm done with this thread. If one more relevant to the current line of discussion comes along, perhaps we can continue this.


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## RNBRAD (Oct 30, 2012)

hankbot said:


> * I stated that if you are having massive constant draws they don't help. They would help if you are having infrequent peaks that cause small amounts of voltage drop from your alternator to level out*.


I think this is exactly where they work. Like I said before, we will see a benefit with the long current draws as caps get significantly larger in storage. Going from a 1f, to a 2000 farad will most certainly make a difference. Problem is the 1f is so small, it just inadequate for anything but quick transient pulses of power.


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## Jepalan (Jun 27, 2013)

RNBRAD said:


> <snip>Like I said before, we will see a benefit with the long current draws as caps get significantly larger in storage. Going from a 1f, to a 2000 farad will most certainly make a difference <snip>.


No. You need to get this idea of "caps helping support constant (aka "long") loads" out of your head. If you need to produce more continuous current at a given voltage, then get a higher output alternator and/or larger battery, or set up multiple batteries to load share.

Caps will always be best at filtering *voltage* ripple/spikes or dumping huge amounts of current into very low load impedances in *very short durations*.

I find it funny that nobody has talked about experimenting with connecting very large series inductors with the +12 amp power in order to filter surge demands in high current sub systems. Capacitors are voltage "springs" inductors are current "springs". 

A capacitor attempts to resist changes to the steady state voltage across it by sourcing or sinking current. (Using an electric field)

An inductor attempts to resist changes to the current flowing through it by changing the voltage across its terminals. (Using a magnetic field)

Someone should try winding some huge inductors and wiring in series with power to the amp. Multiple inductors in parallel can be used to reduce series resistance and voltage drop. A total inductance of 100mH would be a good value to start with.

The basic thought process is this: 

1) series inductors block high frequencies - this is why series inductors are used for passive LPF filters on subwoofers.
2) size the inductor (huge) so that it "blocks" your bass frequencies and put it in series with the DC power feed to the amp
3) it will act to smooth out the current load on the batt/alt system - no more light dimming.
4) the "nature" of the inductor is to use its stored energy to vary the voltage across it to keep the current constant. Therefore it will compensate for voltage sags during peak current loads and your lights won't dim.

This theory only works *IF*...

1) You can make a large enough inductor with low enough series resistance and high enough power handling.
2) The batt/alternator system is beefy enough to support the continuous/average current load of the entire system. The inductors take care of the peaks.

Why would this work? Inductors resist changes to the steady state current passing through them. They do this because of the magnetic field created by the inductor coil. 

What are the "gotchas"? A "charged" inductor that is *suddenly* disconnected from a circuit can generate thousands of volts across its open terminals as the magnetic field collapses. Toys like shocking pens and lighters exploit this characteristic, as does the spark coil in cars. A hellacious fly-back diode may be needed as well as a way to shunt the inductor out of the circuit when re-wiring.

Here is something to read:
http://brettcave.net/howto/circuits/PowerSupply_SurgeSuppression_Inductors.pdf


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## RNBRAD (Oct 30, 2012)

Jep, hopefully you wached the link above with the guy starting his car with very small capacitors. He did this over and over. I want people to understand I am not trying to fix any alternator or battery deficiencies with a cap. I use a cap purely and solely for sound quality and sound quality only. If someone think's I'm using caps for something else, they totally misunderstand my post and by far. The entire key here is for me to provide an amplifier with the least restricted (lower resistance) power source available and plenty of it. That's it, that's all nothing else. It's the same as using larger less restrictive cables, short runs, better wire. We all know the benefit. If we can't overcome the inherent time constraints of power delivery from an alt and a battery, the amount of power we have on tap "does not matter" <--- say that to yourself 50 times. The size of the battery and alt matter not. Yet you want to tell me to get a bigger alt? You miss the point bro. I'm not sure how else to explain it.

In a sound q system, immediate power delivery is key. I remember the day switching to Optima's. I noticed a difference just because of their lower ESR. Many people notice a difference bumping wire size, better connections etc. It's the same principal as using a cap. Unadultered, immediate flow of electrons a foot away with a quicker process, than pulling juice from a battery 15ft away that uses a chemical process inherently slower. Is their an audible difference here? I'm here to tell you there damn sure is!!!! Now if I can get my hands on about 2,000 to 20,000 farads with quicker performance than a battery, I'm betting I will hear an even better improvement in SQ. That's my theory. I proved the other one. So for someone to tell me to get a bigger alt or battery, those comments have no merrit for me, cause that's not what I'm trying to achieve. I could care less about blinking lights etc.. My true concern is the large capacitors static drain. That could be a problem. Anyway that's my goal and hopefully that makes sense.

Also recently, before I added these caps I posted in the sale section (streetwires). I debated cause my power wire run was short and I have a huge battery (90lbs) in my trunk and HO alt. Didn't think I could benefit from a cap as much so I tested it audibly. major improvement in quick transient tight bass notes, then it suddenly went away, I was like WTH?. I quick wired it into my amp and set it on my sub box. The bass vibrated the cap off the box and it came unplugged from the amp. I knew this immediately so no placebo affect going on here. That's my latest experience. BTW thanks for your input!!


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## Hoye0017 (Mar 23, 2010)

I've been waiting to tear this video down as an argument for car audio use. Mostly because I stopped caring. I like what he's doing but the application in this video is nowhere near the same as what you are trying to accomplish.

Watch the first video he did with the larger caps. Did you watch the part where the voltage SLOWLY climbs back up after he starts the car? 

At that point, the caps are just a huge load, keeping the voltage down by drawing current from the alternator. 

Try that test with a good battery and see how long it takes to get the voltage up.

How does this help your voltage and current supply when the car has to struggle to charge the caps now too?

Lastly, unless you have completely unregulated power supply amps with very little internal capacitance, caps won't help audibly. And even if you do have amps like that, the rest of the system will have to be really really good for you to be able to hear it.


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## RNBRAD (Oct 30, 2012)

Hoye0017 said:


> I've been waiting to tear this video down as an argument for car audio use. Mostly because I stopped caring. I like what he's doing but the application in this video is nowhere near the same as what you are trying to accomplish.
> 
> Watch the first video he did with the larger caps. Did you watch the part where the voltage SLOWLY climbs back up after he starts the car?
> 
> ...


I just point out those caps capabilities and imagine where it could take us car audio wise. Technology of caps are improving so the future of their application may improve and change. Such the same as batteries have.

If in a stereo a cap or capacitors become a huge load drawing current on the alt, this is when you need a bigger alt and more batteries. The caps are not posing the problem here. If we are worried because we dont have enough power to recharge our caps, we have other problems don't we? Take the caps out of there, the problem is still there. Lets make sure we don't have a charging issue or a battery storage problem before we add a cap. A cap needs sufficient continual power to operate. It will allow your amp to operate more efficiently and I bet your amp will consume more power. So when you use a cap, better make sure your charging system is pretty healthy. Again I reiterate, I'm not using caps for any sort of charging system deficiencies and only for the complete and unadulterated delivery of power to the amplifiers at any cost!!!!!!!!!!!!! In other words, I want the power terminal of my amplifier to have the most constant, continuous supply of steady voltage possible. Make sense?? An analogy would be having a fire hydrant in my front yard and not down the street. Make sense?? So can a cap stiffen voltage drop at the amps power terminals? Yes. What does this mean? What is a cap doing to prevent voltage drop? It has to be delivering current!!!! Is this a good thing or not?? 

The questions isn't if these caps work in this way, cause they do. The question should be.. are they worth it to you or for your system? Will you notice the difference or not audibly speaking? I have noticed it without a doubt plenty of times.

Also take a look at a Halcro home amp. These things are huge becaue of the number and size of caps they use for the power supply. These are arguably the finest amps in the world. Wonder why they use so many? Go check them out and you will ask yourself the same. Maybe it's some audiophoolery or maybe there is something to this. I'm sure if car audio manufacturers werent under size constraints, they would surely put more caps in them than they do. More audiophoolery from car audio?? or again is there something to this. If there is no audible difference, then why the hell bother!!!


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## hankbot (Jan 6, 2013)

So if inductors resist a change in current, what exactly do you think happens when the amp goes from no current to a heavy load, like the start of a loud song? It would resist the current draw initially. Sounds like a bad quality in a power supply, especially if it has the ability to generate large amounts of voltage as a byproduct of how they work. Seems like asking for a dead amp. 

If im not thinking about this correctly I'd love more details of how this is expected to help. 



Jepalan said:


> No. You need to get this idea of "caps helping support constant (aka "long") loads" out of your head. If you need to produce more continuous current at a given voltage, then get a higher output alternator and/or larger battery, or set up multiple batteries to load share.
> 
> Caps will always be best at filtering *voltage* ripple/spikes or dumping huge amounts of current into very low load impedances in *very short durations*.
> 
> ...


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## hankbot (Jan 6, 2013)

I'd also like to say that it seems easier and more predictable to use a cap to supplement the current draw to maintain your voltage than using an inductor to vary the voltage to try and regulate the current.


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## Jepalan (Jun 27, 2013)

RNBRAD said:


> Jep, hopefully you wached the link above with the guy starting his car with very small capacitors. <snip>
> 
> The entire key here is for me to provide an amplifier with the least restricted (lower resistance) power source available and plenty of it.
> 
> <snip> immediate power delivery is key.


RNBRAD - thanks for the intelligent, detailed response.

I was only responding to the sentence I quoted. "...we will see a benefit with the long current draws as caps get significantly larger in storage..."

Maybe I don't understand what you mean by "long current draws"? 

First - I agree completely that low ESR big-caps are great at dumping a BUNCH of current into a load in a very short time. Remember, I am the one that mentioned rail-guns and electric drag racers. I also completely agree that *if your amp/sub combination can pull enough peak current that your voltage would droop during those peak loads*, THEN, YES, a cap will help. Absolutely yes. The closer to the amp the cap is wired, the better - the battery, alternator and wiring have finite resistance and *if* your amp/sub pull enough peak current, the voltage at amp terminals will drop due to that resistance. A cap will dump charge and try to sustain the voltage until the peak load subsides.

My main gripe is when this concept is extrapolated to "long current draws" and that was the point I made (I think). A cap is only useful for supplying current for the short durations **when your system is loading everything heavy enough to have caused voltage to sag without the cap**. If you are doing this over "long durations" then your system is undersized. Do you see my point? Again, it really depends on what you meant by "long current draws".

Second - I never said you could not start a car with a big cap. What I said was: "a cap that could *store the same amount of energy* as a car battery would be ten times the size of a car battery.


