# 100 farad capacitor?



## illnastyimpreza (Oct 25, 2006)

ok I'm running a 1.5 farad cap right now. And I have no idea if it even does anything.

But I am going to be upgrading to a little more power (700w front stage, 500w substage, 500w midbass-subbass , and yes my biggest driver is only 8'' )

And I was wondering if a capacitor would really even do anything for me?
Wouldn't just throwing a yellowtop battery in the trunk do more?

what REALLY are the benefits of using a capacitor???

I have spent alot of timing desining my system, and realized that I never even thought about one...

http://cgi.ebay.com/LANZAR-OPTICAP1...ryZ75388QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## dawgdan (Aug 10, 2006)

The SPL guys claim that a capacitor is just a band-aid for a bigger problem - not enough amperage from the electrical system. Going to a high-output alternator should help most, according to that school of thought.. 

That being said, I've never used either. I haven't seen any signs of excessive current draw.


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## cam2Xrunner (Apr 30, 2005)

....



> After studying a little history on large 1 Farad capacitors in car audio, you'd be amazed that they even sell at all. How useful are they? What do they really do? Will a Cap 'improve' my sound quality? Will it Prevent my lights from dimming? Will it audibly affect my audio system in any way?
> 
> Before you get the truth to any of the above questions, chances are, you've probably spent $100 or more on one of these devices. However, let's study a little history regarding this issue.
> 
> ...


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## HIS4 (Oct 6, 2005)

I'm going to have to agree and disagree with some of that post as some points mentioned there are such gross overgeneralizations.

Rather than get into the technical aspects of how a cap works and how it compares to say a 2nd battery in parallel to the starting battery I'll just state the following:

1. A cap will never improve the sound quality of your system.

2. A cap will not fix the problem of an undersized electrical system.

3. The charging and discharging characteristics of a cap is very different from a battery.

4. A system with amps that are rated to draw 200A will never draw 200A while playing music.

5. A cap can help remedy headlight dimming in certain cases.

6. A high output alternator is not always the best solution.


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## tard (Jul 13, 2006)

the "old school" dielectric caps aren't the thing to go with. like stated, batteries have a surface charge that can be quantified to capacitance. and there are batteries that charge and discharge super fast these days. putting a battcap or the kinetic, or one of the likes, close to the amps would be a better idea. if you have the space, you can just go ahead and put a good battery close to your amps. a good "dry cell" type is my favorite.

the old idea of 1 farad for 1000w is not good enough. if you want to make a good diff, it needs to be more like 1 farad for every 10 amp draw. which can be in the form of another battery, or a whole trunk of 1 farad dielectric's. but everything needs to be considered on the whole. it's amazing how good a stock alt can do with a good battery and huge + and - wires to feed the amp. and not a simple body ground with a thin ring terminal on a 2kw amp.

sure, a battery has to be charged back up just like a "cap" and caps can charge quickly. but like noted, there are some really good manufacturing techniques of batteries (low esr).

that's my soapbox about it.


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## illnastyimpreza (Oct 25, 2006)

ok thats pretty much what I thought.... Look like I'm gona be doing the "big 3 " and upgrading to some knukonceptz 1/0 gauge all around... thanks guys


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## Whiterabbit (May 26, 2006)

The real benefit to the capacitor is the Electrical Series Resistance which allow for speedy delivery of current. But those big bad many-farad caps are usually made from alternate materials which drive ESR up.

They can't possibly benefit your stereo better than your standard super-low-ESR 1 farad cap models.


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## Preacher (May 8, 2006)

Wouldn't a cap help eliminate possible noise (hums)?


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## tophatjimmy (Dec 16, 2005)

How about we just start putting caps in line with the headlights instead of the amplifiers? That'll fix the dimming right?


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## tard (Jul 13, 2006)

lol, that's a good one.


i wonder how many people will think about doing that not knowing any better.


