I took my car in today to get it looked at, because i was at a stop light, i simply used the power window button to roll down the passenger side window to talk to a friend, and out of no where the battery light comes on. I quickly head to the nearest mechanic, whenever i came to a stop light the car would act as if it were going to die, when i accelerate the battery light goes away. The mechanic told me it was a bad alternator, so i paid about 270 to get a new one installed, drove the car home and everything was fine. I dropped my sister off at work, i winded down the passenger side window to test it, and out of no where the batt light comes on again....anyone know whats the cause? Im gunna call the mechanic i have a 2 year warranty on it, i cant even start the car. ugh!
Yes the mechanic really did replace it, he's a friend of the family, he even showed me the old one,and the new one looks very clean. The coils inside of it are copper in color. the old one was silver and dirty. I hope it was a defected alternator.

Well, does it new one working fine? if so then surely it was.