repeated alternator issues

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Jun 13, 2026 | 08:32 AM

#16

lshort

Thread Starter

Laughing Gas

Joined: Mar 2002

Posts: 965

Likes: 355

From: Newton Illinois

Quote:

Originally Posted by Christopher2

What is your total current draw with everything turned on?

Also, with a 135-amp alternator, have you calculated whether 6 AWG is sufficient for the charge wire, or should it really be 4 AWG? If the run is only around 4 feet, 6 AWG may be adequate, but wire size depends on both current and length.
I do not have a way to actually measure the total current draw but with the electric fans (37 amp) , AC (20 amp), Ignition (5 amp) headlights (13 amp) so about 75 amp worst case for load plus battery charging after a start up
How long is the actual alternator-to-battery run? I’m guessing somewhere around 4 feet? Knowing the length and your maximum electrical load would help determine if the wiring is sized appropriately.

Technically it should be #4 the reason I used #6 is because that is what Ford used on vehicles with a 3G 130 amp alternator, the calculated voltage voltage drop on 5' of #6 copper at 130 amps would be .32 volts one thing I do plan on changing is moving the yellow A terminal voltage sense wire from being connected to the alternator power output to the directly to the fuse panel inside the truck. This will make the voltage regulator compensate for any system voltage drop in wiring between alternator and fuse panel

I can start the truck, turn all 75 amps worth of accessories on and be at just under 14 volts at idle. then when things get hot enough it will drop off below 12 volts and reving the truck makes no difference.