167000 miles and finally starting to show a few problems; the latest, the car kept blowing out my low beam headlights. After the second pair I check wires - no problems. Then another day the car seemed to hesitate, the battery light came on, very low power to the car but idling was better than runing the car, even the battery light went off at idling. I tested the battery charge and reading came back above 17 volts! Turned the car off, battery seemed to hold charge, but it blew my headlights again. The shop changed the alternator saying it was way over charging the battery and the higher voltage blew the lights once I turned them on. It ran for 3 days and it did it again, hesitated and battery light back on... again it blew the lights (I was driving at night, the brights worked so I made it home). I charged the battery last night because after a 5 hr shutdown the batterry was dead - but it took almost 4 hrs to charge to 80% and 12 volts... I was afraid to leave it on the charger overnight and blow up. I'm thinking to buy a new battery, as I don't believe the car will start, but what is causing the over charge? could it be a bad alternator to begin with then a damaged battery to finished it off? I dont'want to spend more money on guessing what is wrong! any help is greatly appreciated.

 

The charging from the alternator is controlled by the PCM/ECU. It tells the alternator when and how much to charge. Test the alternator output at the alternator rather than the battery. Should be approx 14v.

 

Also get the battery load tested.