Cap or not?

[JimJ 5,000+ posts]

if they didn't help, they wouldn't have been invented...

Read my post.

Caps are vital parts of most every electronic circuit, but that doesn't mean they work well in every application.

Read: http://www.kpsec.freeuk.com/capacit.htm

 

[Partagas 10+ year member]

that is a great site...thanks for posting it

true they don't work well for every application and as far as I can tell they only help in a car when you need between 5 and 15 or so more amps. So in that situation it might be impractical to put in more batteries or a bigger alternator

 

[klassic 10+ year member]

I was about to vote yes until I saw 1500 watts rms. At that level you already have to upgrade everything else anyway. Thats alot of current being pulled even for a cap to help momentarily

 

[klassic 10+ year member]

A cap does not hold just a momentary or split second charge as you have stated. A 5 Farad cap will hold 70 amp-seconds @ 14 volts.

Don’t believe me?

.

Lets say that is true. Wouldn't then the alternator and battery be responsible for charging the cap instantaniously everytime it discharges (at the tune of 70 amperes per second according to you for a 5 farad cap)? How is that any less strain on the battery and alternator? When will the battery and alternator have a chance to rest or less of a load to feed where it wouldn't before? And we are talking about feeding 1500 watts worth of current here (which is draining more than 70 amps continiously). In a system this big seems cap is just another stop for current to pass through on its way to the amps.

From what I understand a cap is only able to discharge slowly (if thats what you are trying to say) when the load dictates it (like when the load is small enough only a small amount of its storage is required). But when the load as much or more than its storage capacity (which a 1500 watt system far exceeds) by nature it discharges nearly instantaniously. Is that not true?

basically I dont know what you mean by "it will hold 70 amps for seconds at 14V". It will hold 70 amps all day if there is no load to dictate it being discharged. If it is discharging the load (demanded by the amps) how can it be "holding" it for seconds" and if that is so how is that helping quick transients which is the whole reason for using a cap?

 

[johnecon2001 5,000+ posts]

Lets say that is true. A cap charges and discharges almost instantaniously would you not agree? Wouldn't then the alternator and battery be responsible for charging the cap instantaniously everytime it discharges (at the tune of 70 amperes per second according to you for a 5 farad cap)? How is that any less strain on the battery and alternator? When will the battery and alternator have a chance to rest or less of a load to feed where it wouldn't before? And we are talking about feeding 1500 watts worth of current here. In a system this big seems cap is just another stop for current to pass through on its way to the amps.

Correct. Why add another element to the mix for the alternator to have to feed power as well.

I started to write a really long explanation about capacitors and the math behind why they work but I realized that even with 1900 posts you will still be a moron when it comes to electrical theory.

You should have finished it to prove your point, because now you still just sound like you did no research whatsoever.

A cap does not hold just a momentary or split second charge as you have stated. A 5 Farad cap will hold 70 amp-seconds @ 14 volts.

70 amp seconds? so how many real seconds is that.. about 1.5-2. and then the Alternator still has to recharge the cap.. which adds strain to the system.

Don’t believe me? Then I encourage you to do the math yourself and look up Coulomb’s law, as you can see it’s not called Partagas law. This is real electrical theory not some made up crap that you spit out of your mouth because your mom told you to say it.

ooooo //content.invisioncic.com/y282845/emoticons/boring.gif.42c69fa49b1e73e6332d62b462a2a4b3.gif

The need for a cap in any car audio system drops when you upgrade alternators and put in multiple batteries, but even a 160 amp alternator might need help (assuming one battery) if you have every electrical thing on in your car (headlamp, A/C, stereo) and capacitors don’t hurt especially when you already own them.

He doesn't already have one, and if the need for a capacitor drops when you have all of those upgrade, then Why did you recommend one?

 

[fatryan 5,000+ posts]

the reason im in question, you all, is cause im unsure if my 160 amp alt and optima YT will be sufficient for the work load. i just today bought some 0 awg wire to (once again) upgrade my BIG 3.

like i said b4, i already own these 2 RF 1 farad caps. im just trying to figure out if i should use them or not.

 

[johnecon2001 5,000+ posts]

with the electrical upgrades you already have.. you wiil not need them.

 

[B_Master_Flash 10+ year member]

A 5 Farad cap will hold 70 amp-seconds @ 14 volts.

correct me if I'm wrong, I dont actually know the math behind it, but I'm guessing thats to dicharge from 14v all the way to 0v, which makes that a useless number. How about to discharge from th highest voltage it will see, about 13.8v, to the lowest voltage it will see, about 12.5v.