I just replaced my alternator yesterday. It came out good other than the fact that now the batt light is on in my car only when the car is off but when my car is running the light is off. What I was wondering is what causeing the light to stay on.

 

Do you have access to a volt meter, what's your battery volts with the engine off and with the engine at idle? Hate to say it but you might have a defective alternator even though you just got it. By the way, I assume you changed the alternator due to this very same reason, and did you install a used or new/rebuild alternator?

 

maybe it's your voltage regulator

 

when your car is not running your batt light is SUPPOSED to be on. and off when running.
If I misunderstood you please clarify so that we can solve the problem

 

No freaking way, I can't believe I read his post wrong. Oh well my mistake, drive thru please

 

That's why I get paid the big bucks

 

ok the prob is when my car is off (key is not in the ignition, car is in park, not moving, not running) The batt light in the gague cluster is on. Now when my car is running the batt light is off. Some told me it might be the voltage regulator. Other than that i dont know what could be going on. Also I went to auto zone where they do the free battery and alternator test and both of them turned out good. But i have no idea what could be causeing my light to come on.

 

sounds like a short, could be the VR but that is part of the alt.
Try exchanging the Alt. for a new one and see if it goes away. It should based on the info you have given.