Alternator Power Wire Guage

[LTb1ow]

Currently have some 4guage wire from alternator to battery. (Its in the trunk)

Now, since I have AD-freaking-D, I was looking at what size gauge I should have to carry 200amps (max alternator load).

Using this calculator
http://www.powerstream.com/Wire_Size.htm

I should step up to an almost 1/0 size if I want to minimize voltage drop, but I think I would use a 0 gauge. Would go from a calculated drop of 1.25 to .611, which I think would help across the board.

Only downside I see is addition of weight, thoughts? Comments? Concerns?

[NJSPEEDER]

Going to 1 or 0 gauge will be better and is actually recommended by pretty much everyone and that is what the better relo kits usually come with. You will see less loss, you will see less temp if you get into a heavy cycling situation, and the casing is usually thicker on 0 than 4 so it give the additional safety of resisting chaffing better.

There will be no performance gain, just a better way to achieve the same.

-Tim

[LTb1ow]

Well, my concern is that assuming a full load of 200amp (which I know, is never gonna happen but that's worst case) the alternator will only put 12.81v at the battery. So, its discharging the battery or at very least, maintaining load only. That is with 4awg.

Now, jumping to 1awg gives me 13.41v at the battery, much better. So its charging and maintaining load.

[V]

have you confirmed that much voltage drop at the battery currently? For some reason i can't believe there is that much loss. that would imply the taillights on any car will have a substantial drop as well due to being a thinner wire, therefore more resistance. Yet a voltmeter shows only like .2-.3 volt drop, not 1.5+(edit but thats less current..so nevermind lol). I could be wrong though, but i say just use a volt meter and confirm what you're charging voltage at the rear battery is with the 4 awg. If you do see under 13.2v, then id suggest going to a bigger gauge wire.

[Blackbirdws6]

Go big or go home. Your car needs some weight.

[LTb1ow]

have you confirmed that much voltage drop at the battery currently? For some reason i can't believe there is that much loss. that would imply the taillights on any car will have a substantial drop as well due to being a thinner wire, therefore more resistance. Yet a voltmeter shows only like .2-.3 volt drop, not 1.5+. I could be wrong though, but i say just use a volt meter and confirm what you're charging voltage at the rear battery is with the 4 awg. If you do see under 13.2v, then id suggest going to a bigger gauge wire.

Thats just laws of electricity, so with a 200amp load, and that voltage/length/gauge, tis the calculated drop. Taillights don't draw that heavy :wink:

Is that all the time? No, but I stand to reason that with all electrical load on, with a hot idle, the 4 gauge is allowing a significant voltage drop. The "feed" for the loads is a 1 gauge so might as well have the battery charge "feed" be the same, at least in my twisted mind.

[V]

yea, i actually thought about it then edited my post lol

[LTb1ow]

Well, so far seems its a good idea, so gonna try this mayhem tmmr.

[LTb1ow]

So, finally got some numbers from about the system. Also redid the battery positive stud to shut off switch with a new lug and 1/0 wire. There is also a 1/0 jumper from alternator case to a ground on frame.

Cold Idle: 14.30v @ battery, and 12.89v @ fuse panel
Hot Idle: 13.76v @ battery, and 11.80v @ fuse panel

So, looks like I have an issue with the panel feed/ground. It currently feeds off starter lug with a 8 or 4 gauge wire up to it and a short 10 gauge ground. I will call manufacturer tmmr, but my feeling was the ground is just for relays so power flows via each motor ground not all through that panel ground.

Other than that, looks like factory gauge is stupidly inaccurate and I was worrying over nothing :lol:

[Blackbirdws6]

Not too shabby

[V]

did you check voltage before changing the wires? im curious to see the amount of improvement

[LTb1ow]

did you check voltage before changing the wires? im curious to see the amount of improvement

Negative, thought about it, but that meant working on a hot ass car so decided not to.

The voltage at the panel with fans on etc worries me, that seems rather low.