I took off my battery cables and the positive is much larger in diameter than the negative--probably the way it should be. However, Advance Auto and Napa are showing that the pos and neg cables are both 4 gauge wire. I saw somewhere, I can't remember, where the positive should be 1 gauge wire. Can anyone verify this?

Mike

 

The cables are the same size from the factory. No need for 1 gauge on the positive.

 

I don't know doc, I bought my SE with only 46,000 miles on it back in 1989. I'm sure that these cables are from the factory, and the positive is huge.

Mike

 

The negative should AT LEAST always be the same size as the positive. The same current has to flow through each cable.

 

Listen to the Doc...he's smart! No need for anything bigger than 4 guage for either the positive or negative.

Rich

 

When wire lengths get long is when you need thicker wire. An RX-7 isn't really long enough to justify huge battery cables.

I have some 2/0 I got from a friend. When I relocate my battery I was thinking about using it, but it's really thick.

 

Things to consider include where the battery is located. (longer runs need bigger wire)
Is it auto or stick? (auto pulls about 150 amps - stick pulls about 100 amps when cranking)

You may want to get some good compression fittings.

http://www.taylorvertex.com/hp/index...eryAccessories

Power Cable Calculator

Amp length of run
Draw 4 ft. 7 ft. 10 ft. 13 ft. 16 ft. 19 ft. 22 ft. 28 ft.
20A 14 ga. 12 ga. 12 ga. 10 ga. 10 ga. 8 ga. 8 ga. 8 ga.
35A 12 ga. 10 ga. 8 ga. 8 ga. 6 ga. 6 ga. 6 ga. 4 ga.
50A 10 ga. 8 ga. 8 ga. 6 ga. 4 ga. 4 ga. 4 ga. 4 ga.
65A 8 ga. 8 ga. 6 ga. 4 ga. 4 ga. 4 ga. 4 ga. 2 ga.
85A 6 ga. 6 ga. 4 ga. 4 ga. 2 ga. 2 ga. 2 ga. 0 ga.
105A 6 ga. 6 ga. 4 ga. 2 ga. 2 ga. 2 ga. 2 ga. 0 ga.
125A 4 ga. 4 ga. 4 ga. 2 ga. 0 ga. 0 ga. 0 ga. 0 ga.
150A 2 ga. 2 ga. 2 ga. 0 ga. 0 ga. 0 ga. 0 ga. 00 ga.

The above chart shows wire gauges to be used, if no less than .5 volt drop is accepted. If aluminum wire is used, the next larger gauge should be used to compensate. Cable gauge size calculation takes into account terminal resistance. Wire gauge recommendations based on IASCA guidelines

P. S. I am using #2 ga with battery behind the passenger seat and an auto trans.