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## RNBRAD (Oct 30, 2012)

Jepalan said:


> RNBRAD - thanks for the intelligent, detailed response.
> 
> I was only responding to the sentence I quoted. "...we will see a benefit with the long current draws as caps get significantly larger in storage..."
> 
> ...


I get your drift. I'm thinking outside the box. I want to look beyond the inherent deficiency a battery poses here. I know we can't look at a cap to supply long current needs *yet*. But that is changing and changing fast. We will have to expand our horizon, jump out of this 1 farad per 1000 watt box and try the 20k farads or 100k farads. It's coming!!!. So this makes the long current draw more practical and possible from these type of caps no? If we can pull longer current from a cap before they drop voltage and then extend the time before we pull power from the battery. If we can sustain power from a cap longer, will we see (hear) a benefit???????? That's my question. Thanks for your input!!


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## hankbot (Jan 6, 2013)

RNBRAD said:


> I get your drift. I'm thinking outside the box. I want to look beyond the inherent deficiency a battery poses here. I know we can't look at a cap to supply long current needs *yet*. But that is changing and changing fast. We will have to expand our horizon, jump out of this 1 farad per 1000 watt box and try the 20k farads or 100k farads. It's coming!!!. So this makes the long current draw more practical and possible from these type of caps no? If we can pull longer current from a cap before they drop voltage and then extend the time before we pull power from the battery. If we can sustain power from a cap longer, will we see (hear) a benefit???????? That's my question. Thanks for your input!!


I'm not convinced that caps that we would use in a car audio environment are actually getting that much better. I think your seeing huge numbers from new hybrid caps thanks to "fudge factor", and I've not seen many high farad caps that weren't battcaps. 

Again, because we shouldn't be using them as band aids, but as the last piece of an already solid system, I don't think you need 20+ farads. 1-2F should provide all the stability you need. Again, BECAUSE THE ELECTRICAL SHOULD ALREADY BE UP TO PAR.


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## qwertydude (Dec 22, 2008)

I don't think you're keeping very good track of the technology. Have you ever seen real ultracaps? I've had smaller hundred farad units before and they're the real deal and really do store as much charge as they're labeled. If you've never tested them their voltage rise from charging and drop from discharging proves they're not BatCaps which are simply thin film batteries.

And a battery including a BatCap has a more or less constant voltage while charging and discharging and can not be cycled to 0 volts without suffering damage. A capacitor can be stored shorted and in fact should be for safety reasons.


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## RNBRAD (Oct 30, 2012)

hankbot said:


> I'm not convinced that caps that we would use in a car audio environment are actually getting that much better. I think your seeing huge numbers from new hybrid caps thanks to "fudge factor", and I've not seen many high farad caps that weren't battcaps.
> 
> Again, because we shouldn't be using them as band aids, but as the last piece of an already solid system, I don't think you need 20+ farads. 1-2F should provide all the stability you need. Again, BECAUSE THE ELECTRICAL SHOULD ALREADY BE UP TO PAR.


You shouldn't be convinced, cause the car audio specific units are junk and aren't getting much better, and I would argue they are actually getting worse. The best caps are not car audio specific. I've been using Mallory computer caps for 20yrs just to get quality. If it car audio related, it's quality is highly questionable!! Car audio caps are meant to sell, look good with lots of bling, led's, chrome, voltmeters etc.. Thats basically it. I've got a hybrid and a can unit that are basically empty shells.

Btw- a Mallory 1 farad cap will cost around 300 dollars. Also many people here are basing a caps capability on an empty shell. Night and day, literally between a quality cap and some of these cheap 30 to 40 dollar 1 farad caps. They are absolutely worthless!!!!


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## hankbot (Jan 6, 2013)

qwertydude said:


> I don't think you're keeping very good track of the technology. Have you ever seen real ultracaps? I've had smaller hundred farad units before and they're the real deal and really do store as much charge as they're labeled. If you've never tested them their voltage rise from charging and drop from discharging proves they're not BatCaps which are simply thin film batteries.
> 
> And a battery including a BatCap has a more or less constant voltage while charging and discharging and can not be cycled to 0 volts without suffering damage. A capacitor can be stored shorted and in fact should be for safety reasons.


I stand corrected on the technology. 58F Maxwell ultra cap for $150. Maximum 1 second discharge 200 amps, RMS current 12-19 amps, 16v. Interesting. 9"x2"x3"

Richardson RFPD - Search-Results


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## hankbot (Jan 6, 2013)

qwertydude said:


> .... And a battery including a BatCap has a more or less constant voltage while charging and discharging and can not be cycled to 0 volts without suffering damage. A capacitor can be stored shorted and in fact should be for safety reasons.


Yeah, no joke about storing them discharged. I've heard a grown man scream like a little girl and need 30 minutes to compose himself when a small cap blew in his face. 

That safety concern was one of the reasons I never put the cap I have in the car. Nightmares of explaining to the wife why I have to buy a new car because my cap exploded and totaled the interior.


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## Roadbird (Jul 8, 2013)

I LOVE this thread. Qwerty dude. I am going to mark my calendar for a few months, then message you to see if you have done it. I admire you for planning on testing it real world.

Me. The only reason I persist in the only big cap question is because I find it intellectually
interesting. So. 

Qwertydude. Do your test. I am going to bench test an isolator/cap only system just out of curiosity. And for some who have asked, I believe I originally understood that such a system would not work with the car turned off. If not, I correct myself.

Again. This is a GREAT thread, hope Glasswolf doesn't give up on it because I think he has given us a lot to think about.


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## ErinH (Feb 14, 2007)

GlassWolf said:


> If you find another one, feel free to PM me and let me know via e-mail, or on here, or whatever.


Wolf, here's a couple more that I've noticed didn't give credit to the author or at least reference the portions pulled from said author since checking out some of your links to your site in the past.

Rear Fill
Yours: GlassWolf's Pages
Jeff's post here: http://www.diymobileaudio.com/forum/101625-post21.html

There are bits and pieces that are direct copy/paste.

SQ Setup and Theory
Yours: GlassWolf's Pages
Steve Head's (Audionutz) site: SQ system Set-Ups and the Theories Behind Them | Tutorials | Team Audionutz

Cabin Gain
Yours: GlassWolf's Pages
Article I found on Google: Car Audio Cabin Gain Transfer Function


Back on topic now.


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## minbari (Mar 3, 2011)

hankbot said:


> Yeah, no joke about storing them discharged. I've heard a grown man scream like a little girl and need 30 minutes to compose himself when a small cap blew in his face.
> 
> That safety concern was one of the reasons I never put the cap I have in the car. Nightmares of explaining to the wife why I have to buy a new car because my cap exploded and totaled the interior.


when I was in school, we used to take little pico caps and charge em to about 24volts or so and then toss to other people. great laughs, lol.


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## Darth SQ (Sep 17, 2010)

minbari said:


> when I was in school, we used to take little pico caps and charge em to about 24volts or so and then toss to other people. great laughs, lol.


We did the same in auto shop using the pre 1975 ignition points condensers. 


Bret
PPI-ART COLLECTOR


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## RNBRAD (Oct 30, 2012)

hankbot said:


> I stand corrected on the technology. 58F Maxwell ultra cap for $150. Maximum 1 second discharge 200 amps, RMS current 12-19 amps, 16v. Interesting. 9"x2"x3"
> 
> Richardson RFPD - Search-Results


This is exactly what I'm referring to when I say long or longer current draws from a cap. I'm betting we could isolate caps just for the audio and run the system entirely off capacitors. This is closer to possible. It may not be feasible but fun to think about. I would like to hear an amp that has electrons shot at it from a cannon versus a plastic spoon. I think we could see some audible performance gains with this.


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## hankbot (Jan 6, 2013)

RNBRAD said:


> This is exactly what I'm referring to when I say long or longer current draws from a cap. I'm betting we could isolate caps just for the audio and run the system entirely off capacitors. This is closer to possible. It may not be feasible but fun to think about. I would like to hear an amp that has electrons shot at it from a cannon versus a plastic spoon. I think we could see some audible performance gains with this.


For $1300 you can get two of the 500F units for 200-320 amps RMS. Of course then your talking about 17"x6"x7" worth of caps. That plus the price plus the unknown benefit makes this sketchy to me. Can you imagine if the blew up. OMG.


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## RNBRAD (Oct 30, 2012)

Pretty small for their capacity. I think 500 of my 1 farad I use now would fill up my entire car. Hmmm, are caps anymore prone to explode than say a battery? Is there a correlation between capacitance and instability? Or the larger the capacity the more dangerous they can be if they explode? These things are pure energy and not stored as a chemical, so that alone may make them more prone to volatility say versus a battery. I'm not sure, but caps are way more prevalent then batteries, and I have never seen either explode. Of course I'm not dealing with 500F caps either.


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## qwertydude (Dec 22, 2008)

Caps only present an explosion hazard if they're shorted or overcharged. Both the same hazards really as a battery since batteries can gas out or short and a gassing battery in an enclosed area is certainly the more dangerous explosion hazard than a capacitor. So as long as you take basic precautions especially not to short them you'll be as safe as running a second battery anyways.

There's no correlation between capacitance and instability. But there most definitely is one between cheapness and instability. Cheaper caps that can't hold a decent tolerance tend to be the ones that lose their capacitance but that in itself isn't a reason for explosion, usually they just leak and their internal resistance goes way up to the point where they open. So in that sense they're actually quite safe.

I can tell you one thing. I've seen caps explode and I've seen car batteries explode. But as far as accidental explosions I've yet to see a properly installed capacitor explode and I have seen properly installed batteries explode. It's almost always because the battery was discharged completely and then recharged. The cells will unbalance in a car battery when it's overdischarged. When it's recharged the high cells will gas out and can cause an explosion hazard. A single cap can discharge to zero and recharge perfectly safe.

My experimental 7S capacitor bank will therefore be slightly more prone to balance issues than a single cap but it comes with a balancing circuit just to combat balancing issues.


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## RNBRAD (Oct 30, 2012)

qwertydude said:


> Caps only present an explosion hazard if they're shorted or overcharged. Both the same hazards really as a battery since batteries can gas out or short and a gassing battery in an enclosed area is certainly the more dangerous explosion hazard than a capacitor. So as long as you take basic precautions especially not to short them you'll be as safe as running a second battery anyways.
> 
> There's no correlation between capacitance and instability. But there most definitely is one between cheapness and instability. Cheaper caps that can't hold a decent tolerance tend to be the ones that lose their capacitance but that in itself isn't a reason for explosion, usually they just leak and their internal resistance goes way up to the point where they open. So in that sense they're actually quite safe.
> 
> ...


