Restoring - General discussions that span across many different groups of years and models > Misc Items

Alternator Not Charging

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Mark69Sportsroof:
Hi Everyone,

The next saga on the 68 Mercury is all the lights now work.  The alternator will not charge.  It's showing 12.3 volts idling or when giving it gas.  I have the old original wiring in fair shape at best.  I have a new voltage regulator, starter relay, battery, battery cables, distributor, coil.  I have cleaned and grounds and still no change.  The dash has a light for alternator not charging.

Any thoughts or ideas would be appreciated.  Thanks Mark

mtinkham:
You can take the alternator to your local auto parts store and they can perform a bench test. Process of elimination...

Mark69Sportsroof:
Thanks for the suggestion.  The one that was on the car showed the same alternator reading as the one I just put on.  I took that one off my Mach 1 and it was charging just fine.  I can get it tested.  Thanks Mark

Mark69Sportsroof:
Update.  I took the used alternator and it came back bad.  So I purchased a new one from NAPA and installed it.  No change.  The dash light "Amps" stays on.  So I have  reman battery and took that in to have test.  It came back "battery good" under no load and load tests.

With the old alternator the readings were from 12.1v to 12.3v idling or higher idle.  With the new alternator  showed 12.5v - 12.7v.  So a slight improvement but not where it needs to be.

Any suggestions.  Thanks Mark       

jwc66k:
Replace the regulator. A correctly functioning alternator at 2000 rpm will put out between 13 and 15 volts. Above 2000 rpm should be the same. At idle, you were probably reading the battery voltage.
Jim

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