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Hey fella on my 82 f100 302 I've done put 3 Alternators in this thing and 2 battery neither is the problem but for some reason my Alternator is not sending the charge to my battery the voltage stays at 12.4 i think is say which is for healthy battery but not for Alternator if anyone has any ideas or dealt with the same issues I would appreciate the help
Hey fella on my 82 f100 302 I've done put 3 Alternators in this thing and 2 battery neither is the problem but for some reason my Alternator is not sending the charge to my battery the voltage stays at 12.4 i think is say which is for healthy battery but not for Alternator if anyone has any ideas or dealt with the same issues I would appreciate the help
its time for the 3g upgrade. Dump the external voltage regulator and step up to the internally regulated 3g.
I would replace the battery cables with the correct ones. IMO your connections are junk. That's not helping. I also stayed with the 2G Alt from NAPA. with the improved connections.
Yea new battery cables is 1 of the first to do.
Does the truck have a AMP gauge or a battery light? If light does it light up when you turn on the key?
I see you did the battery & ALT but I am not seeing anything about a regulator does the truck, and I think it does, have you changed that with the ALT?
If you put 12 volts to the field of the ALT if it is good it should put out max volts and you can hear when it does this.
If the regulator / ALT is not getting a signal (12 volts) to the field it will not charge.
Dave ----
Hey fella on my 82 f100 302 I've done put 3 Alternators in this thing and 2 battery neither is the problem but for some reason my Alternator is not sending the charge to my battery the voltage stays at 12.4 i think is say which is for healthy battery but not for Alternator if anyone has any ideas or dealt with the same issues I would appreciate the help
You will need a meter. First thing to check, with the key off engine off, do you have 12v on that large bolt terminal on the back of the alternator? Looking at your wiring at the battery, I am betting not but lets see what you get.
I would replace the battery cables with the correct ones. IMO your connections are junk. That's not helping. I also stayed with the 2G Alt from NAPA. with the improved connections.
He has a battery in it for a GM vehicle. That is why the cables are so weird.
He has a battery in it for a GM vehicle. That is why the cables are so weird.
Oh Dave that end is ok with me but look at the solenoid / starter relay
That looks all wrong to me
Oh I also see a voltage regulator so if that is bad it will not let the ALT charge the battery and can even kill a new ALT and why you should replace them both at the same time.
Dave ----
Last edited by FuzzFace2; Feb 19, 2026 at 05:46 PM.
Is it a simple upgrade like just unplug and plug in or do i got to do some wire work?
It should be a relatively simple altenator swap and a few wiring changes. But it does need to be planned out. Check out garysgaragemahal.com. Look under documents/ upgrades/ 3g for instructions. It has worked out very well for me.
If he does not have any extra load on the electrical system like off road lights, snow plow or crazy sound system I dont see the need for the 3G ALT.
Besidesw he spent the money for a new ALT already and if he full field tests it and it puts out then why not find out why it will not charge the battery?
It could be as easy as replacing the voltage regulator?
K I S S
Dave ----
I was looking back over the OP pictures and is that a G1 ALT with the regulator on the inner fender?
IIRC Max you said in a post that the new plug you got or the 2G ALT comes with an internal regulator?
Dave ----
The battery connections need to be explained. That isn't going anywhere fast IMHO. Looks like regular tapered lead posts screwed to the GM style battery and then the cable ends over those screwed on tapered lead posts. It's just so wrong.
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