Keep me up to speed on your cap bank. I may do the same thing next. I'm betting with enough capacitance such as you have purchased, you may experience a number of benefits. Looking forward to the report. Also see if you can do a measurement on the static drain of those caps. I think mine were around 20milliamps which is fine for several days but with my testing and research, drain increases linearly with capacitance. That won't be a good thing without a continuous source of charge. Could surely leave you stranded if not careful. Thanks for the input!!


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## ATOMICTECH62 (Jan 24, 2009)

A friend of mine put a big battery charger(we later tested it at 22vdc)on his car.Was talking on his phone,forgot about it,looked outside,seen his car smoking from every seam.
His RF 1 farad cap was spewing toxic smoke out the top.It burnt through the digital display board and clear plastic cover on top like a volcano and got so hot it melted the plastic covering on the aluminum can into bubbles and onto his trunk carpet where it was mounted.It was a sticky toxic mess.But it didn't explode.I guess the vent on the top did its job.


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## Hdale85 (Jan 21, 2012)

minbari said:


> some of what he says makes sence. the problem is its not a valve. it doesnt discharge, then recharge in two destinct steps. when the amplifier draws current, it draws from the cap and the battery and the alternator all at once. its not like it will deplete the cap then have to recharge it. he makes it sound like that it what it does, it doesnt.
> 
> that said. they do have limited uses. if you have a alternator that is not keeping up with charging the battery, then a cap will do nothing. you have to make more current, end of story. high output alt is the only solution.
> 
> ...


It could also be from a less than adequate grounding scheme or the need for a big 3 update.


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## gckless (Oct 11, 2012)

Ultracaps! Huge potential, moreso than a G31 battery. Good info in this thread:

Capacitors are cool


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## keep_hope_alive (Jan 4, 2009)

I have put Maxwell BCAP3000 banks in three vehicles and have observed excellent voltage stability. A bank of six 2.7V 3,000F caps in series is 16V rated at 500 Farads. 

In one vehicle, Enough to stabilize 4kW sine wave bursts on stock batt, stock alt, and stock alt wiring (no big 3) in a Silverado. Sustained music stays above 14V.

I am ordering two more banks of 6 for two other vehicles. 

Only danger is charging. I use a MAXI fuse holder to disconnect before disconnecting battery. Charging is through a 15ohm 75W resistor bank and takes 2-3 hours. Once charged I do jot fully discharge, just isolate via fuse.

Rich
Acoustics Engineer


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## munkittrick (Jan 7, 2008)

I think one thing that almost everyone here is failing to mention is that a capacitor is a limited-life utility. No matter how large, how powerful or how well made, the capacitor loses a very slight ability to recharge with each depletion, much in the way a car battery does over time/use. A 3-4 Farad capacitor has an absolute high-end lifespan of about 2, maybe three years with daily use. For every point between the first charge and the last discharge it loses a slight capacity and therefore capacitance. This is not to say that a capacitor is of no use, but it's NOT going to be invincible and it's not going to continue to perform at its peak over the service life of the capacitor.

That said, they are very useful in normal listening, and when used in conjunction with other power supply supporting equipment, properly installed...they DO make an audible difference. Even then, it's a matter of taste.


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## keep_hope_alive (Jan 4, 2009)

Batteries have much shorter life and are affected adversely by cold and hot temperatures. 

Rich
Acoustics Engineer


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## Smudgeface (May 15, 2012)

To address the original post, and the link references therein, here's a little tidbit of FUD that prevents me from taking the article seriously:



> Remember: the accessories (i.e. headlights) and the current output by the alternator are BEHIND the “voltage wall” of the capacitor. The current generated by the alternator is directly available and pulled by the car’s accessories due to the path of least resistance and the buffering action of the capacitor. And this happens because the capacitor’s voltage DROPS when drained by the amplifiers. Since the voltage potential is higher at the alternator end, which is BEHIND the capacitor, the accessories have a more stable voltage and current supply than the amplifiers do as the capacitor is slowly charging. The amplifiers are directly connected to the capacitor so they will also see a corresponding drop in voltage on their terminals, whereas the headlights won’t (because they are connected to the alternator & battery). Therefore, less available current is supplied to the amplifiers than is demanded; again, because there is a limited amount current available in this automotive system. The voltage on the amplifiers will fluctuate with every discharge and charge of the capacitor. But the accessories behind the capacitor won’t see such a drastic fluctuation in voltage or current; thus reducing the flickering of headlights. The capacitor is actually reducing the spikes of current demanded by the subwoofer amplifiers each time the subs hit hard. Hence, your audio fidelity is somewhat compromised.


It's statements like this that make it clear the author doesn't really know what's going on here. There is no "voltage wall", or any BS like that - I'm not sure where this guy gets this crap from, but it really bothers me when so called experts come out spouting baseless theories as fact.


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## Darth SQ (Sep 17, 2010)

Smudgeface said:


> To address the original post, and the link references therein, here's a little tidbit of FUD that prevents me from taking the article seriously:
> It's statements like this that make it clear the author doesn't really know what's going on here. There is no "voltage wall", or any BS like that - *I'm not sure where this guy gets this crap from, but it really bothers me when so called experts come out spouting baseless theories as fact*.


How about just stating your disagreement instead.
And since you've decided to opine, detail out your opinion on the matter.
Otherwise, all the above from you was just another personal attack.
Looking forward to your help in clarifying the facts of this debate.


Bret
PPI-ART COLLECTOR


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## keep_hope_alive (Jan 4, 2009)

munkittrick said:


> I think one thing that almost everyone here is failing to mention is that a capacitor is a limited-life utility. No matter how large, how powerful or how well made, the capacitor loses a very slight ability to recharge with each depletion, much in the way a car battery does over time/use. A 3-4 Farad capacitor has an absolute high-end lifespan of about 2, maybe three years with daily use. For every point between the first charge and the last discharge it loses a slight capacity and therefore capacitance. This is not to say that a capacitor is of no use, but it's NOT going to be invincible and it's not going to continue to perform at its peak over the service life of the capacitor.
> 
> That said, they are very useful in normal listening, and when used in conjunction with other power supply supporting equipment, properly installed...they DO make an audible difference. Even then, it's a matter of taste.


I'm not sure you understand how a capacitor works. Caps last for decades just fine. Just look at electronics from the 1960's that still function. Capacity is based on surface area and plate separation, two things that do not change. They typically fail from over voltage and excessive heat (beyond ratings). 

The only thing that makes ultra caps special is the use of carbon plates that have 3000-5000 times more surface area than metal plates. Since capacitance value is partially determined by surface area... ultra caps are hugely successful. 

And ultracaps are old news to us EE's. Just new to car audio since price has dropped over time.

Rich
Acoustics Engineer


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## munkittrick (Jan 7, 2008)

keep_hope_alive said:


> Batteries have much shorter life and are affected adversely by cold and hot temperatures.
> 
> Rich
> Acoustics Engineer


 I absolutely agree, but a battery's ability to discharge and recharge at the rate and volume of a capacitor is far less, and the internal degradation common to an electrolytic capacitor is an immediate occurrence that amplifies over time whereas a properly charged and maintained battery can have an identical service life with no detriment to it's ability to perform the required function of a battery BEYOND that of the audio system.

The best means of offsetting the short-lived benefits of a capacitor is to use dual (or even quad 3.3v) 6v, high-capacitance, gel-filled, deep-cycle batteries in parallel. That way, you get the LONGER drain cycle of a deep-cycle battery, the quicker charge and discharge of dual (quad) sources and the incredible life-cycle and stability of a gel-cell.


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## minbari (Mar 3, 2011)

munkittrick said:


> I absolutely agree, but a battery's ability to discharge and recharge at the rate and volume of a capacitor is far less, and the internal degradation common to an electrolytic capacitor is an immediate occurrence that amplifies over time whereas a properly charged and maintained battery can have an identical service life with no detriment to it's ability to perform the required function of a battery BEYOND that of the audio system.
> 
> .



You have some proof to back that up? Cause car batteries will last 5-7 years mac, even in a car without extra demand like a stereo system. Caps can last 20+ years . 

What exactly "degrades" in a cap? Its metal and air in most cases or diaelectric gel for electrolytics.

sent from my phone using digital farts


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## Shoutoner (Sep 2, 2013)

The article was well written. I've heard many of the points he was making before about caps and always thought it would be better to get a
Better alt then the cap


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## munkittrick (Jan 7, 2008)

minbari said:


> You have some proof to back that up? Cause car batteries will last 5-7 years mac, even in a car without extra demand like a stereo system. Caps can last 20+ years .
> 
> What exactly "degrades" in a cap? Its metal and air in most cases or diaelectric gel for electrolytics.
> 
> sent from my phone using digital farts


I don't know who mac is, but I'm not him. Good brand car batteries can perform at full expectation for about 4 years and offer up to another 2 years at roughly 85% performance before requiring replacement. Even the very best capacitor begins degrading immediately upon the initial charge, most often done as a test in the manufacturing facility. The longest a capacitor will ever function at above 85% is roughly 1 year. Beyond that, the complex make-up of dielectric polarization gels is, in and of itself a great tool for long term use, but they are widely known to be weak over their service life in a 12v system. Couple that with the intense vibration, shock and rapid charge and discharge cycle and you get a capacitor that performs at less than its rated capacitance. This isn't a scientific breakthrough. This is generally accepted knowledge in competitive circles. You can combat the fatigue by using multiple caps in a functioning parallel circuit, but they never perform to full capacity for long and they degrade electrical continuity every time they are discharged and/or charged.

As some level of proof, I'll submit that the most common repair on ANY automotive electronic unit is directly related to failed capacitance...and those are often HIGHLY oversized for the anticipated use. Both AC and DC electronics can cause havoc on an electrolytic capacitor, but the demands of the automotive audio environment exponentially degrades even the best components. It's not uncommon for electrolytic capacitors to fail IMMEDIATELY upon the first charge.

Doubt me? Find the true specs of your capacitor via the manufacturer. Measure the cap charged and during discharge. Even the most timid use shows that the recharging of the cap takes slightly longer over a given period given that the usage of the cap is similar. That is compounded by heat, poor understanding of installation, negative ionization of the suspension fluid, compression and decompression of the "plates" and delineating core as well. Like it or not, the benefit of a single cap in a power-hungry system is not as powerful as they hype that surrounds it. It's a good idea to have one if you KNOW that you're going to be trying to knock your neighbor's parakeet of it's perch daily, but otherwise it serves little purpose in real world systems.


