Q: I replaced the alternator about 6 months ago. Yesterday while idling the battery light popped on and my car quit.

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After replacing the battery and alternator the battery light pops back on after being cranked for a couple mins. The car seems to be running fine however, there seems to be no power with things. The windows are extremely slow and so are the windshield wipers. What could possibly be the problem?

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

This may suggest a failing voltage regulator. 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. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. 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 as in your case. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

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