OK, a week ago i changed my altenator. I had tested it at work and the output was low, like 1.5-12 volts. I put in an AC Delco a week ago, at which time i noticed my battery tie down was broken. I didnt drive my car this week, so i woundlt mess up the battery. Ok, enough background. Today i finally get the battery tied down properly. When i drove it tonight everything was cool, then sitting at a light my voltmeter droped to the red line below 13. it stayed there untill i drove about 100 feet at which point it jumped back up to around 14 volts(i still think its a little low volt wise). The belt tension if fine, and the belt is in good shape. I realize the altenator could be bad from the factory, but why the drop? oh yeah, my check gauges light flashed on and off a few times tonight too. sorry for the length, and thanks in advance.

 

Do you have an underdrive pulley on the crank??

My car does and in the last two years I have replaced both the alt and bat.

If you have had a bad alternator for a period of time your battery could have been stressed and is not charging up as good. My battery would charge up but if I played the stereo for even 15 min I would need to boost to start the engine.

I would check the grounds and all cable from the battery and the alt.

 

No underdrive pulleys.

Ill double check the conections, but everything has been normal since it droped at the one light. IM going to check my battery tomorrow at work to make sure is still ok. I dont think the alt. was that bad and probably not for to long. Thanks.