# Super capacitors (good or dumb)



## oabeieo (Feb 22, 2015)

Got turned on to a bank of super caps. Was thinking it looks great as a go between for the batteries and the alternator.

Seems the batteries discharge good for a few min than heat up and can't keep up with the system at full power. Add more batteries and a bigger alt. Done that, but to fully realize the 1/2hour standby power rule I read about I would need hundreds of pounds of batteries . 

I have been told a bank of super caps will be able to charge up way more quickly than lots of car batteries and will take the alt power much more efficiently than just running batteries because the batteries can't charge as fast , so during the non bass heavy parts of songs the HO alt isn't making 100% efficiency re-charging the batteries , but adding a super cap bank will gain 100% of all the residual alt charge ability. Furthermore he explained that the super cap will make the alt last longer because when heavy current demands come so fast with music and a battery in discharge for just a couple min can't meet that so the alt takes a beating and the super caps will buffer that and make the alt more happier and not short out on large instantaneous surges. 

Was this dood full of ****? 

I've been lookin on line and see people starting cars with small 6pk of caps. One guy started his scion 14x on one cap charge and they were tiny cap arrays. 

Would love to do this mod , the weight reduction is tantalizing 
Your thoughts much appreciated 

Cheers,


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## XSIV SPL (Jun 24, 2014)

Nothing is free... Ohm's law... Do the math.

No power conversion I've seen has ever exceeded 98.7% efficiency.

The "dood" is pretty likely full of caca.

I must admit that I have 6 AGM batteries in my own system.


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## Victor_inox (Apr 27, 2012)

XSIV SPL said:


> Nothing is free... Ohm's law... Do the math.


What Ohm law has to do with it, please enlighten me.


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## Victor_inox (Apr 27, 2012)

oabeieo, I have 90 Farad bank but the problem with super caps is that you can`t leave it connected to the battery or it will suck it overnight dry unless car is running.
Best way would be to to use 500A relay completing circuit when ignition is on In that case you`ll have more starting power as side benefit. In fact you can use much smaller starting battery with it.


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## GEM592 (Jun 19, 2015)

This is the old cap issue that has been gone over many times. Many posts already.

I don't think any increased charging efficiency introduced with the cap bank will improve your alternator life.

I don't think caps help your sound, even at high power, and even if slightly so your money (and vehicle space) is better spent elsewhere.


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## lurch (Jan 20, 2014)

" dude " doesn't know how an alternator actually works.


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## DDFusionV2 (Jul 11, 2016)

Super caps have a faster charge/discharge rate than batteries. One day they will replace batteries under the hood


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## nineball76 (Mar 13, 2010)

DDFusionV2 said:


> Super caps have a faster charge/discharge rate than batteries. One day they will replace batteries under the hood


They already do 
http://www.maxwell.com/esm/


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## oabeieo (Feb 22, 2015)

Yeah that's kind of what I got out of it too., dood seem like he really knew a lot, but there was parts of what he was saying that I just have problems with and then I did some scrounging online and really didn't find a whole lot as far as what they do for an audio system I found a lot about them starting cars in replacing batteries it looks like a great idea as far as weight reduction and how are capacitance I would probably do one bank but not much more than that unless I see a real benefit I just wondering what you guys think thanks for all the replies I'm definitely going I want to study more about this if I can just help the bass amp even just a little bit during peak usage and when it's hot out especially it seems like the heat really makes even H output alternator have some problems in regards to efficiency when it's really hot.


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## Eric Stevens (Dec 29, 2007)

The Maxwell Ultra Capacitors used primarily by SPl competitors are really more like a very low DCR battery cell. Batcaps and others have used these as part of there makeup.

The low DCR matters for both charge and discharge current capabilitiy. I think its a good idea and part of a well designed power system when integrated correctly. 

It minimizes losses from cable size when located close to the amplifiers by minimizing peak current levels from the primary power source.

Maxwell Technologies Ultracapacitors and Supercapacitors as a green, alternative energy resource


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## nineball76 (Mar 13, 2010)

Victor_inox said:


> oabeieo, I have 90 Farad bank but the problem with super caps is that you can`t leave it connected to the battery or it will suck it overnight dry unless car is running.
> Best way would be to to use 500A relay completing circuit when ignition is on In that case you`ll have more starting power as side benefit. In fact you can use much smaller starting battery with it.


I've never had an issue leaving them connected and I sometimes go a month or more without starting my vehicles. Supercaps hold a charge very well. Only way they suck a battery down is if they aren't charged and are put in the circuit lower than the battery, which is a very bad idea. Always charge a bank to as close to your battery voltage as you can get before connecting them.


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## oabeieo (Feb 22, 2015)

Eric Stevens said:


> The Maxwell Ultra Capacitors used primarily by SPl competitors are really more like a very low DCR battery cell. Batcaps and others have used these as part of there makeup.
> 
> The low DCR matters for both charge and discharge current capabilitiy. I think its a good idea and part of a well designed power system when integrated correctly.
> 
> ...


