Battery light just came on. If the battery isn't charging because of a bad alternator, how long can I drive on just battery power?
My car has 175000 miles.
My car has an automatic transmission.
This may be a sign of a weak battery, a failing voltage regulator or failing alternator. As you may know, the alternator is responsible for charging the battery while the engine runs by generating amperage and recharging the battery while the engine turns the alternator. The voltage regulator is a unit that regulates the charging of the battery by the alternator and maintaining a certain amperage while the engine runs. When the alternator is not working properly, this may result in the battery quickly losing charge. If this is in fact a faulty alternator, you will not have much time to drive on battery power alone. You may expect to drive for anywhere between 15 minutes to an hour on battery alone. Beyond this, your battery will eventually fail and your car will shut down. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your charging system.
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