The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Alternator warm with ignition off 1967 C10

mr.precision · 07-17-2018, 09:41 AM

Took a good regulator off oe of my other trucks and measured the voltage across the battery with the current set-up. At idle I was getting around 17 volts, and at fast idle close to 16.5 volts. Not good.
I then removed the two lines going through the radio suppression condenser, and connected them with an alligator clip.
Charge voltage went down to 15.2 at idle and 14.8 at fast idle. Oddly enough, the regulator "chatters" when coming off fast idle. The maximum voltage across the battery also seems to promote this chatter.
Next step is to try a used alternator from another truck I have and measure the voltage across the battery one more time. And, I still need to go through vette's check list and see if anything else is going on.

I suspect that the condenser was causing the high voltage in the initial test, and probably had been that way for years.

07-17-2018, 09:41 AM	#7
mr.precision Registered User Join Date: Feb 2018 Location: Fountain Hills, AZ Posts: 161	Re: Alternator warm with ignition off 1967 C10 Took a good regulator off oe of my other trucks and measured the voltage across the battery with the current set-up. At idle I was getting around 17 volts, and at fast idle close to 16.5 volts. Not good. I then removed the two lines going through the radio suppression condenser, and connected them with an alligator clip. Charge voltage went down to 15.2 at idle and 14.8 at fast idle. Oddly enough, the regulator "chatters" when coming off fast idle. The maximum voltage across the battery also seems to promote this chatter. Next step is to try a used alternator from another truck I have and measure the voltage across the battery one more time. And, I still need to go through vette's check list and see if anything else is going on. I suspect that the condenser was causing the high voltage in the initial test, and probably had been that way for years.