Capacitors? Where's the proof?

[Wingman0121 10+ year member]

Look at all the competitors and people with higher end system. Do they use caps?

I think Steve Meade has two 30 farad caps in one of his SUVs but that thing has like 3 alternators so it probably doesn't matter.

 

[axeten 10+ year member]

That explanation is what i was looking for.

Anyway. I'll bite the bullet and do the battery instead. Looking at the optima yellow top since i can get those here in Australia.

Will do some more searching though.

 

[VWBobby 10+ year member]

Richard Clark has been quoted several times stating that he never added his cap to bolster a weak charging system, but rather to filter voltage anomalies. The difference between this idea, and the more common understanding of a cap as simply a low resistance power supply, is subtle. Subtle enough that most people equate them as the same thing, which leads to the false idea that a cap is a vaible alternative to a sufficient charging system.

That's a good point many people don't think about. Anyone who's listened to a noisy AM radio or CB in a car has heard the pops/clicks, alternator whine, ignition, etc through their system. The only way to help kill the noise is with caps on the offending device... I bet he did it to help all the noise (electrical or audible) of a running car.

Correct me if I'm wrong, but I don't think there were high slew rate batteries available back then? The AGM and other deep cycle batteries we have now can provide the instant power needed for some systems. I think a cap within a few inches of the amp will help a lot more than your typical battery that was available back then? Current can only flow so fast from a lead acid battery.

 

[audioholic 5,000+ posts]

That's a good point many people don't think about. Anyone who's listened to a noisy AM radio or CB in a car has heard the pops/clicks, alternator whine, ignition, etc through their system. The only way to help kill the noise is with caps on the offending device... I bet he did it to help all the noise (electrical or audible) of a running car.
Correct me if I'm wrong, but I don't think there were high slew rate batteries available back then? The AGM and other deep cycle batteries we have now can provide the instant power needed for some systems. I think a cap within a few inches of the amp will help a lot more than your typical battery that was available back then? Current can only flow so fast from a lead acid battery.

You are correct. Also worth mentioning, much of the perceived benefits of adding a cap (my lights stopped dimming as much, etc) is not because a cap specifically was used, but because a power source/storage device was placed very near the amplifier, minimizing voltage loss due to wire resistance. A relatively low ESR batt placed very near the amp would have a much similar effect, with the benefit of additional storage capacity.

 

[VWBobby 10+ year member]

... power source/storage device was placed very near the amplifier, minimizing voltage loss due to wire resistance. A relatively low ESR batt placed very near the amp would have a much similar effect, with the benefit of additional storage capacity.

Another good point I was hinting at. The resistance from the typical 15-20 foot run most people have from the front battery to the amp is enough to tax the charging system... Of course, most people run 0/1 gauge wire to combat the losses, but the wire doesn't have any storage capacity so that's where the cap or extra battery near the amp comes into play.

 

[n2caraudio 10+ year member]

Ok,Silly me bought a capacitor for my system i am about to install, only to hear they are a waste of time and money. I have run one in the past and it stopped my headlights/interior light dimming while using a rockford X6 amp.

I did a search after someone one here said to throw it out, and it seems that many people say they are rubbish, put load on your alternator, dont work, etc etc.....

I can see the concept people are talking about when they say they load up the alternator when the cap is empty (lost charge). But i dont see how this can be worse than not having one. The amp will draw the same power whether from the cap or from the alternator. If the cap is empty the power will go direct from the alternator till the load drops and the cap can charge again......

Anyway, My question is. Does anyone have any sort of figures of amp draw or similar with/without a cap. There seems to be a lot of sarcastic comments and mixed opinions, but in searching i have not found one person that has shown they dont work......

Anyone have any info? At the moment, i will still put it in, since i bought it. I might talk to the sparkies at work and see if we can get some sort of amp draw measurments or something...

How much did that cap cost you?

 

[slim2fattycake 10+ year member]

That explanation is what i was looking for.
Anyway. I'll bite the bullet and do the battery instead. Looking at the optima yellow top since i can get those here in Australia.

Will do some more searching though.

bite the bullet on another battery not optima yellowtops for car audio. they are worth a shit in your hand.

 

[rc10mike 10+ year member]

Huge *****

 

[axeten 10+ year member]

How much did that cap cost you?

Only $90 so nothing too much. My parteners dad got hold of a dual battery kit for me when he installed his so i just need to get a second battery now and i'm set.

 

[helotaxi 5,000+ posts]

Another good point I was hinting at. The resistance from the typical 15-20 foot run most people have from the front battery to the amp is enough to tax the charging system... Of course, most people run 0/1 gauge wire to combat the losses, but the wire doesn't have any storage capacity so that's where the cap or extra battery near the amp comes into play.

More important is that those same people that use 1/0 on the (+) side don't do a thing on the (-) side and use a simple chassis ground. That chassis ground is the weak link pretty much every time.

 

[onelivinlarge 10+ year member]

apon my reserch and questioning a cap is only good if you have the elctrical to back it up and the cap is only useful in a dayly set up... while a battey is even more help full and the reason a cap is not used in comps is because it can not store enough energy or replenish it fast enough for a second burp

 

[audioholic 5,000+ posts]

More important is that those same people that use 1/0 on the (+) side don't do a thing on the (-) side and use a simple chassis ground. That chassis ground is the weak link pretty much every time.

