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Q: Changed out the alternator and battery. Car will not start without a jump.

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Changed alternator, and battery and will not start without a Jump What will cause the battery not to charged back up. the car was driven 3,2 miles and was cut off for 20 minutes then then would not start back up

My car has 146000 miles.
My car has an automatic transmission.

This may be a sign of a failing voltage regulator. This is a unit that regulates the charging of the battery by the alternator. Often times this will result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery.

In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all.

In either case, I would recommend having an expert from YourMechanic come to your location to diagnose and properly diagnose and test your vehicle’s charging system.

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