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## minbari (Mar 3, 2011)

It was a typo, supposed to be "max"

Your opinion is still not proof. If you were right then coupling caps would fail in minutes since they are charging and discharging 20k times a second.

I have a 20 year old amplifier that has never been repaired, caps still work in it

sent from my phone using digital farts


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## keep_hope_alive (Jan 4, 2009)

I see statements without supporting information and statistics that appear made-up.

Are you saying dielectric constants or relative permittivity changes over time? 

But what is your point? If you feel caps are worthless, get off the computer and stay away from electronics. How many caps have you replaced while servicing/repairing electronics versus how many around it have been fine? What percentage of caps (mylar, foil, tantalum, etc.) have failed in all of the electronics you have ever come in contact with. 

When something is made in the billions, some manufacturing defects are expected. I've has a higher percentage of prematurely failed batteries than caps, by a HUGE margin. 

The ultra caps I'm using are used, 5-6 years old, and out of solar power storage units. They are rated for 1,000,000 full cycles.

Rich
Acoustics Engineer


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## spyders03 (Jan 5, 2013)

I feel like this has been discussed so many times, yet people that don't believe in them will never, and people that like them will always defend them. 

With that said, there is a definite benefit to having a cap, the problem people have is knowing when to use one. I prefer to have a bigger battery than a bigger alternator, but then again, I do a lot of listening (and judging) when the vehicle is off, so even a 800amp alternator would do NOTHING for me.

When your amp is requesting power, and your battery can not discharge fast enough and your alternator has to pick of the slack, by the time it has put out the power that is being requested of it, the power that the amplifier needed is already gone, going with what Minbari said, your regulator is not acting fast enough.

So, when you have a system that requires lots of power, your alternator is not going to save you, you need a bigger battery and probably a cap as well. The shop I go to has won multiple world championships for SPL in MECA, and he has shown me his system with and without caps. He currently uses the Maxwell 2.5v 2600 Super Capacitors, and he uses 7 of them. His alternator puts out 16v, so this is what the capacitors charge to. Without the cap bank hooked up, the instant he turns on his bass, the voltage dropped from 13-13.5 for the duration of the run. With the caps hooked up, his run is louder, and the voltage dropped from 16.4 to 16.3, and tipped 16.2 by the end of a 45 second run. Can you explain the phenomenon if they clearly don't work?

The key to audio is having instantaneous power, as on average a note lasts .6 milliseconds, or .0006 seconds for everyone else. During this very short amount of time, you need power available, not on stand by, there is a difference. You can quote ohms law as much as you want, but the simple fact is that power will pull from the source where it is first available. If your battery can not put out power fast enough, and your alternator isn't putting out power (even if it is running, it will only put out what it needs to, as it won't make more current than is needed, technology is great), where is it going to get the power from? Yes the alternator will pick up the slack of what the battery can not put out, however it does not do this near fast enough. 

Plus the other fact everyone seems to forget, people say that it will wear down your alternator faster. Someone PLEASE explain this to me. If you have an amplifier playing a song, it has spikes of power that it needs to put out. So, does pulling this from an alternator where the alternator has to put out instantaneous power hundreds (or even thousands) of times a second, sending the voltage regulator into an epileptic seizure make sense? Or would it make more sense to have some sort of buffer in place, where the alternator and battery can charge said buffer at a more steady pace make sense. If you drag race your car everyday it will not last as long as the person with the same car that drives an hour to and from work everyday that is all freeway. Either way your alternator has to put out the same amount of power, it's just one is much easier on the alternator.


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## munkittrick (Jan 7, 2008)

minbari said:


> It was a typo, supposed to be "max"
> 
> Your opinion is still not proof. If you were right then coupling caps would fail in minutes since they are charging and discharging 20k times a second.
> 
> ...




No worries on the misspelling. I just wanted to make sure that didn't have me confused with someone else.

IF I were right? You must have misread my message. I said that they begin to degrade immediately, and they do. They do not do so exponentially or your assertion would be correct, but it's undeniable that the circuit fails over time.

I have an a/d/s P240 in excellent working order, but the measured S/N is higher, the overall output has diminished and there is dramatically measurable 
failure in many of he components, but the most obvious id within the capacitors. I didn't say that they cause complete failure. I pointed out that they reduce performance at a higher rate than almost every other point in the electrical supply chain.





keep_hope_alive said:


> I see statements without supporting information and statistics that appear made-up.
> 
> Are you saying dielectric constants or relative permittivity changes over time?
> 
> ...





I appreciate the you "see" my statements, but am at somewhat of a loss considering that your signature is "Acoustical Engineer". I myself am an electronic engineer who specializes in high-performance, high-impact military components for combat use...so I do understand the variables at a pretty high degree.

No, I'm saying that relative permittivity through specific use causes a diminishing return over time and does so at a higher rate. The idea that the magnetic flux and other factors does not degrade the capacity, connectivity and discharge of the capacitor is simply not a logical perception. If this were true, no one would ever need to buy replacement electronics. Quality products make a difference, but they can't defy physics. If we were working with static relative permittivity...it would be a different story.

My point is NOT that they are "useless", as it is a fact that they ARE USEFUL...but the idea that a capacitor provides power at its peak performance at any point beyond the first 15k -20k cycles is just absolutely false. They have a lower rate of electronic failure than those capacitors in a circuit with resistors and isolators, but it is still a higher rate of degradation than that of the other suggestions I made above. It really is a personal choice I suppose, and there are a HUGE number of people that swear by these monstrous caps...but real world measurability does not stray from the bounds of physics...or do they?


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## keep_hope_alive (Jan 4, 2009)

Thanks for the response. I was being a smart ass. 

The problem with measuring capacity lies in tolerance. You can't assume the number on the side is what it started out as. Also, a cycle needs to be defined. A few tenths of a volt is a cycle?

My personal experience with these ultra caps is hugely positive and my personal experience with batteries is negative and frustrating. 

Rich
Acoustics Engineer


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## munkittrick (Jan 7, 2008)

keep_hope_alive said:


> Thanks for the response. I was being a smart ass.
> 
> The problem with measuring capacity lies in tolerance. You can't assume the number on the side is what it started out as. Also, a cycle needs to be defined. A few tenths of a volt is a cycle?
> 
> ...


 It's cool. If I wasn't such a sport, I wouldn't bother trying to communicate...but you guys are pretty advanced...and I LOVE progress, even when, and/or if I'm wrong.

Tolerance IS the key, but when I typically look at tolerance I assume that the very best provided "reference" number is almost always based on a test model that is not utilized as prescribed in order to get an accurate tolerance of a given material over time. Our manufacturing ability is closing the gap at a breakneck pace, but we're still at the mercy of physics with the current production models.

As for the term "cycle", the very nature of a capacitor is either "on or "off". There are digitally controlled capacitors, but they can only regulate the flow of charge, not the degree or volume. That being the case, a "cycle" is ANY fluctuation at all. Therein lies the most detrimental piece of the pie. Heavy use elevates outside factors like heat and internal compression, but there is no electrical difference to the capacitor regardless of the usage when alleviated of these factors. That said, we cannot alleviate those effectors and the formula is invariably changed from the bench measurements and testing. Most people misunderstand the innate function of a capacitor and are easily conned into thinking that it's a vaccine instead of a bandage.

Now, all that considered, they are still not useless...but they are not going to do what they are designed to do in perpetuity making the investment a diminishing return item...like wives. They start out great...but they forget how the stove works, can't seem to keep the car on the road and off the sidewalk and opinions of our mother-in-laws private.


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## RNBRAD (Oct 30, 2012)

spyders03 said:


> The key to audio is having instantaneous power, as on average a note lasts .6 milliseconds, or .0006 seconds for everyone else. During this very short amount of time, you need power available, not on stand by, there is a difference. You can quote ohms law as much as you want, but the simple fact is that power will pull from the source where it is first available. If your battery can not put out power fast enough, and your alternator isn't putting out power (even if it is running, it will only put out what it needs to, as it won't make more current than is needed, technology is great), where is it going to get the power from? Yes the alternator will pick up the slack of what the battery can not put out, however it does not do this near fast enough.


OMG, someone else gets it!!! This is why it is and can be audible.


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## Smudgeface (May 15, 2012)

PPI-ART COLLECTOR said:


> How about just stating your disagreement instead.
> And since you've decided to opine, detail out your opinion on the matter.
> Otherwise, all the above from you was just another personal attack.
> Looking forward to your help in clarifying the facts of this debate.
> ...


Granted, there was a fair amount of emotion in my post, none of it was intended as an attack on the author as a person. However I stand by my original impression that there is mis-information in the article which is presented as fact.

I'll break down the section in question a bit further:



> Remember: the accessories (i.e. headlights) and the current output by the alternator are BEHIND the “voltage wall” of the capacitor. The current generated by the alternator is directly available and pulled by the car’s accessories due to the path of least resistance and the buffering action of the capacitor.


The implication that the capacitor somehow influences the cars electrical system in a way that benefits the accessories more than the amplifier is absurd. The amplifier has effectively become another accessory in the car, and there is no prejudicial bias that somehow permits the headlights to pull more current. If the capacitor presents a load on the electrical system (as the author hypothesizes), it would present a load on all aspects of the system. One might rebut this by claiming the installation of the capacitor in close proximity to the amplifier is the source of this bias, but that is also non-factual. A 10' run of 14ga wire has a net resistance of 0.002 ohms (source: Resistance of Wire (Wire Resistance Calculator)). Even if you moved 150A through that 14ga wire (you'd have to be nuts), the net voltage drop would be (150A) * (0.002 ohm) = 0.3V - that's hardly isolating, especially since headlights draw closer to 5-6A.



> Since the voltage potential is higher at the alternator end, which is BEHIND the capacitor, the accessories have a more stable voltage and current supply than the amplifiers do as the capacitor is slowly charging. The amplifiers are directly connected to the capacitor so they will also see a corresponding drop in voltage on their terminals, whereas the headlights won’t


Also, very wrong. The positive terminal of the capacitor, battery, and amplifier are all directly connected to each other. A dead-short has 0 voltage potential across it. (Source: ohms law, and 4 years of electrical engineering)



> Therefore, less available current is supplied to the amplifiers than is demanded; again, because there is a limited amount current available in this automotive system. The voltage on the amplifiers will fluctuate with every discharge and charge of the capacitor.