Wasn't it Richard Clark and David Navone that tested a bunch of typical cars like 10 years ago to measure their potential chassis resistance. IIRC, their conclusion was framed vehicles tend to have more potential for passing current thru their chassis efficiently than do unibody vehicles, but even that was not set in stone. Other intangible things like batt location, stock wire type/location, and even the specific design of the vehicle (how panels are joined, where, how well) all factor in to the efficiency of its chassis ground. I believe their final recommendation was if at all in doubt, run a dedicated ground cable.

 

[bubbagumper6 5,000+ posts]

You are correct. Also worth mentioning, much of the perceived benefits of adding a cap (my lights stopped dimming as much, etc) is not because a cap specifically was used, but because a power source/storage device was placed very near the amplifier, minimizing voltage loss due to wire resistance. A relatively low ESR batt placed very near the amp would have a much similar effect, with the benefit of additional storage capacity.

I second that.

 

[06goat 10+ year member]

^^cliffs?

dont use a cap

 

[anwaypasible 10+ year member]

i think this debate is often called upon by people who are willing to let other people speak.

you dont need a large article about the use of capacitors.. and i will show you why below:

first you start up your car and let the capacitor fill up **this event has a name and a value.. making some caps better than others**

then you turn on your radio as you drive down the road.. (does the amp feed from the capacitor or does it feed from the alternator.. or both?)

**this event/threshold has a name and a value.. making some caps better than others**

lets just say for example that the amp is pulling from the alternator as you drive down the road.. the cap is just sitting there all filled up.

then you come to a stop light and the alternator starts to spin much much slower because your engine is idling and the belt that spins the alternator isnt moving as fast.

when this happens, the alternator puts out less electricity.

so the amp ***** up all the electricity that the alternator is putting out and requires more.. this is where your capacitor kicks-in and provides electricity.

how long will the cap provide electricity and how much electricity?

** these events have a name and a value.. making some caps better than others**

if the light turns green before your capacitor gets low on stored energy, then the alternator will start to spin faster as you start driving forward.

and this is a perfect time to explain one reason why your alternator needs to be large.

once you have pressed the gas, the belt that spins the alternator moves faster, and the alternator starts putting out more electricity.

the amp starts ******* electricity from the alternator again and the capacitor recharges itself with whatever electricity is left.

**this event/threshold has a name and a value.. making some caps better than others**

an ideal cap would wait patiently to get recharged and also not require lots of electricity to recharge itself.

because a cap that isnt ideal would **** really hard on the electricity wire and the alternator will suffer from abuse with the amp ******* hard and the capacitor ******* hard at the same time.

its like having a huge amp on a stock alternator.. the amp is going to **** on the alternator until the alternator fails.

if you have a decent size stock alternator.. and your capacitor waits patiently to be recharged.. and your amplifier isnt drawing more electricity than what the alternator can provide (above engine idle) then it's safe to say that your stock alternator isnt going to fail or suffer from abuse.. and you have added a patch to your electrical system that will keep the voltage from dropping while the engine is at idle (that is, until the cap goes dead)

there is no sense with reading those large articles about the results they received when testing their capacitor, because there is no evidence that the capacitor was an ideal capacitor.

the people who wrote the article might have chosen a piece of junk that has all the wrong values for providing voltage at the stop light and slowly recharging after the light turns green.

some caps will wait for the voltage to reach 13v or 12v before it starts to release its stored electricity **again, this event has a name and a value.. making some caps better than others**

these caps will show voltage bouncing around because the cap is waiting.

some caps will not wait for the voltage to reach 13v or 12v.. probably because they are designed to start giving out electricity at a higher voltage.. 13.5v or 14v

and these caps will keep the voltage readout 'stiff' and free from fluctuations as long as the capacitor has energy stored.

how do you know if your capacitor is junk?

if you come to a stop and the lights continue to dim, there is something wrong with the way your capacitor is designed.. try a different brand name or model number.

dont worry too much about the voltage readout bouncing around a little bit, as long as the lights arent dimming, there isnt a solid problem.

the lights are the key piece of evidence you should use to ensure that your amplifier is getting electricity through a thick straw rather than a little one.

i am sorry.. i do not know the names of each event, nor do i know what the ideal values are.

but understand that not all capacitors are made equal.. some offer the same 1 farad value, but perform differently for reasons and examples mentioned above.

***edit***

also understand that there are lots of amplifiers that can run on a stock alternator when the engine IS NOT idling.. which is like 1,000rpm's or higher.

so if your RPM's are 1,000rpm or higher.. the stock alternator can give 100amps or whatever the rating is.

at idle.. the amount of amperage goes way down and your amplifier gets thirsty.

so people suggest that you upgrade your alternator BECAUSE the bigger alternator will put out more electricity when the engine is idling.

the key word here is 'when the engine is idling'

you probably wont use up all of the electricity from a bigger alternator when the engine is at 1,000rpm's or higher.

what you are craving is the power at engine idle.

a capacitor can provide that power at engine idle.. but if your system is too big, you are going to need larger amounts of stored energy.. and that means more recharge when the light turns green.

so it is best to keep your amplifier from getting thirsty.. and whatever electricity is left-over can recharge the caps.