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Q: Charging system

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My car battery is less than a year old. When Battery is jumped, all lights come on but car still won't start. Alternator is also less than a year old. Battery? Starter?

My car has 200000 miles.
My car has an automatic transmission.

Hi There, It sounds like you may have a bad voltage regulator that may be causing the alternator to fail to properly charge the battery. 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. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

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