gauge of wire for Alternator to battery?

[Harry 6674]

Use copper stranded that is designed for automotive use. It's more flexible then equipment wire.

[Tom Goldman]

Be sure to use a fusible link or a maxi fuse on each end when using heavy gauge wire for the alternator. , you dont want to burn the car down if the wire gets pinched !

[68camaroSS]

I did a little research on this last year and ended up using 6 AWG fine stranded tinned marine battery cable boat wire on my 90 amp alternater, bought on ebay for 1.25 a foot.

[2percenter]

Funny thing is that I have been using #10 gauge on this connection for some time now with no problems, but I guess I got lucky with that one.
Could the car have not been getting full amperage to the electric fuel pump and electric cooling fan under full load?
I'm going for #4 or #6 to make sure it's right.

[Mike Pearson]

If you put an ammeter on the wire you could tell what the alternator is actually putting out to the battery. I would say its no where near 140 amps. Size the wire on the actual load. Thats probably why the small wire has been working for you. Just remember the lower the voltage the higher the amperage is. Thats why the starter has such a large cable going to it.

[Jim Wahl]

Originally Posted by Mike Pearson

If you put an ammeter on the wire you could tell what the alternator is actually putting out to the battery. I would say its no where near 140 amps. Size the wire on the actual load. Thats probably why the small wire has been working for you. Just remember the lower the voltage the higher the amperage is. Thats why the starter has such a large cable going to it.

Ahhhhhh......... I never thought of that Mike. Makes perfect sense. Thanks. Jim


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[Ron Gusack]

I embarrassed to say this, but I've run 12 ga for years with no problems. I do intend to beef it up though. I run a fan, fuel pump, water pump, tail lights, Racepak, digital 6A and headlights.

[Run to Rund]

The 100 amp alternators in some stock Mopars about 30 years ago used 6 gauge wire and it wasn't real long--between 3' and 6' I guess. If you will only be using 30 amps, why have a 140 amp alternator? The point of using heavy enough wire is that the alternator can run up to its capacity when needed.

[tim worner]

#4 or 6 welding cable works very well

[magnumv8]

Unless I missed it you do not have to run the alternator charge wire to the rear where the battery is....you already have a battery cable large enough to operate the starter in the car so all you need is a cable of enough capacity to go from the alternator to the junction point of this cable (starter solenoid)...that is why you don't need a real large wire from the alternator to this point (short run)......also the charge signal from the alternator can be very a "dirty" signal (not real clean) and this can cause all kinds of RF in the car if not handled well......

D L Rambo.....