Battery overcharge

2009 CHEVROLET COBALT
95,000 MILES • 2.2L • 4 CYL • 2WD • AUTOMATIC
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THEABOOT@HOTMAIL.COM
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I recently changed my alternator. But the battery light still comes on and off occasionally while driving. I tested the volts at the battery and they range 14 to 19.
Dec 14, 2019 at 3:17 PM
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ASEMASTER6371
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Good evening,

The range should be from 14 to 14.5. Anything above that is a problem.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

As far as the alternator, did you use a new or used unit?

From the sounds of it, it looks like the PCM may be at fault as that is what controls the charge rate.

Roy
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Dec 14, 2019 at 3:59 PM
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THEABOOT@HOTMAIL.COM
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It is a used alternator but have gone through multiple. From what I was able to gather on the line I figured it might be the PCM. Thank you for your response.
Dec 14, 2019 at 4:37 PM
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ASEMASTER6371
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I would also use a rebuilt unit. Used units may be bad.

You are welcome.

Always glad to help.

Roy
Dec 14, 2019 at 4:42 PM