93 Sentra charging issues

I did a search on this and came up with mixed problems and solutions. Ok, this started about 6 months ago, while driving around for a while then coming to a stop, the brake/charge light would come on and there was a buzzing coming from the fuse panel area. It was fine until recently when it started happening again. I changed out the alternator and everything was good until a few days ago, when driving with the a/c, defroster and lights on the charge light comes on very dim but when I take my foot off the accelerator pedal it goes off. It seems the fast I accelerate, the more it comes on. Could this alternator be bad also? I cleaned the grounds on the battery cables but didn't seem to help. I got the rebuilt alternator from pep boys, are these crappy?

Thanks!

yeah...i would check the alternator.

put a voltmeter on the battery terminals when the car is running. you should have somewhere between 13.5ish to 15ish volts normally. rev the motor up to around 2500ish and check it again, and voltage should stay somewhat consistent. any voltage climb or drop of more than about .5 volts when you rev the motor is unacceptable and indicates bad voltage regulator. which is part of the alternator.