Q: After driving my car will start no problem, but if it sits fir 8_10 hrs batter is dead. Battery is good,alternator is charging .

asked by on October 05, 2017

My battery is charging while driving,because car will start 4-6 hrs after driving. If it sits overnight battery is dead. New battery,tested good. Took cable of battery while running alternater kept car running. No dimming lights or problems while driving.

My car has 90000 miles.
My car has an automatic transmission.

The first thing is to never disconnect the battery with the engine running or you may damage computer or charging system due to overcharge condition. If your battery is going dead after sitting for longer than 6 hours then you may have a draw on battery from many different causes like stuck on fuel pump relay or interior lights left on. The vehicle will need to be checked for voltage draws from alternator or other electrical component by a mechanic like one from YourMechanic.

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