gauge of wire for Alternator to battery?

2percenter · 05-17-2012, 02:32 PM

Okay, so 6 or 8 gauge it is. I was lead to believe that 10 gauge was enough for the field stud from the alternator to the battery. Yes, the battery is in the trunk.

What type of wire is good? crosslink? solid strand?

Harry 6674 · 05-17-2012, 02:49 PM

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

Tom Goldman · 05-17-2012, 08:37 PM

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 · 05-17-2012, 09:03 PM

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 · 05-17-2012, 10:41 PM

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 · 05-18-2012, 08:15 AM

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 · 05-18-2012, 10:46 AM

Quote:

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

.

Run to Rund · 05-20-2012, 08:47 PM

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 · 05-23-2012, 01:02 PM

#4 or 6 welding cable works very well

magnumv8 · 05-23-2012, 09:07 PM

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.....

05-17-2012, 02:49 PM	#2
Harry 6674 Senior Member Join Date: Dec 2006 Posts: 589 Likes: 0 Liked 0 Times in 0 Posts	Re: gauge of wire for Alternator to battery? Use copper stranded that is designed for automotive use. It's more flexible then equipment wire.

05-17-2012, 08:37 PM	#3
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,477 Likes: 892 Liked 883 Times in 237 Posts	Re: gauge of wire for Alternator to battery? 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 ! __________________ Tom Goldman 1500 SG , 1506 STK

05-17-2012, 10:41 PM	#5
2percenter Junior Member Join Date: Apr 2012 Posts: 14 Likes: 0 Liked 0 Times in 0 Posts	Re: gauge of wire for Alternator to battery? 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.

05-20-2012, 08:47 PM	#8
Run to Rund Senior Member Join Date: Sep 2007 Location: Henderson, NV Posts: 583 Likes: 8 Liked 54 Times in 27 Posts	Re: gauge of wire for Alternator to battery? 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.

05-23-2012, 01:02 PM	#9
tim worner Senior Member Join Date: Jan 2002 Location: duncannon Posts: 837 Likes: 14 Liked 126 Times in 20 Posts	Re: gauge of wire for Alternator to battery? #4 or 6 welding cable works very well __________________ Tim Worner SS 1747

05-17-2012, 02:32 PM	#1
2percenter Junior Member Join Date: Apr 2012 Posts: 14 Likes: 0 Liked 0 Times in 0 Posts	Re: gauge of wire for Alternator to battery? Okay, so 6 or 8 gauge it is. I was lead to believe that 10 gauge was enough for the field stud from the alternator to the battery. Yes, the battery is in the trunk. What type of wire is good? crosslink? solid strand?

05-17-2012, 09:03 PM	#4
68camaroSS Junior Member Join Date: Aug 2008 Location: columbia TN Posts: 88 Likes: 0 Liked 0 Times in 0 Posts	Re: gauge of wire for Alternator to battery? 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.

05-18-2012, 08:15 AM	#6
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,452 Likes: 615 Liked 1,937 Times in 582 Posts	Re: gauge of wire for Alternator to battery? 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. __________________ Mike Pearson 2485 SS

05-23-2012, 09:07 PM	#10
magnumv8 Member Join Date: Feb 2009 Location: Coraopolis, Pa. Posts: 172 Likes: 0 Liked 0 Times in 0 Posts	Re: gauge of wire for Alternator to battery? 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.....