Caps are ghey

[namster44 10+ year member]

Do you guys remember where the article/experiment with the caps is? I can't find it, I search so freaking long, that I hoped someone would have bookmarked it. It's the one with charts saying there's not significant advantage using a cap. Heck, any article saying caps are bad, would help, I'm trying to teach some nublets.

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[maylar 10+ year member]

http://www.welcometotheden.8k.com/caraudio/Captest.pdf

 

[namster44 10+ year member]

you sir are the man. I knew you of all ppl would keep this handy.

 

[RoseMarysBaby 10+ year member]

wow thats crazy. The caps actually hurt the system.... :thumbsdow

 

[bigwheel15 10+ year member]

**** caps, allways causing trouble.

 

[helotaxi 5,000+ posts]

wow thats crazy. The caps actually hurt the system.... :thumbsdow

Sure it would. If you cannot keep from dipping into the battery (the battery may not fully discharge but it will be getting partially discharged and recharged) then adding a cap will not help and will actually hurt. He's running 2000W off a 80A alt and running the amp to clipping. The test would be a lot more valid in my eyes if he either 1) run an alt comensurate with the size amp he was running if he was going to run it at full power for an extended time or 2) ran an amp that was more reasonably sized or 3) played the volume at a listenable level. Under one of those above conditions I might consider this a valid test, and I've a feeling that the results might be a bit different. All the "test" in that link showed was that a heavily taxed charging system will not benefit from a cap (duh) but when you then make the blanket statement that caps are not ever going to help based on that one test that's just stupid.

 

[gregus 10+ year member]

Lol, saying caps don't help is just plain redicolous!!! Of course they help! They are much closer to your amp than the battery, and they deliver power alot quicker than the battery does, even alot quicker than the battery would if it was real close to your amp! I've tried my system with and without a cap, and if u have a high-powered amp that requires alot of power, you'll definitely benefit from the use of a cap! No doubt whatsoever!!!

 

[Radar 10+ year member]

^^^

What is ridiculous is your statement. You provide no real scientific evidence to back up what you said. Closeness from the amp to the battery doesnt mean crap. Over a huge distance of say hundreds of yards or miles yeah maybe, but within the space of a car it doesnt mean anything. Just because you 'tried' your system with and without a cap doesnt mean crap. What did you 'try'?There is no actual way you would be able to tell an audible difference between the 2. It may have helped stopped your dimming, but it only just covered it up not fixthe problem underneath it.

 

[helotaxi 5,000+ posts]

It does discharge quicker than a battery, however it fully discharges in a very short time so any prolonged bass notes (i.e. most modern music, especially rap) is going to cause the voltage to drop more than if there were no cap at all

Not entirely accurate. As long as there is another device (battery mostly) providing current to the mix, a cap will never FULLY discharge. It will discharge to the voltage level of the battery but that is really only a fraction of the total carge on the cap. Once it has discharged, it must be recharged and the recharge will keep the voltage from returning to its maximum for the short time it takes the cap to recharge.

The proper use of a STIFFENING cap is to provide near instantaneous current for the brief period of time (tiny fraction of a second) when the current demand of the amps changes from a low demand to a high demand when the alternator can provide enough current for the higher demand but the ESR of the alt keeps it from doing so quickly enough. During the brief instant that it takes for the alt to up the current it is providing, the cap gives up some of its charge to fill the void. Another use for a cap is to provide current for transients during very dynamic music where the alt can more than keep up with the average current demand, but the quick transients are a bit too much. The cap can soften the blow to the alt and keep the system going without the alt ever having to provide its maximum current even though the current demanded was for a very brief instant more than the alt could provide. Once the transient is over, the alt provides the extra current above the amp demands to recharge the cap but it never approaches its maximum current production. This is the explanation for the people who installed a cap and it stopped their lights from dimming. Note also that this only works when the transients are very quick (rock music with the quick drum hits, not rap or other such with the long drawn out bass notes). The cap acts as a shock absorber to keep the full demand of the system from reaching the alt all at once. It spreads the demand out over a few seconds and provides some breathing room for the alt.

The thing that most poeple fail to realize is that a cap is not a fix to a problem. It is a slight improvement to a charging system that can already handle the load placed on it. It will not fix anything, but once the real fixes are in place it can help to prolong the life of your alternator and your amps by reducing the duty cycle on both.

 

[helotaxi 5,000+ posts]

So basically a more accurate, more in-depth explanation of what I tried to say //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Basically...

 

[Ricktc 10+ year member]

OK guys, so should I think about investing in a cap? Soon to have an optima Yellow Top, but should i think about a cap to help out with burps while the car is not running?

 

[helotaxi 5,000+ posts]

Ricktc- No. No. And, ummmm, NO!!! Caps are of zero, zilch, nada benefit with the car off.

 

[maylar 10+ year member]

Caps don't "hurt" anything. They are simply storage devices.

A perfect capacitor would add no additional stress to a charging system at all. Whatever energy the cap delivered during discharge would have to be replenished by the alternator, but it's no more energy than the alternator would have to deliver by itself if the cap wasn't there.

Of course there's no such thing as a perfect cap. They have losses, so the recharge energy is always higher than the discharge energy. So it stands to reason that they add additional load to the system.

However... really low ESR caps are very efficient. The benifits of having a high current localized source close to the amplifier could justify the little extra load that they create, under certain conditions.

It really depends on the music you listen to. If your music has bass notes that last long enough to discharge the cap (down to battery level, as helo pointed out), a cap will get you absolutely no benefit.