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## bdubs767 (Apr 4, 2006)

a firend of mine put it ont he headlights and it does work....as for people who say caps dont work...why the hell are they in amps then?

But caps are used with the wrong intention in about 99.9% of installs


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## Pb2theMax (Aug 26, 2005)

IMO, you will get better results by beefing up your alternator, battery, and wiring. Add bigger or extra grounding and charging wires in the engine compartment. 

I'm running approximately 2400 watts RMS. Stock 130 amp alternator, Optima battery, upgraded wiring, NO caps, no dimming lights, even when playing bass CDs. My voltage drops a maximum of .2 volts when the bass hits.


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## Whiterabbit (May 26, 2006)

I love how everyone recommends $500 worth of stuff as a better alternative to what can cost $20 on ebay.


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## thatvan (Aug 29, 2006)

I still like Geolemons decemination of the topic:

http://www.betteraudio.com/geolemon/newmain/battcapalt/


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## chad (Jun 30, 2005)

bdubs767 said:


> a firend of mine put it ont he headlights and it does work....as for people who say caps dont work...why the hell are they in amps then?
> 
> But caps are used with the wrong intention in about 99.9% of installs



The big caps in amps are usually after the PS in Bipolar land where they cant be drawn from by other accessories in the car.

Chad


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## illnastyimpreza (Oct 25, 2006)

thatvan said:


> I still like Geolemons decemination of the topic:
> 
> http://www.betteraudio.com/geolemon/newmain/battcapalt/


I think thats the best description I have heard...in a nutshell....


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## tard (Jul 13, 2006)

i don't think it was mentioned clear enough in that link (or maybe i read a little too fast), is that a cap placed any where in the system will discharge to anywhere in the electrical loop in the vechicle. there are going to be some draw backs to the current going back long runs of wire, or wires a little smaller than desired.

think of volts as pressure. where ever there's a point of higher pressure in the system, it's going to equalize over to the area of lower pressure.


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## GMo (Aug 9, 2005)

That web page is pretty vague and has a non-related explanation for capacitors.

The diagrams have no relevance to reality, and the order on that page of electrical "upgrades" is pretty illogical.

There are no good pages describing capacitors and their influence on the electrical system that I've ever seen. 

A capacitor may influence the electrical discharge and load rates, but for any modern alternator (80+ amps) someone is going to need a massive capacitor with ultra low equivalent resistance at a low duty- 50-100hz (and practical equivalent impedance) to have any real effect on the electrical system. Good luck finding one of those.

The capacitors in amplifiers are implemented for very low current relative to voltage. It's very different than stiffening capacitors, which deal with very high current relative to voltage.


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## thatvan (Aug 29, 2006)

GMo said:


> That web page is pretty vague and has a non-related explanation for capacitors.
> 
> The diagrams have no relevance to reality, and the order on that page of electrical "upgrades" is pretty illogical.


I love these “provocative” subjects!  

Maybe it’s just me, but I think the site has a very good description, in layman’s terms, of ways to upgrade ones electrical system. 

What is illogical about the upgrades and the order in which they are presented?


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## GMo (Aug 9, 2005)

Just by glancing over the page these are 2 major problems, I'm sure there are more:


BETTERAUDIO said:


> A capacitor is added because batteries are slow to give up charge, relatively speaking, and are slow to recharge, where capacitors are nearly instantanious.
> Think of it like eliminating a speed bump in the road.


A typical car battery has a reaction rate under a millisecond. Human visual/audible perception is limited to about 1/20 of a second. External resistances (wiring/grounding/amplifiers/etc) are what regulate the discharge rate of a source. So speed of the sources really has nothing to do with this.