Thank you! 

Yeah, I'm like all into getting the charging system up to par. The maxwell is what I was looking at. The "D" cell size boards with balancing circuit . There's one I saw on eBay , nice enclosure, 4GA wires luged on and grommet out. Wanted to do like victor said, put them on a hiAmp relay like a stinger battery isolator , have one array at front battery and one near amps. This combined with the three small Xs power xp750s I have now and maybe if I feel like it's safe a Xs power lithium.


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## oabeieo (Feb 22, 2015)

nineball76 said:


> I've never had an issue leaving them connected and I sometimes go a month or more without starting my vehicles. Supercaps hold a charge very well. Only way they suck a battery down is if they aren't charged and are put in the circuit lower than the battery, which is a very bad idea. Always charge a bank to as close to your battery voltage as you can get before connecting them.


A 16v array will always try to charge to 16v. Hooked to a battery it will leak down. Un hooked it will hold its standing voltage. (Whatever that may be) 

At least if they work like a normal cap I think that's how it works ~victor?


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## SPLEclipse (Aug 17, 2012)

The voltage rating on a cap is it's maximum charging voltage. They will hold whatever voltage they are exposed to. When you turn the car off if the caps are at 14.4v, they will discharge into the battery until equilibrium has been reached at roughly the resting voltage of the battery.

I don't see a reason to run caps if you want more key-off listening time. If you want hundreds of amps of current for a few seconds with the key off and the ability to recharge quickly they are great - which is why they are great for SPL.


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## Victor_inox (Apr 27, 2012)

Battery capacity is many times more of that supercap.supercap charged by alternator to whatever voltage it supplied,then when car is off battery started taking that overvoltage and draining the cap.that how it works in mine and in theory.

I don't see a problem in using isolator to prevent dead battery.


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## Locomotive Tech (May 23, 2016)

Simple capacitor use for buffering a battery? - Electrical Engineering Stack Exchange

Did a little math, damn! sure seems like a lot of caps. Seems like a dual alternator set up would be more robust?


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## Snake (Aug 28, 2015)

Another problem with capacitors is that there voltage drops steadily drops when energy is removed from them, which means only a small amount of energy is in the usable 14.4-12.8v range for car audio. This makes an absurd amount of capacitance necessary for it to be useable.

One good use for capacitors in car audio is noise suppression, and I picked up a 2 farad electrolytic cap for this purpose. Put in parallel as close to amps as I can, the .01 ohm resistance of the wire running from the front makes a 8hz 6db/Oct lowpass filter. This removed the alternator whine I was getting, and also lowered the noise floor abit. A larger capacitance would only drive noise lower, but only to a point where the amps noise floor would become the main source of noise.


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## T3mpest (Dec 25, 2005)

Super caps are nothing new in the SPL world. Guys have been using them for years now. A good bank of 6 caps will more or less replace a single group 34 for daily useage. 


How low does your voltage dip now? What kind of draw do you have? Caps have an advantage on batteries in that they start to help immediately, they charge at your alts level. Batteries need to be drained down to about the float point of the battery before you really get into their reserve. The caps will act as a buffer, keeping you in the 13-14v range for much longer.

Still, if the alt isnt' keeping up, I'd expect you'd need 2 more banks before they gave you enough reserve to really keep you in the 13-14 range on music. 

Or are you talking car off? Because caps won't be doing any good in that case.


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## oabeieo (Feb 22, 2015)

Victor_inox said:


> Battery capacity is many times more of that supercap.supercap charged by alternator to whatever voltage it supplied,then when car is off battery started taking that overvoltage and draining the cap.that how it works in mine and in theory.
> 
> I don't see a problem in using isolator to prevent dead battery.
> 
> ...


The problem is the heat and battery's ability to recharge and discharge. Every system I've ever had always had two good sized batteries. Never been into thousands of pounds of batteries . The batteries do great for the first few minutes of high current discharge , but even after turning the system down for a few minutes it takes hours for the batteries to level back out and need a float charge. When it's hot out everything just sucks as far as keeping batteries able to supply a bass amp as small as 1k. Seems the caps are a viable way to augment these common-problems.


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## oabeieo (Feb 22, 2015)

T3mpest said:


> Super caps are nothing new in the SPL world. Guys have been using them for years now. A good bank of 6 caps will more or less replace a single group 34 for daily useage.
> 
> 
> How low does your voltage dip now? What kind of draw do you have? Caps have an advantage on batteries in that they start to help immediately, they charge at your alts level. Batteries need to be drained down to about the float point of the battery before you really get into their reserve. The caps will act as a buffer, keeping you in the 13-14v range for much longer.
> ...