Here is a bit of truth, however the author makes a fallacy - he assumes is previous argument is true, and states the repercussions if it is. However he has not proven his argument to be true. In fact, I'm not sure he understands the basic principles of voltage, current, resistance, or capacitance - especially with comments such as this:



> But the accessories behind the capacitor won’t see such a drastic fluctuation in voltage or current; thus reducing the flickering of headlights


There is no "in front" or "behind" here, and voltage is very different from current.



> The capacitor is actually reducing the spikes of current demanded by the subwoofer amplifiers each time the subs hit hard. Hence, your audio fidelity is somewhat compromised.


Wait...wut? How is reducing the demand on the electrical system a bad thing?


I could go on - the entire article is littered with fallacies and false information just like this.


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## munkittrick (Jan 7, 2008)

RNBRAD said:


> OMG, someone else gets it!!! This is why it is and can be audible.


 For the most part, I agree with this entire statement. My differentiation is that this "instantaneous power" isn't like a natural water spring in that you WILL lessen the responsiveness, you will loose efficiency, you will hear an audible change as the capacitor degrades and you will not have the kind of damping provided by a tightly regulated current as you do from a parallel 3.3v or 6v battery array or any other piggybacked power supply.

However, the argument of speed with respect to the capacitor is dead accurate. A capacitor will provide a needed boost of current at peak requirement far faster than a single battery, but they are no faster than a battery array once at operating temperature in the automobile environment. Another point is that the highest demand for the capacitor's speed is from 1k and up. Sure, they can make bass a bit more "punchy", but they hinder damping of smaller drivers over time as well. THAT is the core problem in my mind.


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## munkittrick (Jan 7, 2008)

Smudgeface said:


> Granted, there was a fair amount of emotion in my post, none of it was intended as an attack on the author as a person. However I stand by my original impression that there is mis-information in the article which is presented as fact.
> 
> I'll break down the section in question a bit further:
> 
> ...





EXCELLENT rebuttal. These points are overlooked and some of the "fact" is built on previous fallacy...so I'd stipulate that most of your rebuttal is true.


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## RNBRAD (Oct 30, 2012)

munkittrick said:


> > For the most part, I agree with this entire statement. My differentiation is that this "instantaneous power" isn't like a natural water spring in that you WILL lessen the responsiveness, you will loose efficiency, you will hear an audible change as the capacitor degrades and you will not have the kind of damping provided by a tightly regulated current as you do from a parallel 3.3v or 6v battery array or any other piggybacked power supply.
> 
> 
> Your kind of stuck on this capacitor degredation thing. What about the oxidation of your power connections and speaker wires? This happens too as soon as you strip the wire covering.
> ...


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## Arthurk (Feb 10, 2009)

Well this discussion got really deep but here's the reality. On a 4.6 Mustang Gt with stock alt and stock battery, a single Arc 12 powered by a single Arc ks1000, if you rock it WITHOUT the cap, the lights dim and do so very badly, hook the cap up, no dimming whatsoever. There you go. Anything over 1000 watts I wouldn't use it but for this, it DOES WORK!!


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## keep_hope_alive (Jan 4, 2009)

munkittrick said:


> Now, all that considered, they are still not useless...but they are not going to do what they are designed to do in perpetuity making the investment a diminishing return item...like wives. They start out great...but they forget how the stove works, can't seem to keep the car on the road and off the sidewalk and opinions of our mother-in-laws private.


i like you. 

i've been viewing on my phone all day and unable to provide any substantial response.

as far as the discussion of cap life, it's easiest to simply refer to the datasheet and dispel any doubt in reduction of capacity over life.
http://www.maxwell.com/products/ultracapacitors/docs/datasheet_k2_series_1015370.pdf

rated decrease in life is given, as well as test current, operating temperature life, etc. granted, they appear to be rounded, "average" numbers.

the discussion on speed has a caveat though. we talk about speed, but seem to neglect the path that the energy has to travel through - specifically the toroid coils. inductors oppose changes in current. this points to the differences in amplifier build quality and component quality. it has been said before (and on this forum) that the best place to provide capacitance is at the rail voltage of the amplifier: inside the amplifier, after the power supply has boosted the voltage. that is where speed really matters. of course, op-amp slew rate also plays a huge role in the end "signature sound" of the amplifier. that doesn't mean reductions in supply voltage won't be audible, because they can and can mean a reduction in power delivered as rail voltages sag. but if the output signal amplitude is well below the sagged rail voltage - is there actually any change? i don't know that answer off the top of my head.

now, we know batteries to be lumbering beasts who's chemical reactions are quite slow by today's standards. this is one reason why hybrid cars are now using these same ultracapacitors in the regenerative charging circuits because caps can charge and discharge more quickly than batteries (even the li-ion arrays they use). 

even if the capacity of a capacitor (hehe) reduces over time, it's core function does not - it will resist changes in voltage and will work to smooth AC ripples on a DC source. these AC ripples are what we want "stiffening" capacitors for. The problem in the past is that the caps available to us were too small and could not provide enough energy to "ride through" dips. i think this backs-up the argument by some that sufficient capacitance is still useful, even if the amount changes (battery capacity reduces with time also).

i cannot say definitively if putting a ultracapacitor bank in mine and other cars has resulted in sonic improvements. i can say that observed dimming and voltage drops in the vehicle have been greatly reduced and in most cases eliminated. i am re-doing my trunk and the cap bank is disconnected. the benefits it had are now even more obvious having lived with it and seen how voltage behaves on the predictable drive to/from work. 

i would like to one day do a legitimate test where i use logging volt meters to record voltage fluctuations while playing a musical track - and compare with and without while keeping alt output, engine RPM, starting battery float voltage (i.e. charged), and amplifier output constant (and also logged). then, an objective statement could be made.


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## RNBRAD (Oct 30, 2012)

Arthurk said:


> Well this discussion got really deep but here's the reality. On a 4.6 Mustang Gt with stock alt and stock battery, a single Arc 12 powered by a single Arc ks1000, if you rock it WITHOUT the cap, the lights dim and do so very badly, hook the cap up, no dimming whatsoever. There you go. Anything over 1000 watts I wouldn't use it but for this, it DOES WORK!!


That's a rare feat these days. You must of actually bought a "good" quality cap. 

On a side note- As for measuring voltage fluctuations at the amps power input, I'm betting your typical (high end by most standards)Fluke DMM will not have the reaction speed to see how much it is truelly fluctuating and it's probably just catching an average. The damage is probably worse than we can actually see for the millisecond(s) or longer of voltage drop. Hmm, maybe they should power the DMM off a capacitor. :laugh:


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## keep_hope_alive (Jan 4, 2009)

i agree a DMM is not sufficient for logging rapid changes - i was thinking more along the lines of a National Instruments lab suite with calibrated sensors. if i had nothing to do, i could write code to monitor and log the data with limitations on the sampling rate of the sensors, but i don't have that kind of time (we use LabWindows by NI at work for acoustical programs we write).


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## RNBRAD (Oct 30, 2012)

Get you an Agilent bench model that takes 50,000 readings a second at 4 1/2 digits. That'll give you some data and leave your bank account at zero digits.


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## keep_hope_alive (Jan 4, 2009)

for those looking to learn more about ultracapacitors. best to go to the source
Maxwell Technologies - Ultracapacitors - Downloads

on the subject of "cycle", here is what Maxwell does to test:
http://www.maxwell.com/products/ultracapacitors/docs/applicationnote_maxwelltestprocedures.pdf


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## keep_hope_alive (Jan 4, 2009)

RNBRAD said:


> Get you an Agilent bench model that takes 50,000 readings a second at 4 1/2 digits. That'll give you some data and leave your bank account at zero digits.


maybe the next time i'm at UW-Platteville I can ask the EE department chair if i can borrow equipment in the engineering lab to do my tests. pretty sure he'd say yes. the real trick would be staying sober long enough to make the test legit - i like to drink when i visit UW-P. 

maybe instead i pose it as a student project.


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## RNBRAD (Oct 30, 2012)

Has Ioxus Built a Better Ultracap? : Greentech Media

“It is like a stack of playing cards in a vacuum-sealed bag instead of a round can with heavy terminals and wasted space,” Hall said. He added that cylindrical ultracaps from other vendors like Maxwell Technologies take up more volume, are heavier, and have less energy and power density


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## Darth SQ (Sep 17, 2010)

Smudgeface said:


> Granted, there was a fair amount of emotion in my post, none of it was intended as an attack on the author as a person. However I stand by my original impression that there is mis-information in the article which is presented as fact.
> 
> I'll break down the section in question a bit further:
> 
> ...


Thank you.


Bret
PPI-ART COLLECTOR


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## Roadbird (Jul 8, 2013)

I have big a** capacitors from my engineering days at UF that I have been using for over
45 years. Never exploded. Never smoked. Still working just fine. Think about it, almost a half century old and still working. How many batteries could do that?


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## hankbot (Jan 6, 2013)

The cap I have had tested is almost 15 years old and had around 940uF measured on an LCR. Not bad for an old 1F Tsunami (no name) cap. I think I paid around $30-$40 for it in 1999. 

I agree that caps generally have a long life, even if performance is slightly reduced over time.


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## minbari (Mar 3, 2011)

RNBRAD said:


> Get you an Agilent bench model that takes 50,000 readings a second at 4 1/2 digits. That'll give you some data and leave your bank account at zero digits.


You can also use a pretty simple dso. Even 20-50mhz would easily measure voltage changes like that

sent from my phone using digital farts


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## gtsdohcvvtli (Aug 17, 2011)

Replace halogen headlamps with HID's. Replace all incandescent light bulbs with LED counterparts inside and outside of the vehicle. 

No dimming lights, no need for a capacitor. Problem solved


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## Hispls (Mar 12, 2008)

I've been running multiple batteries for about 20 years now and NEVER used an isolator. Really I can't see the point.

1 battery per 1000W in amplifier power is a good rule of thumb. You can likely get away with less (much less depending on your listening habits and definition of "music"), and you may need more if you are running all A/B amps or class D at very low impedance, but this is a good starting point.

HO alternator is always a good idea, and often an external regulator is nice. My Jeep for example only regulates to 13.6 or so on the factory charging system which IMO isn't even enough to properly maintain batteries.

Zed Leviathan and JBL/Crown A6000GTI on total of 6 group 34 size batteries and HO alternator. I can play music at nearly full tilt for a good half hour at highway speeds (possibly more, but subs get a little stinky and it can get physically uncomfortable), 1 or 2 songs at idle before voltage drop becomes a concern.

