I was wondering if it the Alternator light still flashes even if the alternator is still good?? Could a bad battery cause the alternator light to come on? Because I just put in a USED battery today from a friend and its still doing the same thing. The battery wont hold a charge...I had it get tested and the guy said the battery is junk. He said the alternator is fine. But could the battery have been good, but as drove it up there to get it tested, could the Battery have been going bad driving it up there with a bad alternator not charging the battery??

86 Trans Am 4bll 305

 

how old is the battery? if its more then 5 yrs,time to get a new one...just replaced mine cuz it wasnt holding a charge(mine was 5+ y/o)

 

Do you run a bumpin system or with the car off often??? Most time for a few bucks more a marine battery is the better choice. The same thing as a car battery but lots of reserve power so a big 40 footer with twin 455's can jam all day long with fish finder and radar going and still crank them hogs over to head in fo the day.