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Discussion Starter · #1 ·
I've been around GM products for years, but mostly trucks- '73, '78, '84. My 1972 Chevelle has me stumped. No charge from alternator supplied w/ the car. Fine, went to parts store and bought a 55amp version for the Year/Make/Model. Still no charge, a flat 12v at fast idle w/battery charged and then somewhat discharged (11v). Figured I had a bad alternator from stock. Bench tested fine, but grabbed a different unit (bench tested good). Installed it and got 12.5v at high idle. Then my multimeter died. Took the car out and it started fine 3 times in an hour. Ammeter is no help as it was all over the place, from 6 o'clock to 10 o'clock.

Is it possible that this car has an external voltage regulator?

If so, where is the location?

I thought those Delco alternators had internal regulators...

Thank you in advance for your help.
 

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Discussion Starter · #5 ·
So...upon further investigation it seems I have an internally regulated alternator and an external voltage regulator. There is power at the ext. regulator, while I am getting 12.5v out of the alternator.

Doesn't this just cause a conflict in the charging circuit?
 

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A conflict like each regulator wanting to do the job?
I'll bet it does.
Need the correct alternator made for the external regulator.
 
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You need to decide which system, internal or externally regulated, you want to use and go from there.
 
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Let us know how you make out.
 

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Discussion Starter · #12 · (Edited)
I immediately went to work and completed the conversion mentioned here. My charging numbers went from 12.5 to 14.1.

However...the next day my battery was totally discharged. No, I did not leave the lights on or anything else. Strange.
 
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