BETTERAUDIO said:


> In addition, it puts a higher drag on your engine, which reduces your horsepower at the wheels and accelleration, it is expensive, and it might not even be avaliable for your car, depending on what car you have obviously.
> They are also tricky to shop for, because you don't want to end up with a "200 amp" alternator that in reality produces the same or lower output current at idle.
> But obviously, the benefits are that a good one can produce more current any time the car is running, if you do fall into the category who needs this.
> Realistically though, that's not the majority- there are a whole number of interesting factors to consider though, including not just the wattage of your amps, but your listening habits, the "duty cycle" of the bass that you are playing, recording levels, volume levels, and your batteries recharge/discharge rates and the "duty cycle" there, also...


An alternator's reaction rate is around 2-4ms. Bass is defined by it's duty cycle, someone can't call 3,000hz of an output signal bass. Bass is the load causing the major Vdrop. Thee frequencies are around say 40-120hz, which contribute the most. So a properly sized alternator can discharge "fast" enough into the load; wiring, grounding, proper alternator size, and external components are the major factors determining if the discharge matches the load.

- A capacitor could never cover the shown bass load from T1-T3 in the graph.

- Upgrades 1-2-wiring- are great. #3-capacitors isn't needed, but even if someone were to think it was, it should be added for reducing ripple and shouldn't be a number. #4- battery # increase- isn't going to stop voltage drops from 14.2V to around 11.xx volts. Someone should be upgrading alternator before they start adding batteries, and should only add batteries to listen to music w/ the car off or if their load duty is greater than their source duty. 

Nothing against whoever wrote this page, but it’s not factual or relying on realistic principles. It’s just his/her opinion on the subject.


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## mvw2 (Oct 2, 2005)

A cap can buffer and smooth out the current. They are used in amp to buffer the "noisy" voltage from our car's electrical system.

There are purposes for them, however, it's not really what people think or better yet what marketing tells them.

There just isn't that "I get mad pounding bass yo cause I run a 100F cap." 

The idea of induced resistance should be well understood too. At some point as you run larger caps, you start to raise the resistance to a counterproductive level. You actually build a bottleneck into the system.


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## ChiTownSQ (Apr 7, 2008)

mvw2 said:


> A cap can buffer and smooth out the current. They are used in amp to buffer the "noisy" voltage from our car's electrical system.
> 
> There are purposes for them, however, it's not really what people think or better yet what marketing tells them.
> 
> ...


Resurrected.....


Here is my question, or answer, or opinion, im not sure yet...

I have 20 farad Powercore, had it for years and in my last 5 systems. When I get out my spl mic on my Audio Control Spectral Analyzer, I am able to achieve 1.5 more DB with the Capacitor installed. I am also allowed to go 2 more clicks up on my volume control with out audible distortion coming through my speakers? I don't know the numbers, but I know that these are my notable changes from having the 20 farad capacitor installed in my system. If I can get the same thing from an extra battery in the car, so be it. Ill Take my Power Core.

So tell me again, it really really does not do anything? Ohh and my headlights don't dim any more too. That is fact, not marketing.


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## da Vinci (Jun 10, 2009)

GMo said:


> That web page is pretty vague and has a non-related explanation for capacitors.
> 
> The diagrams have no relevance to reality, and the order on that page of electrical "upgrades" is pretty illogical.
> 
> ...



Found one.


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## da Vinci (Jun 10, 2009)

ChiTownSQ said:


> Resurrected.....
> 
> 
> Here is my question, or answer, or opinion, im not sure yet...
> ...



If you do the math, A 1 farad cap help a 1000 watt stereo for about a half a second. You need larger caps to notice a difference, this is why there are so many arguments over it. If implemented properly they do make a difference, but you need 10's of farads at a minimum with a ultra low esr and proper duty cycle. We are just now in an age where this technology is becoming cheaper because of the implementation of ultra-capacitor technology in hybrid vehicles... which is where my cap comes from. A Maxwell Technologies 500 farad ultra capacitor module.


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## Austin (Mar 12, 2009)

is that a 504 farad cap?? god damn


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## dbiegel (Oct 15, 2006)

Another thing to keep in mind is that a large cap is yet another load on your electrical system during any time that it's not fully charged. Two steps forward, one step back? ...Or perhaps even one step forward, two steps back


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## I800C0LLECT (Jan 26, 2009)

I'm not sure if this helps anybody but the only purpose I see for a CAP is to help keep a clean signal to the amps for longevity.

