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Q: Alternator not charging battery

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Have put 2alternator on already still not charging battery when turn the key off volts go up go down when turned on was wondering if ignition lock cylinder may cause this problem

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

This may be related to what is called a voltage regulator which is a unit that regulates the charging of the battery by the alternator. When this is not working properly, this may cause the alternator to be over charged or under charged. Its job is to maintain the correct amperage from the alternator to the battery. I would recommend having an expert from YourMechanic come to your location to diagnose your charging system.

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