Customer brought in today a DieHard Gold (3 yr. warranty) 86-2 battery (1/2020 mfg. date on battery) that he said was bad. Could not find customer's purchase record in database. He had no receipt, and he could not recall which AAP store battery was purchased at (not unusual at all). Battery tester indicated that battery test cables were reversed when we tried to test battery. Checked battery with a multimeter and found that the battery polarity was reversed. The positive post was negative and the negative post was positive according to my $7 Harbor freight digital multimeter. Battery voltage on battery was approx. -12.62 VDC, which is pretty normal (except reversed) for a fully charged 12VDC flooded cell type battery. Could this battery have been completely discharged during ownership due to whatever reason , and then had a charger placed on it by customer/owner with the charger leads hooked up reversed? I have never run into this before. Battery checked good with our battery tester with the tester leads reversed. We ended up defecting the battery and giving customer a new one. I just can't see how a battery was likely in service (date code 1/2020) for a little over two years and then all of a sudden changed polarity. In my several years as a part time AAP employee I have learned that sometimes the customer does not tell the whole story up front. Could this possibly be the case here?
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