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Q: Alternator or Battery?

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Driving home, my windshield wipers seemed sluggish, everything else seemed normal. As I turned into my driveway, my radio and nav system shut off, I got a battery light on my dash. I rev'ed the engine and the battery light went off, the radio and nav turned back on. Moments after I let off the gas my instrument panel flickered and again with the battery light. I was able to again rev my engine and get things to normal again.. only for a moment once I let off the gas same type scenario. I pulled forward into my parking sspot, no power steering at this point. I shut the car off can could not start it again. Does this describe alternator failed, dead battery or something else?

My car has 85000 miles.
My car has an automatic transmission.

Greetings! This definitely sounds like you may have an alternator beginning to fail. As you know, the alternator is responsible for charging the battery. The rate at which this happens is correlated to the engine RPM’s as the alternator turns with the rest of the various engine pulleys. This is why the battery light tends to go away and the accessories all work properly as you rev the engine up. As you let off the gas pedal and engine RPM’s decrease again, the alternator charging rate also slows down. This may also potentially be connected to the voltage regulator failing as well. This is a unit that regulates the rate at which the alternator charges the battery. When this is not working properly, this may result in the alternator either over charging or under charging the battery and not maintaining the proper system voltage. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your charging system.

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