Im almost possitive that i need one but i just wanted some other input. My main question is if i need a 1/2 farad cap or a 1 farad cap. I have an xplod XM-1002HX amp powering 2 ultimate competition 12" subs. Im also planning on adding an undercar neon kit. Im running the stock alternator and a Vortex battery.

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1987 IROC-Z 305 TPI
S/R Torquer heads,Compucam,Edelbrock TES,SLP Runners,52mm TB,Ported plenum & intake,Hypertech Thermomaster chip,plus a bunch of other mods.

 

1 farad for every 1k watts. Keep in mind that a cap will not help you if you alt is undersized.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 3/14/01)

There can be only one!!

 

Well i know i need to go with only a 1/2 farad cap, but will it help me with my headlights dimming and when i get my neons installed?

 

I'm no stereo install expert, but here's my thoughts. Your stereo, lights, computer, ignition, and other misc. electrical components are all hooked up to your power system (battery, alternator) in parallel. If you connect a capacitor to the system, also in parallel, the power stored in the capacitor will become available to the whole system. Therefore, it should have the ability to smooth out power fluctuations. If your headlights are dimming bad, and you are gonna put neon lights (blech) in, then perhaps you should plan for the future and put a slightly larger cap in. It could never hurt.

 

A properly installed cap should not effect the rest of your electrical system. If it did, it's purpose would be defeated.

Now, if you do install the cap in a way where it does effect the entire system, then it may help with your lights, but probably not enough to warrent it.

If I were you, I would upgrade the alternator before installing a cap. If you're going to install neon lights, and you have a powerfull amp, then you need lots of power.

Don't band-aid the system with a cap, fix the problem at the source ---- the alternator.

my 2 cents ........

Thomas.

 

Stoopalinin, that's just plain wrong. Wrong. Here's why. Batteries themselves are considered a form of capacitor. It stores electrical energy as chemical energy, and converts it back into electricity as is needed. Any and all thing hooked up to an electrical system draw from the same power source - your battery, alternator, and if applicable, a capacitor. Capacitors are hooked up in parallel with the rest of the power system. When one component has a load placed upon it, it will affect all the others. That's why your car can't run without both a properly working alternator and battery. It depends on both do deliver a steady, even charge. A capacitor acts as a fast way of compensating for large power draw, i.e. from a heavy bass hit. It will not, however, be helpful if the total system draw is greater than what the charging system can provide. Let's take a 75 amp alternator, for example. The fuel pump, spark system, computer and EFI stuff take up, say 40 amps. That means 30 are left over for lights, stereo, and accessories. Your headlights may use 5 or so amps, and your interior stuff may use another 5. that means 20 are left for stereo. In a stock system, that is often plenty. But if you start putting in amps that will be doing deep, hard bass hits, the current required to power the amps is too great, and thusly each component will recieve less power, all in effort to maintain continuous power delivery. A capacitor will provide a no load battery to store up charge not being used at the moment, and can release it at a millisecond's notice when needed. I'm having trouble explaining myself, but I hope you get the idea.

 

Hey '87 ...... yea, I understand what you are saying. You are completely correct, that's exactly how the battery, alt, and cap work with each other in the configuration you mentioned.

What I said was that a properly installed cap will not effect the rest of the system.
To me, a properly installed cap is one that is isolated from the rest of the system. It just doesn't make sense to install one without isolating it.

This means current is able to pass from the battery/alt to the cap, but is unable to pass back up the circuit towards the battery/alternator.
I don't remember the component used to do this (some sort of relay), but it is pretty common in competition setups.

Thomas.

 

Sorry, Thomas, my bad. I had forgotten to take isolation into account. Thanks for understanding.

 

Hey, no problem man .... that's what we're all hear for, right? To help each other out.

A lot of people install Cap's the way you were thinking, it's real common. When they finally put an isolator in though, they really see the added benefits of what a cap can do for your system!

See ya,

Thomas.

 

Thanks for all the replies. So what amp alternator do u think i should go with? My amp is a 280w. And i already have a good battery.

 

what if u installed 2 caps one for your system and one for your accesories? and u isolated the one for the system, would that help his lights problem?

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87 IROC-z 305 TPI 5spd Borg warner 9-bolt 3.45 posi 4 wheel disc,8.8 Accel wires , bosch platinum +4 plugs,gutted air box,TB coolant bypass ,polyurethane tranny and torque arm mounts, k&n oil filter,synthetic oil 10w30, futura GLS super sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works

 

caps are just for "buffering" your power...they do not make their own power, the only way to get more power out of your system is to just add a larger alternator...

i had 2 1.0 farad caps and 2 900CCA batteries off my 105 AMP alternator, and my lights didnt dim or nothing, but voltage would drop to about 10V's sometimes, i added a 190 Amp cold 220 Hot high performance alternator and my voltage rides fine(ive also taken off the second battery)...so basically, you can only "buffer" your power supply so much before you need the bigger alt to feed it all...

 

The cap will help on the bass amp side because the bass amplifier does not require that much power all the time.
When a low bass hit comes, the amp needs a surge of juice to produce the low, loud frequency -- this is what the cap is for.

A cap will not help with neon lights at all. The neons will require a steady stream of juice, and not just sudden surges.

I suggest you do like KlayBuRn did and get a high perf alternator for this type of setup.

Thomas.

 

neon lights basically use no power - but if your getting a huge draw from the amp (ie massive voltage drop and dimming) they will dimm from lack of voltage no matter what - go get a 1 f. cap off ubid.com i got mine (lightning bolt series) for 35$ - but again you probibly need a better alternator