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Old March 28th, 2021, 04:09 AM
biscaynebirdie biscaynebirdie is offline
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Join Date: Jan 2021
Location: Santa Rosa, California
Truck: 1965 1000 Series with 250 engine and SM420 transmission
Posts: 26
Rep Power: 27
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Default Re: Overcharging alternator and buzzing voltage regulator

Quote:
Originally Posted by James View Post
Voltage drop is great.

With the engine idling and the headlights on high and blower running, your voltage is doing what it is suppose to do. If you was to raise your rpm the voltage will come back up. Just remember you are normally driving so the engine rpm is higher all the time and the voltage will be where it needs to be. If you have ever seen a amps curve for an alternator you will notice the higher the rpm the more amps output you will have. Proper voltage setting is with everything turn off with a fast idle (approx. 1000 rpm).
I wasn’t aware of this. If the truck just stayed at idle all of the time, I suppose it wouldn’t really be a truck!

I checked the voltages at various RPMs today once I got home from work. This was done with no accessories running. Ambient temperature under the hood was 80F.

Idle: 12.9 volts
1500 RPM: 13.7-13.8 volts
2500 RPM: 14.7-14.8 volts

According to the 1963 Chevrolet Truck Shop Manual, this is right within specification.
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