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Discussion Starter · #1 ·
I am going to be re wiring my car in the next few weeks and was wondering what size wire I should run from the alternator to the battery? The battery is in the back and it is a EFI mustang with a Powermaster 140 amp alternator. I remember seeing 4 awg but that seems large. I also will be running it through the firewall with a pass thru 3/8" lug is that ok? Thanks
 

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You can go on Powermaster's website and they have a chart on recommended wire gauge Vs distance based on alternator output. Click on Tech Help then look for the Charge Wire tab and click on it.

My Dad and I installed one of their 140 amp one-wire units on his street rod (ac, high CFM elec fan, etc) few months back. The wire length was approx 14'. We used #2 gauge as recommended.

Heavier wire on certain components is not a bad thing........
 

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Discussion Starter · #4 ·
I am assuming it is ok to use a thru firewall lug with the alternator wire as you can with the battery + and - correct?
 

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I am assuming it is ok to use a thru firewall lug with the alternator wire as you can with the battery + and - correct?


If it were me, I wouldn't. I'd run the charging wire directly from the alternator to the battery. Less chance of having a voltage / amperage drop.
 

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I used 4ga fine stranded welding cable for mine 2nd time around and now don't have any voltage drop back at the battery. Think I have a 120amp alt. Can't go wrong with 2ga though either.
 

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Me

I use #8, but I also tie mine in at the starter lug with the battery.No sense in running a hot from the battery to the starter and then one from the alternator all the way back to the battery. Just my .02
 

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Ummmmmmmmmmm, is there anything wrong with the Chart stickied at the top of this forum: http://yellowbullet.com/forum/showthread.php?t=47266

After all some knob spent 40 hours making all those calculations, and double checked them. So it is pretty accurate. :) As far as I know it is the most comprehenssive chart available.
 

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Discussion Starter · #14 ·
I use #8, but I also tie mine in at the starter lug with the battery.No sense in running a hot from the battery to the starter and then one from the alternator all the way back to the battery. Just my .02
That is not the proper way to wire the car is it? It can still get power to everything if the kill switch is shut off from the alternator spinning and powering everything. The alternator wire needs to go to the battery or the battery side of the cut off switch I thought.
 

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Discussion Starter · #15 ·
Ummmmmmmmmmm, is there anything wrong with the Chart stickied at the top of this forum: http://yellowbullet.com/forum/showthread.php?t=47266

After all some knob spent 40 hours making all those calculations, and double checked them. So it is pretty accurate. :) As far as I know it is the most comprehenssive chart available.
Nothing wrong with it at all and I use it often. I was just wondering about how many amps I will use in my car being EFI and with electric fans and waterpump. I know the alternator is 140 amp but i dont think it will use all of it but i guess it might. So it is probobly best to wire the alternator for the max output correct?
 

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Discussion Starter · #18 ·
Painless only uses #8 in their high amp relay kit to run from the alt. to the battery. Not saying that's right but you would think they wouldn't take any chances going to small.
And this is the type of thing that confuses me... The poweraster chart says to use #4 or #2 but yet they dont sell any over #6
 

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Discussion Starter · #19 ·
Recommended Charging Cable Gauge Size:
AMPS
Up to 4ft.
4 - 7ft.
7- 10ft.
10- 13ft.
13- 16ft.
16 - 19ft.
19- 22ft.
22- 28ft.
35 - 50
12
12
10
10
10
8
8
8
50 - 65
10
8
8
6
6
6
6
4
65 - 85
10
8
8
6
6
4
4
4
85 - 105
8
8
6
4
4
4
4
2
105 - 125
6
6
4
4
2
2
2
0
125 - 150
6
6
4
2
2
2
2
0
150 - 175
4
4
4
2
2
0
0
0
175 - 200
4
4
2
2
0
0
0
00
Part # 1-24 2 ft., 8 AWG
Part # 1-36 3 ft., 8 AWG
Part # 1-48 4 ft., 8 AWG
Part # 1-60 5 ft., 6 AWG

Common Gauge Sizes:
 
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