[markdafedman]

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.

 

[123pugsy]

I believe it does.
Rad support, driver side.

 

[oldcutlass]

Externally regulated alternator 2 wire plug

Internally regulated alternator 2 wire plug

 

[Dean]

I believe it does.
Rad support, driver side.

Yep

 

[markdafedman]

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?

 

[123pugsy]

A conflict like each regulator wanting to do the job?
I'll bet it does.
Need the correct alternator made for the external regulator.

 

[LevonH]

Explained well here.

You can buy these kits to help clean up the wiring if you like.

American Autowire 27555 American Autowire Alternator Conversion Plug Adapters | Summit Racing

Free Shipping - American Autowire Alternator Conversion Plug Adapters with qualifying orders of $99. Shop Alternator Wiring Adapters at Summit Racing.

www.summitracing.com

 

[123pugsy]

Need the correct alternator made for the external regulator.

I stand corrected by the above post.
Easy conversion.

 

[oldcutlass]

You need to decide which system, internal or externally regulated, you want to use and go from there.

 

[markdafedman]

You need to decide which system, internal or externally regulated, you want to use and go from there.

Thank you for all that information. I will probably go with the internally regulated route as I don't care to buy another alternator. Appreciate the comments, links, and the video!

 

[LevonH]

Let us know how you make out.

 

[markdafedman]

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.