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Q: Will they test the alternator to make sure it needs to be replaced?

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The battery light came on, yet no issues with power, etc. I stopped to call triple A, because I have a new high amp battery and didn't know if the alternator has stopped charging it. After I had let the car sit for about 15 minutes, the battery light went off. I drove about 25 miles and the battery warning light came back on. There looks like corrosion on the outside of the alternator, and triple A tested the system, as well as running a diagnostic computer test, and everything looked fine. Of course the battery light wasn't on when it was checked. As I said, there were no power issues for the 25 miles I drove with the warning light on, but it has a new strong cranking amps battery...

My car has 145000 miles.
My car has an automatic transmission.

Hi There, It sounds like you may potentially have a faulty voltage regulator or 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. 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. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

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