I recently had my alternator rebuilt and my gen light is always on. I checked the volts at the battery while the car was running and it is reading 12.5. My volts gauge in the car is ready just below 12. Is my alternator bad? Any ideas?

thanks.

Sounds like a bad regulator. This happened on my 69, I replaced the external regulator and the light went off.

Do you have an internally regulated or externally regulated altenator. If you have an external then that is probably the culprit. First check if it is wired correctly then if that doesn't check out I would replace it. If it is internally regulated then the external voltage regulator needs to be rewired to allow for the internally regulated alternator. Hope this help let me know if you need more info.

I have the one wire rebuilt alternator, and needs to be turning a minimum 1500RPM to be charging.

Does your altenator need to be rotating at that RPM because there is a Zener Diode inside that limits the voltage until it reaches 14.2?

I believe the alternator is interal regulated because when we bought the car it was wired to bypass regulator. I have checked the wiring to the alternator with the wiring diagram I found on this site and everything looks good.

I will take a drive today and see if the light turns off at higher RPM's. I will let you know. Thanks.

ok, the post on the ground post on the back of the alternator is loose. It is a 10SI... so anybody know if you can tighten this?

Thanks.

Your answer is in your other post. :)