How big of a capacitor do i need for 2 4000W amps?

Answer 1

whats the amps RMS? not peak.

Answer 2

At least 8 Farads. Four 2 Farads would be better than one 8 Farad.

If your total system power is more than 1000 watts RMS you will need to:

1. Upgrade the alternator to a high output alternator
2. Upgrade to a heavy duty deep cycle battery
3. Upgrade the "Big 3" - that is to replace the power wire between the battery and alternator and the ground strap.

Failure to do this will result in you replacing them anyway as the alternator will eventually fail.

Here is a guide that will calculate what size alternator and power wires you need http://www.datafilehost.com/download.php?file=6d26c621

You'll need Microsft Excel to use it.

See my site for more info http://spkrbox1.spaces.live.com

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In rare and circumstantial cases, a cap actually helps. I can say this with full confidence as I'm running one in my car an have seen a definite change using an oscilloscope to test the theory.

In my case, my electrical system had a 4 volt gain in the whole drop out when a significant bass track was played using a the cap as opposed to not using it.

My specs:

alternator: 75 amps
audio system: 400 watts RMS (total)
cap: 1.5 Farad
current draw of accessories in car: 30 amps (total, everything on except audio system)

Somewhere in these numbers lies the truth to my success, I'm working on a formula to find this. The problem is no two cars are the same as I've added fog lights to my car which changes things from stock. So there can never be an "all-around" method to determine the usefulness of a cap. So the formula I come up with will be just for my car.

I'm also running a few experiments of my own to determine if a cap also increase the life expectancy of the audio equipment as well.

But yes, it's 0.5 Farad for every 500 watts.

Answer 3

ok, caps are NEVER needed. NEVER. a standard car battery = 20.000 farad+/- Anyone who really knows Anything about car audio will tell you the same. Save your cash. You will need major electrical upgrade to run such wattage. ie (2) 300 amp alternators(if you really run 8000Wrms) and this will run you some serious cash. A stock alt will not support anything over 1000wrms regardless of what you drive. You will need at least one extra battery and an isolator for charging, as well as multiple runs of 1ga power and ground. You also need to search and learn about the "Big Three Upgrade" and do it on your ride. Seriously, spend a month in car audio forums before you spend any $$$. here are some good ones. realmofexcursion.com, splbassx.com, sounddomain.com, elitecaraudio.com,. Good luck, and remember, your system is only as capable as the power you can supply it, meaning your battery(s), alternator(s), and wiring must all be top notch, and Capacitors are BUNK!!, NEVER buy one!!!, it will only mask a greater electrical problem, and present an additional load that your ailing alternator must charge. People in competetions NEVER have caps, Pros never have caps, And NOBODY who advises you to use one has hardly begun to scratch the surface of the availiable knowledge of car audio/electrical.

Answer 4

ull need a 5 farad for each amp. that should do it. a farad equals about 1000 watts. so be safe and go with a 5 farad for each amp.

Answer 5

Capacitor??? How about a bat cap. Trust me...you'll need it. Here this will get you started.

http://www.affordable-caraudio.com/xstatic/batcaps.htm

Answer 6

you don't need a capacitor you have biger problems you need a rear battery a high output alternator and 0 gauge wires

1f capacitos only last 0.4 of a second for 600 watts

Answer 7

try your question at www.audioasylum.com