Inconclusive alternator testing
 

I pulled the alt and took it to a local shop where it tested out at 14.5V. Guy says the voltage regulator is OK and he is replacing the brushes for $20, so it's back to square one on why the battery seems to be overcharging....
Is there anything else they should be looking for? Battery load tests just fine, holds charge at about 12.7V.
What else makes the tach jumpy?

Regards,

I've read about false positive and false negative testing of the electrical systems before including the alternator and voltage regulator.

Do a "search" and see what comes up.

EDIT:
The shop that rebuilt mine (Southfield, Michigan) had an article on the wall, don't know if this link will tell you anything.

http://www.aeimich.com/

http://forums.pelicanparts.com/porsche-911-technical-forum/348937-voltage-too-high.html#post3392535

Same problem you were having. Have you solved yours?

If so, what was the solution?

Bad points can make a tach jumpy.

The Voltage regulator is the ONLY part that can make the battery getting overcharged!