Today my third alternator died. First one died of being old. But two others, i don't know. They both died week after installation and both started with jumping voltage 11.5V-14.5V. It was like that for a day or two and after that voltage stayed at 11.5V with non working alternator. What might be a reason of those alternators dying like that??? Any suggestions???

 

Are you buying new, remanufactured, used, and from where ? Are you sure they are 'dead' and the belt is just not slipping ?

 

They are used (remanufactured) I guess. And belt is not slipping.

 

Are you feeding them?

 

could be your battery. are you running any big watt stereo amps?

 

excessive draw, or high amperage. Check your grounds, and if you have a big stereo, unhook it.

 

Where are you buying them? And most likely the regulator is the only thing going out, usually a problem with quality. Autozone alts have always been garbage to me but NAPA is OK.