In overclocking CPUs, stable power and mitigating ripple is a big deal. That's why I use a cap with amps. But, at the same time...electrical systems and batteries are far better in todays standards.


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## MarkZ (Dec 5, 2005)

da Vinci said:


> If you do the math, A 1 farad cap help a 1000 watt stereo for about a half a second.


Yeah, so? Most transients are shorter than that.



dbiegel said:


> Another thing to keep in mind is that a large cap is yet another load on your electrical system during any time that it's not fully charged. Two steps forward, one step back? ...Or perhaps even one step forward, two steps back


This was addressed in another recent cap thread. It's only a load while recharging, which basically only happens in between transients -- ie. when current draw isn't much of an issue. So the "load" argument doesn't really work for two reasons: 1) most capacitors aren't very lossy; 2) capacitors recharge as a function of system voltage -- when the system voltage rises, it's because the draw is reduced or there's a rebound effect.



1800COLLECT said:


> I'm not sure if this helps anybody but the only purpose I see for a CAP is to help keep a clean signal to the amps for longevity.
> 
> In overclocking CPUs, stable power and mitigating ripple is a big deal. That's why I use a cap with amps. But, at the same time...electrical systems and batteries are far better in todays standards.


Not such a big deal with car amplifiers. They've already got filter caps on the input of the power supply to do that. And some of the more sensitive devices will be exposed to another level of capacitance in the form of rail decoupling capacitors on the secondary of the transformer. In fact, they probably do a better job of it because their positioning in the circuit reduces ESR and ESL. Besides, if you really want to get rid of ripple, the bypass capacitor approach might be the better one. And ginormous external caps aren't very effective in that department.


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## I800C0LLECT (Jan 26, 2009)

Great info...appreciate that 

Ignorance always leads you down a different road. That's what these forums are for. *good game*


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## SlipAngle (Oct 2, 2009)

da Vinci said:


> Found one.


That is some serious hardware you have there. Which hybrid vehicle was it originally designed for?


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## 14642 (May 19, 2008)

Sometimes the audio industry makes me feel like I'm wrestling the guys from "The Big Bang Theory" in an inflatable pool full of snake oil.


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## illnastyimpreza (Oct 25, 2006)

Andy Wehmeyer said:


> Sometimes the audio industry makes me feel like I'm wrestling the guys from "The Big Bang Theory" in an inflatable pool full of snake oil.


:laugh:


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## WRX/Z28 (Feb 21, 2008)

cam2Xrunner said:


> Quote:
> After studying a little history on large 1 Farad capacitors in car audio, you'd be amazed that they even sell at all. How useful are they? What do they really do? Will a Cap 'improve' my sound quality? Will it Prevent my lights from dimming? Will it audibly affect my audio system in any way?
> 
> Before you get the truth to any of the above questions, chances are, you've probably spent $100 or more on one of these devices. However, let's study a little history regarding this issue.
> ...


It's hillarious that I think I still have a 1 farad cap from back in the day with Richard Clark and David Navone's names on it. That cap was made by monster cable. It's amazing that he now lambastes those who make and sell caps today, especially being that according to this article, he's the one who started the trend.  :laugh:


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## Qicker306 (Oct 2, 2009)

A cap charges and discharges fast where as a battery charges and discharges slowly. I think caps are dumb, do the big 3 and get a good battery, higher quality batteries are capable of charging and discharging faster then your Walmart battery. I had 1350W RMS off of a stock '00 Neon w/ a 80A? alternator and a Walmart battery, lights would shut off completely when cranked up. Alternator was probably actually more like 60A, alternator some how lasted a year and a half 'till the car got totaled off.


