-JB-

This question is for anyone who has done a battery relocate or actually knows what they are talking about.

I would like to hear from Fabrik8

The car is a 93 s13. I am relocating the battery do to my boost pipes for the SR20.

I have the battery box. A couple 150-200amp fuses and I have (I believe) 4 gauge AWG wire laying in the shop. Maybe 2 gauge and I know 2 gauge comes with most battery kits so if I have that then I am good.

But I am leaning towards that I have 4 gauge wire. If I do is this wire large enough to work with out any problems. I am doing everything correctly because I don't want to catch the car on fire. I am running two fuses which is over kill but I'd rather be safe. One fuse will be in the engine bay and one in the trunk. 6-12 inches away from the connection.

I've seen people run 4 gauge.

Fabrik8

4 gauge should be fine. The reason that larger gauge is sometimes used is because the wire length is longer, or the engine is larger and needs more starter current. Really the issue here is the length of the wire. The smaller the wire, the greater the resistance per foot that it will have for a given current passed through it, so a 4 gauge wire will have a greater resistance than a 2 gauge, etc., for any given amount of current. This only becomes a problem when the wire is long enough and the current is great enough that the resistance per foot interferes with the wire's ability to conduct enough current for the job.
You wouldn't want to continuously run starter current through 4 gauge, but the resistance is low enough that you won't build up sufficient heat in the wire to cause a problem, and you should have any problems passing enough current to start the engine. If you can do a clean, point-to-point wiring job without much extra length, 4 gauge should be fine. If you want to err on the side of caution, 2 gauge will be fine too.

Honestly, I'd try 4 gauge, and if that doesn't work to your liking, replace it with 2 gauge. 2 gauge will work in pretty much all instances, but it's overkill in many situations and I'd much rather run 4 gauge than 2 gauge because of the size difference.

Do you have proper wire, or is this car audio cable with clear insulation or some bullshit like that?

-JB-

It's actually 4 gauge awg thin strain tsunami wire. I pulled from a car that had a audio system in that we got in at the dealership.

I have over 12ft so this is my first option. We have a tractor trailer repair shop in Harrisonburg that a friend says sells thick wire like what I need.

Lowes has 2gauge thick strain wire but is used for wiring houses, so I did not get that.

I figure the more strains in the wire the better off it would in passing the current.

Fabrik8

Fine strand wire works well, and is nice to run because it's supple. I wouldn't use car audio wire though; the insulation isn't very durable or chemical resistant usually. It's expensive for what it is, meant to look pretty, and has thicker than necessary insulation to protect against poor installation.
I'd get some real battery cable or welding cable, which is meant to perform under the conditions that you need..

burnoutboy

I used 2ga. An interesting side effect is the wire holds enough power to keep my stereo on for like 2-3 seconds after the car is shut off LOL.

-JB-

Yeah I went to the local NAPA store and they had battery cable by the foot. For $4/ft I didn't think was a bad deal. So I got 12ft of their cable. It's 2 gauges and I think it's the better choice. I think the 4 gauge I have would work but like you said I was questionable on the insulation. It's really not very strong. Do it right and once the first time so why not spend the extra money on it.

Thanks for the help.

+rep

edit: I already rep'd you one once so if I could I would do it again.

Fabrik8

That's nothing to do with the power wire. That's not how electricity works. There isn't anywhere near enough capacitance in that amount of wire to supply enough current to keep the radio on for a measurable amount of time. If you have amps in your system, they have fairly large bulk storage capacitors on board, and can hold the system on for a few seconds after shutoff depending on the way the input turn-on circuitry is designed.

DeFunk

Visit your local marine store, typically they sell some very nice fine strand aluminum coated (for its anti-rust properties) for far cheaper than you'll find power wiring at say an audio shop.

As usual, I concur with Fabrik. 4 Gauge should put you good for ~135 amps, go to 2 gauge if you're feeling frisky which should be good for ~180 amps.

-JB-

Yeah I went to NAPA and order 2 gauge battery cable they supply. It was $4/ft which wasn't bad. It's the cable that is used to make up battery cables and not audio wire. I do have 4gauge audio wire I could use but I'll just save it for whatever I may need it for.

I'm leaning towards 2gauge just to make sure I am covered with the power in the car. Since I will be running other electronics in the car.

CivicRenModelX

How long are you running the wire?