What gauge wire should I use with a dual battery setup?

[randomguy0o1]

My question is basically this: what does the current look like(not actual LOOK) from the alternator to the first battery? Is it the same as from the second battery and to the amplifier? I want to run two batteries in parallel and try to not have to upgrade my wiring. I have 4 awg wire running from the battery. I don't acutally have a 2nd battery yet. The wire from the alternator is stock. I know that if I have one single battery, the 4 awg would burn up since it would be running the length of the car and be carrying around 150 amps (the fuse on the amplifier is 160a). What should I do? Do I have to upgrade to 0 awg?

Click to read more...

 

[adulbrich 5,000+ posts]

What amplifier and what impedance are you wiring to?

 

[n2audio 5,000+ posts]

4 awg wouldn't burn up at 150A, but the voltage drop would be significant which the amp probably wouldn't like.

Honestly, if you listen to music and not full volume test tones constantly 4 awg is probably fine -- although I expect a lot of people here will try to convince you that running 4 awg in your set up would be worse than beating your kids.

At high volume an amp capable of ~150A peak would draw 50-60A average with bursts over 100A. The alt provides the current until its limit is reached and the batteries would fill in the rest -- the closer the battery to the amp, the more current draw. Assuming your alt is stock and 100A or better the batteries shouldn't be doing THAT much work most of the time.

All things considered - larger wire wouldn't be a bad idea, but I wouldn't be surprised if your 4 awg is perfectly adequate. Your listening habits have a lot to do with it.

However, if you want electrical overhead for a 2nd (full range?) amp you should definitely step up your wire size -- and alternator while you're at it.