The alt keeps up when it's cool outside. And the three Xs power batteries work just ok. It works, no voltage drop on a 250A alt running 3kw. When it's hot out, the sub amp gets weak after 15-20min than starts to shut down. (1200/1 HD) and the 600/4 and focal amp get weak and loose power. Voltage dips aren't that big during peak bass notes 13.5 I don't let it go below that, 

I need something that will charge FAST! And discharge fast repeatedly regardless of ambient temp, and won't cycle and require a dam float to prevent sulfation. Somtething that has enough capacity to last a song at the minimum. Just getting through one song when it's hot out seems like a challenge , I listen very loud to some. Concert levels usually , The caps seem like a good idea. We're talking farads in the hundreds tho , not just a few.


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## T3mpest (Dec 25, 2005)

oabeieo said:


> The alt keeps up when it's cool outside. And the three Xs power batteries work just ok. It works, no voltage drop on a 250A alt running 3kw. When it's hot out, the sub amp gets weak after 15-20min than starts to shut down. (1200/1 HD) and the 600/4 and focal amp get weak and loose power. Voltage dips aren't that big during peak bass notes 13.5 I don't let it go below that,
> 
> I need something that will charge FAST! And discharge fast repeatedly regardless of ambient temp, and won't cycle and require a dam float to prevent sulfation. Somtething that has enough capacity to last a song at the minimum. Just getting through one song when it's hot out seems like a challenge , I listen very loud to some. Concert levels usually , The caps seem like a good idea. We're talking farads in the hundreds tho , not just a few.


If the amps are shutting down when it's hot out, if voltage still isn't going below 13.5, I'd be looking at adding fans as that sounds more like thermal protection from running them hard than it does low voltage protection.

If it somehow is low voltage, adding caps won't fix it. If the alt isn't keeping up during the heat, it won't be able to properly charge the caps and they will QUICKLY run out of juice in that kind of scenario.

Still, I'd look at ventilation before I did anything else, amps dont' kick off at 13.5 due to low voltage.

For caps, Maxwell is the gold standard. If you only charge to 14.4 tops you can get away with 5 of the higher farad ones and get the max reserve for the bank size.

XS makes caps too, not quite as nice, but still good and priced nicely.


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## oabeieo (Feb 22, 2015)

T3mpest said:


> If the amps are shutting down when it's hot out, if voltage still isn't going below 13.5, I'd be looking at adding fans as that sounds more like thermal protection from running them hard than it does low voltage protection.
> 
> If it somehow is low voltage, adding caps won't fix it. If the alt isn't keeping up during the heat, it won't be able to properly charge the caps and they will QUICKLY run out of juice in that kind of scenario.
> 
> ...


 The amp getting hot was the first thing I thought of that that's not it it's definitely the batteries after a little bit They loose there hi amp. Cca rating is only for 30sec. After that batteries cca goes to less than 100A continuous . 

I just ordered two banks of maxwell caps. Each bank has 12 500F caps. Totaling 180F. I guess we'll see how it works out if it doesn't do what I want I'm going to get the XS lithium


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## nineball76 (Mar 13, 2010)

T3mpest said:


> XS makes caps too, not quite as nice, but still good and priced nicely.


Well xs puts new labels on caps. Rebranded ioxus caps. 

Know where a person could find the new maxwell 3v 3000F caps? Google isn't returning anything but the 2.7v ones.


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## oabeieo (Feb 22, 2015)

Gang, read this page.


Powerful alternators for auto sound


Read ALL of it. There's a lot of reading and info on this page . It will not ale about 5min but it really explains exactly my feelings. When I went looking for info I stumbled on this page after I already got a HO alt installed. I'm not trying to endorse there product but they speak truth on here. A HO alt when hot put out a fraction of its rated output. This guy really says it in a way that I feel is agreeable, and furthermore explains why I am experiencing this after my upgrades. All of my previous systems were ****ty compared to when it is freezing out. Anyway a dam good read. Check it out


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## Jscoyne2 (Oct 29, 2014)

oabeieo said:


> Gang, read this page.
> 
> 
> Powerful alternators for auto sound
> ...


Whats your thoughts on super caps today?


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## oabeieo (Feb 22, 2015)

Jscoyne2 said:


> Whats your thoughts on super caps today?


Today, 

Same that I can remember 

I have a bank of caps , higher exchange rate than batteries, need at least one starting battery..

Unless a 400lb battery bank is used , a cap bank can exchange power faster and more efficiently.... when every A of storage matters 

Otherwise , not a big deal


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## Jscoyne2 (Oct 29, 2014)

oabeieo said:


> Today,
> 
> Same that I can remember
> 
> ...


Thinking of getting something like this as a buffer against that pesky headlight dimming.









Limitless Super Caps 2.7V 3000F bank of 6


High quality high discharge Lithium Batteries for Car audio 12 volt stereo systems




limitlesslithium.com


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