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Q: How can you tell if your alternator is working properly?

asked by on

I have had to jump the car the last two times I started it.

My car has 90100 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. Usually this is ...

Hi, thanks for writing in. Usually this is identifiable by the charging system gauge in your car, which should typically read, at idle, 13.8 to 14.3 volts with no lights or accessories on (although some may charge at a slightly higher voltage depending on temperature, engine RPM, type of battery, and the battery's state of charge). This may also be caused by the voltage regulator not working properly. This is a unit that regulates the charging amperage to the battery from the alternator. When this is not working properly, this can cause the alternator to over or under charge the battery as well. I would recommend having an expert from YourMechanic come to your home to diagnose and repair your charging system.

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