Long story short, buy amps with regulated power supply and add batteries until you can keep up with your demands.


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## qwertydude (Dec 22, 2008)

gtsdohcvvtli said:


> Replace halogen headlamps with HID's. Replace all incandescent light bulbs with LED counterparts inside and outside of the vehicle.
> 
> No dimming lights, no need for a capacitor. Problem solved


Actually LED's flicker more than incans unless actively regulated or at the minimum have a large enough power capacitor wired across them. Incandescent bulbs have a thermal decay. Turn off power and the residual heat in the filament keeps it lit. LED's on the other hand as soon as voltage drops you'll readily see it. It's very evident if you have a smart alternator as these tend to fluctuate in voltage at idle and they flicker.


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## Hoye0017 (Mar 23, 2010)

gtsdohcvvtli said:


> Replace halogen headlamps with HID's. Replace all incandescent light bulbs with LED counterparts inside and outside of the vehicle.
> 
> No dimming lights, no need for a capacitor. Problem solved


And HID's dim too. Even digital ballast HID's.


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## gtsdohcvvtli (Aug 17, 2011)

qwertydude said:


> Actually LED's flicker more than incans unless actively regulated or at the minimum have a large enough power capacitor wired across them. Incandescent bulbs have a thermal decay. Turn off power and the residual heat in the filament keeps it lit. LED's on the other hand as soon as voltage drops you'll readily see it. It's very evident if you have a smart alternator as these tend to fluctuate in voltage at idle and they flicker.


Very true. But they 'flicker' instead of dimming. 



Hoye0017 said:


> And HID's dim too. Even digital ballast HID's.


Yup. Primarily the cheap kits. Most quality retrofits and OEM ballasts aren't really effected. Most of higher quality oem grade ballasts have regulated ouputs. If they were so easily subjected to dimming/pulsing, they would never get past modern DOT or ECE approvals. Especially hybrid vehicles where there is a dip in voltage when the gas engine kicks on.


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## ccapehart1980 (Aug 6, 2013)

okay i emailed my brothers physics teacher and his doctorate or phd is the area of physics that deals with this stuff and his **** says MIT so ill take his word witha bucket of salt 
or better yet 100lb bag of salt anyways what he said was a capacitor being used in that way is ineffective and depending on the size of the amp and capacitor and alternator its actaully counter productive he said its simple a cap is irrellivant more accesories requires more juice now my amp is somewere around 1200 watts rms right know as is and on my tahoe with zero guage wire upgrade and i got a an optima red top i dont really notice any flicker i think the stock alt in a tahoe is either 105amp or 130 amp


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## qwertydude (Dec 22, 2008)

ccapehart1980 said:


> okay i emailed my brothers physics teacher and his doctorate or phd is the area of physics that deals with this stuff and his **** says MIT so ill take his word witha bucket of salt
> or better yet 100lb bag of salt anyways what he said was a capacitor being used in that way is ineffective and depending on the size of the amp and capacitor and alternator its actaully counter productive he said its simple a cap is irrellivant more accesories requires more juice now my amp is somewere around 1200 watts rms right know as is and on my tahoe with zero guage wire upgrade and i got a an optima red top i dont really notice any flicker i think the stock alt in a tahoe is either 105amp or 130 amp


Often times physicists use oversimplified models in order to run their calculations. I don't think he understands how amplifiers use power. Heck most of the people on this board don't understand how amps use power. If you can clarify to him to better understand that amplifiers are not a constant drain which is what the phrase, "more accesories, more juice," implies, and if he knew what peak demands amps use, average power with music, and internal resistances and regulators in alternators and how they affect the power transfer then he'd quickly change his tune. Because using that simple logic starter caps on motors would do nothing, and amplifiers wouldn't need main board power supply caps. But that's sorta what living in the world of oversimplified models does to you.

A physics teacher is far from an electrical engineer or even a qualified technician. I don't think he has enough in depth understanding of the average power of music, things like power transfer efficiency, large capacity capacitors, etc. I bet I could make that PHD eat his words by powering my 80 amp amplifier with only a 10 amp power supply and very large ultracapacitor. Because of the way music works if you can completely average out the high peaks average power consumption of the amps is very low.

I've just finished the long term voltage test of my ultracapacitor. The good news is it will hold a steady 2.2 volts per cell times 7 cells for a very long time which means it won't slowly drain my battery. Next test once I build the rig will be to test what kind of current I need to limit the charge rate to to maintain acceptable voltage. My own calculations say I need at least 10% maximum power in order to keep voltage stable. I'm increasing this to 25% in my car but just for kicks I'll post a video soon of a limited charge rate of only 10 amps or so into the ultracapactior and it powering my 80 amp amplifier on music just fine.

If caps truly do nothing this setup won't work. But I already know the outcome because I've built a similar setup before but using AGM batteries instead of caps. Ultracaps ought to keep voltage even more stable than the AGM and I should be able to prove that even with a limited electrical system you can run high power amplifiers, of course for music only. Not continuous drains.


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## Roadbird (Jul 8, 2013)

Quertydude

Ditto the Dude!

Roadbird


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## ATOMICTECH62 (Jan 24, 2009)

X2

Physics can be specialized just like a medical doctor sending you to a Neurologist.
Just because you are a Physicist doesn't mean you are a PHD in Astrophysics,Semiconductor or subatomic particles etc..


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## Darth SQ (Sep 17, 2010)

ATOMICTECH62 said:


> X2
> 
> Physics can be specialized just like a medical doctor sending you to a Neurologist.
> Just because you are a Physicist doesn't mean you are a PHD in Astrophysics,Semiconductor or subatomic particles etc..


Bingo!


Bret
PPI-ART COLLECTOR


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## RNBRAD (Oct 30, 2012)

ccapehart1980 said:


> okay i emailed my brothers physics teacher and his doctorate or phd is the area of physics that deals with this stuff and his **** says MIT so ill take his word witha bucket of salt
> or better yet 100lb bag of salt anyways what he said was a capacitor being used in that way is ineffective and depending on the size of the amp and capacitor and alternator its actaully counter productive he said its simple a cap is irrellivant more accesories requires more juice now my amp is somewere around 1200 watts rms right know as is and on my tahoe with zero guage wire upgrade and i got a an optima red top i dont really notice any flicker i think the stock alt in a tahoe is either 105amp or 130 amp


We are not trying to cheat any laws of physics here. Just some people don't understand the goal. If our average power consumption is greater than our supply, no amount of capacitors will fix the inevitable. That's the counter intuitive aspect, which is not this scenario being discussed.

Qwerty is basically stabilizing peak demands and controlling charge current to ease the burden on his electrical system. Will this work? Absolutely no doubt that it will and if someone states otherwise, they need some simple education. 

Another aspect I'm more interested in is the sonic improvements from this type of setup. There is a sweet spot that can be achieved that will allow you to get by with less amperage availability which qwerty is achieving. But back to the basics, if consumption is greater than supply, at some point something will give. Depending on the proportionality of supply versus demand, the greater the difference the greater the strain.

What does this mean? It means a cap is not nor ever will be a fix for a short supply and its not really meant to be. But with qwerty, he is lessening the peak burdens and even if you do have more demand than supply, I feel this is not a fix, but may extend the life of the alt/battery as a prolonged benefit. It just eases the burden regardless of you charging and storage capabilities.


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## ccapehart1980 (Aug 6, 2013)

i didnt meant to be all smart allic and go get ask the physics teacher electricity is his area of expertise so i consulted the expert and when i explained how these caps are marketed and how they are installed and his first response was that of confusion and a head scratch at the end of the conversation it boiled down to is it helps the flicker affect inthe other accessories like lights but your sacrifising voltage your amplifiier is getting less voltage = less watts less volts is damaging under a certain voltage 
capacitors werent even originally designed for this purpose i think the first practical app was to send current over great distances 
i believe the first practical app


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## spyders03 (Jan 5, 2013)

Simple question.

You are running your stereo hard while the vehicle is off. Your amps demand a total of 105 amperes at one time, and your battery is capable of putting out 50 amperes at any given moment. What happens next?


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## ccapehart1980 (Aug 6, 2013)

yoru engine wont start your battery probably won have juice to turn on any lights


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## Ram4ever (Oct 21, 2009)

To me there's a lot of unnecessary detours from the subject going on here. 

The use of capacitors is an attempt to compensate locally for excess resistance/impedance in the electrical power distribution system in a vehicle.

If you're an audiophile, as most here would claim to be, you could directly compare the situation in your car's power distribution system with damping factor in amplifiers and your speaker cables. 

It only requires a very slight amount of resistance/impedance in a circuit to choke your electrical system's ability to provide large amounts of current to a distant load, irrespective of the size of your battery or alternator. 

Remember the old 6 volt electrical systems like were used in WWII-vintage Jeeps? They had to reduce the resistance/impedance of the electrical systems somehow to spin over those old starters, and they did it with huge cables. 

Then too, consider welders, especially spot welders. They're high current sources designed for extremely low impedance. Extending their 5/8" diameter copper tongs by only 12" results in a loss of 1900 otherwise deliverable amperes. There's plenty of vehicles with power cabling which is an appreciable fraction that size range...

Any current source at one end of an electrical conductor is automatically partially isolated from the load at the other end by the cable's resistance/impedance. That's how ground loops become a large issue in audio systems. Signals can become modulated by unwelcome circulating currents which are able to develop against the cable's impedance even in very low impedance circuits, no matter that the cabling might appear quite reasonable, with heavy well-terminated cable tied off to a load on one end and a low impedance current source on the other. 

If you place a large capacitor or battery *right at* an amplifier, with extremely short, heavy cables, you've reduced as much as possible the influence of the resistance and probably impedance in the power distribution circuit. Using well-crimped and soldered connections can help with this in the long run, especially in a mobile environment where humidity, ozone, and vibration will gradually have their way with our cables.

A capacitor won't contain the same amp-hours of capacity as a typical starting battery, but it doesn't weigh much, doesn't outgas hydrogen, can dump it's charge quickly, and being located right at the amplifier, it can dump it's charge without the excess I2R losses through all the power cabling and connections to the starting battery and alternator. 

In plain words, capacitors near an amp really can help. They're no panacea, but they're a sound incremental improvement.

Now, if someone would care to come up with some room-temperature superconducting cabling for in our vehicles, we could pretty well lay some of these old demons to rest, but for now, we get to make do, and capacitors contribute in their own way when used properly.