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## chad (Jun 30, 2005)

Andy Wehmeyer said:


> Sometimes the audio industry makes me feel like I'm wrestling the guys from "The Big Bang Theory" in an inflatable pool full of snake oil.


damn I'm already using one of yours, I may have to update.


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## 86mr2 (Apr 29, 2005)

Andy Wehmeyer said:


> Sometimes the audio industry makes me feel like I'm wrestling the guys from "The Big Bang Theory" in an inflatable pool full of snake oil.


Well, keep fighting the good fight and coming up with these quotable nuggets!


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## vincywiz (Oct 21, 2009)

Yeah...you've nailed it down correctly. As an Insider, I know what you're saying. The real problem (in my opinion) is that Car audio companies (wholesalers called manufacturers) are NOT very serious about the quality of the goods they sell; there's no love or passion except for $ and that's the problem.


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## vincywiz (Oct 21, 2009)

I don't know what anyone would see to disagree with in this post...but then again, the post is obviously based on sound technical knowledge / know-how, so if your knowledge is not sufficuent, then I can understand. I am an EE (ieee 08895054) and 100% of everything posted is accurate, as far as the bill of goods sold to Endusers, extolling the usefulness and even magical powers of a cap. Note well that the poster didn't even address the grossly over rated FARD numbers posted on these devices. Botton line is this; a cap is a passive device (cannot generate it's own power) and when it's discharged, it becomes an added load on the Alternator for as long as it takes to be recharged, although that may be m-seconds, the point is that in an overloaded system, even milliseconds count. Think of it this way, a car was never dsigned to power an additional 2000 watt device, so if you added a 2000 watt amp. you should also increase your power source (alternator) by 2000 watts (2000/12.5 = 160 amps x 2 assuming the amp is 50% efficient)....IF you want your car to continue performing as it should and then you won't need caps.


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## MarkZ (Dec 5, 2005)

vincywiz said:


> I don't know what anyone would see to disagree with in this post...but then again, the post is obviously based on sound technical knowledge / know-how, so if your knowledge is not sufficuent, then I can understand. I am an EE (ieee 08895054) and 100% of everything posted is accurate, as far as the bill of goods sold to Endusers, extolling the usefulness and even magical powers of a cap. Note well that the poster didn't even address the grossly over rated FARD numbers posted on these devices. Botton line is this; a cap is a passive device (cannot generate it's own power) and when it's discharged, it becomes an added load on the Alternator for as long as it takes to be recharged, although that may be m-seconds, the point is that in an overloaded system, even milliseconds count.


As you mentioned, the cap is a passive device. Moreover, it's not consuming power. So, even though it acts like an "added load" while recharging, it actually REDUCES the load while discharging. There's no net gain/loss as far as behaving like a load goes.


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## vincywiz (Oct 21, 2009)

MarkZ said:


> As you mentioned, the cap is a passive device. Moreover, it's not consuming power. So, even though it acts like an "added load" while recharging, it actually REDUCES the load while discharging. There's no net gain/loss as far as behaving like a load goes.



That's a fair response; but in the interest of keeping this forum informed, I wish to educate you a little more in Electrical Engineering principles and I hope you don't mind because it's being done with love:
In order to determine whether a discharged cap. is seen as a load by a charging circuit, I invite you to do a little experiment. 
connect an incandescent lamp between the + terminal of your discharged cap. and the B+ terminal of the battery. Watch what happens when you connect the B- (negative terminal) between the cap. and the battery; the lamp glows brightly at first and then gradually glows dimmer as the cap. retains more & more charge right...do you know why?


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## MarkZ (Dec 5, 2005)

vincywiz said:


> That's a fair response; but in the interest of keeping this forum informed, I wish to educate you a little more in Electrical Engineering principles and I hope you don't mind because it's being done with love:
> In order to determine whether a discharged cap. is seen as a load by a charging circuit, I invite you to do a little experiment.
> connect an incandescent lamp between the + terminal of your discharged cap. and the B+ terminal of the battery. Watch what happens when you connect the B- (negative terminal) between the cap. and the battery; the lamp glows brightly at first and then gradually glows dimmer as the cap. retains more & more charge right...do you know why?


