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Q: Alternator

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The battery light came on so i took the van to a mechanics he did a battery test and showed me that the numbers when the a/c and lights and rear defogger is on they read 13.5 and then went down to12and back to13 and so on do i need to get a new alternator now or can i wait
My car has an automatic transmission.

If your alternator is putting out low charging voltage, that is something that should be addressed sooner rather than later. If the charging system fails completely it can leave you stranded wherever it decides to break down. That said, I would make sure that the battery and cables are in good condition as well, and are not affecting the charging voltage. The battery needs to be fully charged and in good condition, and the cables need to be clean and in good shape, with no excessive voltage drop. A qualified technician, such as one from YourMechanic, can diagnose your battery issue for you and suggest the appropriate repair.

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