Q: What is draining my car battery?

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Car battery drains after a couple of days battery is new doors trunk everything closed, alternator tested and good. Mechanic tested with meter

My car has 87000 miles.
My car has an automatic transmission.

Hello There, It sounds like you may have some potentially faulty wiring that may be causing a draw on your battery when sitting for long periods of time or potentially a faulty voltage regulator that is not properly regulating the charging of the battery by the alternator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may 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. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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