1964 Thunderbird overcharging issue - modification

[Shadrack]

I recently did this conversion - https://www.hotrod.com/articles/install-high-output-ford-3g-alternator-older-fords/

My car is charging the battery...at 15.1-15.3+ volts at idle...that doesn't seem right... Has anyone out there done this on their tbird, or another ford, and can speak to what "normal," voltage is? I always thought 13.3 -14.8 or so normal charing. I suspect the alternator is bad - but I have heard a battery with a bad cell can cause this overcharging condition as well. I am in modified territory here, for all I know 15.3 or so is normal at idle for one of these new alternators - then it kicks down later - but I doubt it.

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[Ward 57]

How is it regulated? Your voltage assumptions are in the correct bracket. I'm no expert on alternators but the old generator regulators were adjustable.

 

[Hadderz]

I would presume that the charging voltage is regulated by the internals of the alternator though, some alternators require external regulators so maybe check what you have. 15 Volts does sound high to me and thought 14.6 was usual when running. The regulator stops voltage surging and keeps it constant so wouldn't think with a duff battery it would rise over its 'pre-settings'!

 

[Hadderz]

How is it regulated? Your voltage assumptions are in the correct bracket. I'm no expert on alternators but the old generator regulators were adjustable.

Most modern alternators have it built-in and not adjustable - just one of those lumps of sealed plastic 🙂

 

[BigClay]

How is it regulated? Your voltage assumptions are in the correct bracket. I'm no expert on alternators but the old generator regulators were adjustable.

If your TBird is stock, I think ‘64 was the first year of the alternator. (Replacing the older generators). There is a mechanical voltage regulator (non-adjustable) on the back side of the radiator core support on the drivers side of the car. ( it is a “box” approximately 2”x 3” in size).
You can purchase replacement regulators from places such as Rock Auto, but most all replacements are electronic, not mechanical. (But that’s ok).