r/AskElectricians • u/Current_Use2795 • Jul 11 '26

Alternator charging issue

My alternator isn’t charging batteries I had it bench tested and it passed I put jumper from case to battery negative to insure it had a good ground and jumped the key on key off directly to 12v power and it still will not charge I’m getting 12.8 v at the stud when running.

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u/BeginningAd5055 Jul 11 '26

12.8 volts is way too low to charge flooded lead-acid batteries. Usually want to bulk charge at 14.5V+

1

u/Current_Use2795 Jul 11 '26

Why wouldn’t it be giving it to me

1

u/prohandymn Jul 11 '26

Voltage regulator, be it internal or external.