You sure won't pry mine out of my van! ;0)


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## spyders03 (Jan 5, 2013)

ccapehart1980 said:


> yoru engine wont start your battery probably won have juice to turn on any lights


That has more to do with storage capacity, not discharge capability.

Swyped while swerving


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## Jepalan (Jun 27, 2013)

Ram4ever said: _"Now, if someone would care to come up with some room-temperature superconducting cabling for in our vehicles..."_

Don't forget to use those superconductors in the alternator windings and battery internals as well. Otherwise all you get is the ability to move the ultracap under the hood. 

BTW - *extremely* well written post. Bravo sir.


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## hankbot (Jan 6, 2013)

I'm not sure you're right about the voltage drop due to the resistance of the wire. It's always there, and will always cause the voltage at the cap to be lower than it would be with only 2" of wire between the battery, cap, and amp (impossible/impractical to do, that's why people wanting maximum power transfer always oversize power wires).

You can't ignore resistance in the conductor just because there is a cap in parallel with the series circuit. 300mV of voltage drop due to resistance in your power wires is going to be a constant (if you eliminate variables like the temperature of the conductor). The cap cannot charge to a higher voltage than the supply feeding it, in this case the amplifier power wire circuit. If your 14.4 volts drops to 14.1 from the wire resistance in that circuit, the cap will never see the 14.4 volts that your alternator puts out. 




Ram4ever said:


> To me there's a lot of unnecessary detours from the subject going on here.
> 
> The use of capacitors is an attempt to compensate locally for excess resistance/impedance in the electrical power distribution system in a vehicle.
> 
> ...


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## Smudgeface (May 15, 2012)

> I'm not sure you're right about the voltage drop due to the resistance of the wire. It's always there, and will always cause the voltage at the cap to be lower than it would be with only 2" of wire between the battery, cap, and amp (impossible/impractical to do, that's why people wanting maximum power transfer always oversize power wires).
> 
> You can't ignore resistance in the conductor just because there is a cap in parallel with the series circuit. 300mV of voltage drop due to resistance in your power wires is going to be a constant (if you eliminate variables like the temperature of the conductor). The cap cannot charge to a higher voltage than the supply feeding it, in this case the amplifier power wire circuit. If your 14.4 volts drops to 14.1 from the wire resistance in that circuit, the cap will never see the 14.4 volts that your alternator puts out.



In my previous post, I ranted about "so called experts come out spouting baseless theories as fact", and here we have another example of it. A lot of people have the misconception that voltage drop due to wire resistance is constant. This is actually not the case. The voltage drop over a wire depends entirely on the amount of current flowing through it. It's counter-intuitive, but it comes from ohms law:
V = I * R

So, here's where things get interesting: if the current through the wire is low, the voltage difference across it is 0 - ie, there is no voltage drop at all. When the amp is drawing low current, the capacitor will see the full 14.4 volts and will charge to that level.


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## basicbajax (Dec 13, 2012)

This has been the best topic/thread with ideas and reasoning that I have came across in a long time. After doing the big 3 to my F250 with dual batteries I now have a voltage drop, small, but it's there. I need to go re-check/solder all my connections. Thanks


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## hankbot (Jan 6, 2013)

Smudgeface said:


> In my previous post, I ranted about "so called experts come out spouting baseless theories as fact", and here we have another example of it. A lot of people have the misconception that voltage drop due to wire resistance is constant. This is actually not the case. The voltage drop over a wire depends entirely on the amount of current flowing through it. It's counter-intuitive, but it comes from ohms law:
> V = I * R
> 
> So, here's where things get interesting: if the current through the wire is low, the voltage difference across it is 0 - ie, there is no voltage drop at all. When the amp is drawing low current, the capacitor will see the full 14.4 volts and will charge to that level.


I meant to reply to this a while ago but forgot until basicbajax's post. Smudgeface is correct. If I had thought about it for a split second longer I would have remembered that you use a resistor to do the initial charge on the cap. The resistor causes a longer charge time by limiting the current which reduces the chance of damage to the plates in the cap. The cap does get to full voltage even with the 1k or whatever resistor you use in series with the cap. My mistake was forgetting that you may not always be pulling much current to your amp, and the cap can fully charge (potentially) during the lulls. 

*palm smacks face*

I'm sorry if I ever came off sounding like I think I'm an expert, I try not to come off that way. That's why I had the soft sell in the beginning of my post saying "I'm not sure". Thank you for the correction, it will help people form better opinions.


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## luisc202 (Oct 29, 2013)

gtsdohcvvtli said:


> Replace halogen headlamps with HID's. Replace all incandescent light bulbs with LED counterparts inside and outside of the vehicle.
> 
> No dimming lights, no need for a capacitor. Problem solved


I replaced all my interior lights in my Tundra for LED and it seems they drain the battery faster if I leave a door open for an extended period of time. hmmm weird.


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## Hispls (Mar 12, 2008)

luisc202 said:


> I replaced all my interior lights in my Tundra for LED and it seems they drain the battery faster if I leave a door open for an extended period of time. hmmm weird.


If just your dome lights drain down your battery you have no business running aftermarket audio. LED's are far more efficient than standard bulbs, simply touching either with your fingers can tell you which is efficient *hint, the one that leaves a blister is using much more current*.


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## luisc202 (Oct 29, 2013)

Hispls said:


> If just your dome lights drain down your battery you have no business running aftermarket audio. LED's are far more efficient than standard bulbs, simply touching either with your fingers can tell you which is efficient *hint, the one that leaves a blister is using much more current*.


I found the culprit and it was not the LED's. It was the Viper alarm that I had professionally installed that was causing my battery drains.


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## MetricMuscle (Sep 16, 2013)

I didn't read the whole thread and luckily a few folks with basic electrical theory have already chimed in. The article linked in the first post has some good and some erroneous information. 

The funniest part of this whole discussion is how caps don't help on the power supply side of an amplifier. Somebody better tell the amplifier manufacturers this cuz all amplifiers have capacitors built in on the power supply input side for this very reason. A good amp will have enough capacitance built into it to keep the power as stable as it needs to be for the amp to do it's job. The quality of an amplifier can usually be judged somewhat by how badly it dims the system.

If your headlights or dome light dim when the bass hits, the voltage of the entire electrical system just dipped and the lights on the amp probably dimmed too not to mention the output to the driver dipped. A cap close to the amp will provide the sudden demand for power and keep the voltage of the entire electrical system from dropping as much, thusly less or no dimming.

A capacitor wired in parallel in a DC circuit acts like a battery that can discharge more quickly than a battery can. There is no "voltage wall", a cap will provide this quick discharge of power to the entire electrical system if needed. The article makes it sound like the cap is wired in series on the +12VDC power cable going to the amps + lug. The picture he has shows it wired in parallel.

A battery located very close to the amplifier, like an external cap would be, can help but it still cannot discharge as fast as the cap and the power would not be as stable. 

You are only gonna need a higher output alternator if the voltage of your electrical system goes down and keeps going down when the car is running and the stereo is on and at max volume. 

Think of voltage as pressure.
Amperage as flow.
Power is the two multiplied together. 

The battery is a bucket of Power.
The alternator is a hose filling it up and providing power to whatever load is drawing it.
If the load draw is greater than what the hose can supply then the bucket will not be getting filled back up as all the power is being drawn to the load. 

An extra battery is just an extra bucket that will delay the power drop. A 1,000 watt system only draws big power for the large drivers producing the low frequencies. It draws nowhere near 1,000 watts continuous.


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## RNBRAD (Oct 30, 2012)

Simple explanations are sometimes the best and that is exactly right. Even high and many low end home audio system use several farads of capacitance. In car audio these amps don't have the space like home units do so most of them have less than required for optimum performance. Some home amps like Halcro are the size of a large computer tower and the sole reason is because they are loaded with caps. So do they work? Of course they do but they are quality caps, not these empty cans most people are buying today on eBay!!


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## oldschoolbeats (Nov 29, 2013)

For all the non believers caps do work, I've personally seen a bank of caps installed and increased the SPL 6.3db.... but that bank of caps was in the neighborhood of 600 farad and was backed by 4 alts and 24 batteries.... caps do have they're place but if your pulling 200 amps and your alt is only a 70 amp stocker and have a crappy battery under the hood don't expect it to help your situation out any whatsoever...


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## oldschoolbeats (Nov 29, 2013)

MetricMuscle said:


> I didn't read the whole thread and luckily a few folks with basic electrical theory have already chimed in. The article linked in the first post has some good and some erroneous information.
> 
> The funniest part of this whole discussion is how caps don't help on the power supply side of an amplifier. Somebody better tell the amplifier manufacturers this cuz all amplifiers have capacitors built in on the power supply input side for this very reason. A good amp will have enough capacitance built into it to keep the power as stable as it needs to be for the amp to do it's job. The quality of an amplifier can usually be judged somewhat by how badly it dims the system.
> 
> ...


Very well said, kind of hard to put it in layman's terms for all to understand but that right there is 100% correct.

That bad taste that a lot of people have In there mouths about caps is that they go down to they're stereo shop and buy some amps with a bazillion watts and they sell them a 1 farad cap for $200 and it does nothing.....


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## moparman1 (Jan 16, 2014)

Hey guys. Sorry to revive this old thread but it's a good read. It got me doing a little research of my own on super capacitors. I was looking at some Maxwell units that are the size of a d cell and their rated capacitance is 310 farad at 2.7 volts. Can this be right? Am i missing something?


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## keep_hope_alive (Jan 4, 2009)

Maxwell BCAP3000 is 3,000 Farads at 2.7VDC. Wire six in series for 500F. I have been using them in a variety of builds for a few years with awesome results.


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## moparman1 (Jan 16, 2014)

That's pretty much what i was looking to do. I'm just shocked by the size vs capacitance. I thought i would take up 1/4 of my trunk to do this. That's awesome.


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## gstokes (Apr 20, 2014)

The capacitor is not a complete waste of money BUT it is nothing more than a band-aid for voltage drop, on the same note it reinforces line voltage and makes sure there is a constant unvarying supply..

I invite you to read a thread that was posted at another forum, it is a very heated discussion but if you read through all 5 pages and the accompanying 62 replies you will have a great understanding of what they do and what they don't do..
It is the definitive thread on car audio capacitors and will answer all your questions..

Capacitors, their NOT what some people claim..


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## Victor_inox (Apr 27, 2012)

They are awesome but research safety first, they explode like little bombs. overvoltage is a no no.