I can do without the condescension. Make your point.


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## vincywiz (Oct 21, 2009)

MarkZ said:


> I can do without the condescension. Make your point.


Sorry! I wasn't trying to be...my sincere apologies. 
If the cap. wasn't acting as a load, "0" current would flow and the lamp. would not light. If the lamp was a fuse, it would blow and we both know that a fuse only blows when excessive current is consumed by the load connected to it.


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## vincywiz (Oct 21, 2009)

MarkZ said:


> I can do without the condescension. Make your point.


BTW, we are BOTH NYER's..maybe that's why we can't agree?


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## chad (Jun 30, 2005)

vincywiz said:


> Sorry! I wasn't trying to be...my sincere apologies.
> If the cap. wasn't acting as a load, "0" current would flow and the lamp. would not light. If the lamp was a fuse, it would blow and we both know that a fuse only blows when excessive current is consumed by the load connected to it.


the lamp should eventually extinguish, IF it does not then it means that the current limiting of the illuminated filament is not allowing a full charge. it's a weird test due to the non-linear dynamics of a light bulb. Best bet is to charge it, THEN place the lamp in series, this will tell you if the cap is acting as a static load.


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## MarkZ (Dec 5, 2005)

vincywiz said:


> Sorry! I wasn't trying to be...my sincere apologies.
> If the cap. wasn't acting as a load, "0" current would flow and the lamp. would not light. If the lamp was a fuse, it would blow and we both know that a fuse only blows when excessive current is consumed by the load connected to it.


That's not what a load is. Current alone does not define "load". Otherwise, a source would also be a load, but it isn't. A load is something that dissipates energy. A cap does not dissipate energy.

When it draws current, it looks like a load. That is, the source (ie. alternator) thinks it's a load. BUT...the cool thing is that the cap delivers just as much current as it draws. So, sometimes it looks like a load, and other times it actually makes the real load (the amplifier) look like less of a load than it is. That's because the cap discharges current into the amplifier, assisting the alternator. At the end of the day, it's a zero sum game.

If you were to tally up the amount of current drawn from the alternator with and without a cap, it would be the same. The current waveforms wouldn't look the same, but the integral of those waveforms would be the same.


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## Austin (Mar 12, 2009)

MarkZ said:


> At the end of the day, it's a zero sum game.
> 
> If you were to tally up the amount of current drawn from the alternator with and without a cap, it would be the same. The current waveforms wouldn't look the same, but the integral of those waveforms would be the same.


I agree completely.


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## niko084 (Dec 16, 2009)

tophatjimmy said:


> How about we just start putting caps in line with the headlights instead of the amplifiers? That'll fix the dimming right?


This is an old thread..

But I figured I would comment on this one.

Actually I DID put capacitors in my headlamp harnesses.

Reasoning as follows.

I have HID's, when I turn on my lights or fog lamps (also HID's) my stereo will make a sudden pop sound and my dash will flicker as they power up.

Placing a 35v 1000uf capacitor in the main power line going to each ballast this completely nullified the issue, just a small buffer for that surge as they power on, now we are talking about a 35w ballast here, NOT a 1000w amplifier.

Now onto the next area about this beyond what has already been discussed.
If your charging system cannot keep up with your amps, guess what it's not doing a great job at keeping the capacitor charged either while the stereo is cranked.

I cannot count how many times I have told people to stop buying capacitors and buy a new alternator and/or better battery, I also cannot count how many didn't listen and were pissed and how many listened and were very pleased.

I do also occasionally put a small capacitor in line with my head unit, I have had issues with them losing memory as you start the car from time to time. This is pretty rare if you have a good battery but can happen in some cases with after market head units if you use the factory harness. In this sense a capacitor helps as well, generally once again a small one.


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