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## spyders03 (Jan 5, 2013)

Hence the word "Super" Capacitor. The bigger units "about the size of 1/6 of a car battery) are in the 2200-3500 farad size. The trade off is that they do not hold a charge for very long. After a few days of no use, the voltage would be below a usable voltage.


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## gstokes (Apr 20, 2014)

Here's a link to a 16 Volt / 58 Farad Maxwell BoostCap Module i built last year, I caught a lot of flak but in the end it was me LMAO at the non believers..

58 Farad Super Capacitor for $80 !!


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## nineball76 (Mar 13, 2010)

Mmmm capacitors. Super Caps actually.


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## gstokes (Apr 20, 2014)

Very nice indeed, the 16 Volt 58 Farad BoostCap Module I built the middle of last year is still in use today and works just as good as the day I installed it, right next to my amplifier..
And the 58 Farad statement is not a misprint


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## moparman1 (Jan 16, 2014)

Thanks for all the replies. I haven't read the linked thread above yet but will. 

The intended use; 
I've upgraded my alternator from 83 amps to 120. Two motomaster dry cell batteries connected by 0 gauge. I'm running almost 3000 watts. The alternator has no problem keeping battery voltage up but the batteries can't dump their charge fast enough for high demands.under dynamic passages, i estimate the amps are pulling around 250-300 amps for a split second and that current just isn't available. The leds on the amps will dim slightly and the voltage I'm a dmm will drop a couple of tenths.but i suspect it's dropping much more than that. The meter just isn't quick enough to catch it.I've also measured output voltage at the amp playing music and the highest reading without audible distortion was 20v. This is from my sub amp. Hifonics brx2000.1 @ 1 ohm. I feel it's not putting out the power it can because it doesn't have it available. The cap should be able to dump those large quantities of current into the system to fill in those short deficiencies.


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## patricia (Mar 27, 2015)

ccapehart1980 said:


> okay i recently read an article about capacitors on the web site
> and it was very well writtin and very convincing enough so that i canceled the cap i ordered and or ordered a hi amp alternator instead
> 
> you guys check it out tell me what you think
> Car Audio CAPACITORS: Why They DON'T Work


hey do have limited uses. if you have a alternator that is not keeping up with charging the battery


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## gstokes (Apr 20, 2014)

As i stated above the capacitor (when used in a car audio system) compensates for voltage drop, think of it as a line conditioner but not in the traditional sense, the capacitor is conditioning the line by filling any voids or dips in supply voltage during peak loads such as when the bass hits and there is a surge, line voltage will drop but the split millisecond that line voltage begins to drop the capacitor discharges instantly filling that void, the new hybrid super caps are an amazing piece of technology and you really need to do your research to understand what they do and how they do it..
I was a skeptic like so many others but i have seen the light and now i am true believer, you will be too but first you have to clear your mind and keep it open..

Supercapacitor - Wikipedia, the free encyclopedia

https://www.youtube.com/watch?v=brw6sC8D2_w

https://www.youtube.com/watch?v=z3x_kYq3mHM


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## keep_hope_alive (Jan 4, 2009)

my 2014 Accord has stock electrical - stock alt, stock batt. no big 3 upgrade. 

1/0 from the battery back to the amp rack to a MAXI fuse holder. 100A to the cap bank and 100A to the Audison LRX5.1k.



















volt meter is rock solid, no more than a tenth of a volt change at full volume at idle. 

a high output alt isn't available for the 2013+ accords because there is a CANbus wire to the factory alt for control by the PCM. manufacturers haven't been able to replicate that control yet so the PCM doesn't throw a code. an ultracap bank satisfies my needs and prevents changes to the charging system.


i used a bank of 6 BCAP300 in a 2005 Silverado with 4kW on tap (scoped 4kW clean at 50Hz) with stock electrical and the owner never saw voltage drop below 13.8VDC. the new build will use three banks of 6. similar situation in a 1996 Astro van with 2kW on tap.

many will discuss the pros and cons of something they have never used because they saw threads that said one thing or another. i don't put much merit into them. 

test and report results. 

by using carbon sheets instead of metal foil, actual surface area has increased 3,000 times. capacitance is a function of surface area and distance between plates. that's the main difference. ultracaps have been around for a while and used internationally for a while. they are replacing batteries in many applications where frequent recharging is inherent (i.e. solar or vehicles).


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## TrickyRicky (Apr 5, 2009)

It would of been funny if the guy on the youtube video shorted his bank cap when he dropped it on the metal scale (even though it has a rubber mat on it, if dropped hard enough am sure those bolts can cut through it and touch metal and SPARK SPARK!!)


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## gstokes (Apr 20, 2014)

MetricMuscle said:


> The quality of an amplifier can usually be judged somewhat by how badly it dims the system.


That is an incorrect statement, the lights dim because the amplifier is drawing so much current that it robs the other accessories of their required amperage, the vehicles charging system is overloaded..


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## MetricMuscle (Sep 16, 2013)

gstokes said:


> That is an incorrect statement, the lights dim because the amplifier is drawing so much current that it robs the other accessories of their required amperage, the vehicles charging system is overloaded..


Caps only help for momentary power stabilazation. If there is enough capacitance on the power supply side the draw spike will be handled and there won't be a noticable voltage drop.
This isn't realistic or possible with some huge amplifiers, there isn't room for enough capacitors. I suppose they expect you to use external caps.

If an amplifier does play a continuous low tone and uses a large amount of continuous power then it can cause a voltage drop.

Adding a capacitor will only help if your amp doesn't have enough built in. If you add one and it doesn't help then you didn't have a capacitance issue to begin with.
Small wires leading to the accessories which are effected can also be the problem.


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## gstokes (Apr 20, 2014)

MetricMuscle said:


> Caps only help for momentary power stabilization.
> 
> Adding a capacitor will only help if your amp doesn't have enough built in.


That's all car audio systems have is momentary drops in line voltage so the stiffening capacitor works just fine..

The stiffening capacitor has nothing to do with the internal capacitance and/or power supply, its sole purpose is to maintain line voltage..

In the beginning I had had the same train of thought as you (identical), take the time to read the link i posted, it's the definitive guide to stiffening caps and will explain what they can't do, what they will do and how they do it..
There's a truckload of info in the thread but you need to empty your head before you begin.. :beerchug:


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## knever3 (Mar 9, 2009)

:dead_horse:

How about this, if it feels good, go for it! There are many things that may result in the placebo effect and this may just end up as one! The reason is that since the general public has used current sucking class A/B power for subs for years and once the capacitor was introduced it was sought by the public to "stop your headlights from dimming" and that's how it was marketed. Now every manufacture had to make one, some good, some terribly useless cans of mostly empty shells. It's for the public forum to decide if the capacitor will improve their dynamics of their system.

Someone needs to assemble a lot of these things with a reference system and do trials with a couple of those SMD things showing real-time current draw and voltage sag. Then and only then will the public have an informed decision to apply a capacitor. It will dispel the "I've read this, I've heard this" scenario.


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## gstokes (Apr 20, 2014)

knever3 said:


> Someone needs to assemble a lot of these things with a reference system and do trials with a couple of those SMD things showing real-time current draw and voltage sag. Then and only then will the public have an informed decision to apply a capacitor. It will dispel the "I've read this, I've heard this" scenario.


Tony Candela and Tony D'Amore testing stiffening caps on the SMD AD-1 Amplifier Dyno..

Part 1
https://www.youtube.com/watch?v=eURfjZAVKFY

Part II
https://www.youtube.com/watch?v=nsg8Ys9f6BA

Try not to choke on your Placebo..


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## knever3 (Mar 9, 2009)

Try not to choke on your Placebo..[/QUOTE said:


> Just to clarify, I DO believe in quality caps and they DO have their place in car because many amps are deficient when it comes to capacitance onboard. Some may feel without the proof of said testing they are left with internet search decisions, and thus the placebo effect mentioned.
> 
> Thanks for the link! I think it's funny that Meade was questioned about being in cahoots with Rockford and then he partners with the engineer brain trust behind the Rockford T15k. I am just jealous, I wish I had a tenth of the knowledge that guy possesses in his left arm!


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## moparman1 (Jan 16, 2014)

I don't think that test really proves anything. It's missing one IMPORTANT factor. Music.The AD-1 runs the amp and electrical to the max for several seconds to get its data. This is far more demanding than most music which will only stress the system to that point for a fraction of a second. Apples to oranges.


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## gstokes (Apr 20, 2014)

knever3 said:


> I am just jealous, I wish I had a tenth of the knowledge that guy possesses in his left arm!


Me too!!

Am glad to see a change of heart and added to your reputation


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## gstokes (Apr 20, 2014)

moparman1 said:


> I don't think that test really proves anything. It's missing one IMPORTANT factor. Music.


I edited the original post and added Part 1..

In Part II of the video they test Dynamic Power which is representative of musical peaks..
:beerchug:


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## moparman1 (Jan 16, 2014)

That's rather interesting. Cheers. I'm a little surprised at the results from the 100 farad cap. I guess because it's pulling so much current to hold voltage. ?


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## knever3 (Mar 9, 2009)

moparman1 said:


> I don't think that test really proves anything. It's missing one IMPORTANT factor. Music.The AD-1 runs the amp and electrical to the max for several seconds to get its data. This is far more demanding than most music which will only stress the system to that point for a fraction of a second. Apples to oranges.


They didn't specify in the video but I think that the subs in the vehicle are playing a bass track while measuring with the D'Amore product. If you notice the lights in the car dimming at a certain rate I would only ascertain that the bass is hitting causing a voltage sag whilst measuring burst wattage. It would be nice to see a voltage indication at the amp as well. Then you can have a few more videos on power system upgrades such as the Big Three and an uprated alternator. Heck, you can even use 1/0 wire in comparison to 4AWG wire and even to a lesser extent fuses or circuit breakers inline.

O, to be a fly on the wall for any of his tests, I can't even comprehend what I could pick up. My tiny brain would only retain a portion, but it's the portion I am lacking anyway! LOL!

Edit, since my reply window was open for an hour this post might not be valid..


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## gstokes (Apr 20, 2014)

moparman1 said:


> That's rather interesting. Cheers. I'm a little surprised at the results from the 100 farad cap. I guess because it's pulling so much current to hold voltage. ?


IMHO the 1 Farad Capacitor is too small for a 2500 watt amplifier and showed minimal improvement in the first test but it OWNED the dynamic burst test, would have been more appropriate to use a 3 Farad Capacitor instead of the 1 Farad and those are the results I would love to see, how a properly sized 3 Farad capacitor compares with the 100 Farad unit, I'm betting the results would be more similar..


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