Possible to charge a dead battery to reverse polarity?

Joined
Dec 10, 2014
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468
Location
Georgialina
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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yes if the battery is totally discharged then charged backwards it will show negative voltage but not work very well.. due to the construction of the battery and the material composition specifically.

Maybe he just wanted a new battery before that one went out of warranty.
 
Yes. A fully discharged lead-acid battery can be reverse-charged, and you'd end up with battery with reversed polarity. It may measure 12.6 volts on a multimeter, but don't expect continued long life from that battery.
 
I had a friend in the 1960s with an Anglia English Ford. While helping him change spark plugs, I noticed the battery was hooked up backwards. But it started the car and ran fine. Mystery to everybody how it got installed backwards, and why nothing seemed to get damaged as a result. I think it had a DC generator, not an alternator.
 
I had a friend in the 1960s with an Anglia English Ford. While helping him change spark plugs, I noticed the battery was hooked up backwards. But it started the car and ran fine. Mystery to everybody how it got installed backwards, and why nothing seemed to get damaged as a result. I think it had a DC generator, not an alternator.
My dad had a couple of old Farmall tractors (Super A and Super C) and they had 6 VDC systems that was positive ground. This system was standard for these 1950's era Farmall tractors from the factory. These tractors were factory equipped with 6 VDC generators .
 
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I had a friend in the 1960s with an Anglia English Ford. While helping him change spark plugs, I noticed the battery was hooked up backwards. But it started the car and ran fine. Mystery to everybody how it got installed backwards, and why nothing seemed to get damaged as a result. I think it had a DC generator, not an alternator.
could,ve been positive ground on those cars
 
My dad had a couple of old Farmall tractors (Super A and Super C) and they had 6 VDC systems that was positive ground. This system was standard for these 1950's era Farmall tractors from the factory. These tractors were factory equipped with 6 VDC generators .
Yes old tractors were positive ground. That has nothing to do with a reversed polarity on a battery. Even with a positive ground, you always observe proper polarity when charging the battery.
He (OP's customer) connected his charger up backwards when he charged it up. Amazing the battery did not explode or fried something. Any warranty should be voided in that situation.
 
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I think it had a DC generator, not an alternator.
Likely the battery was normal but the generator was operating in reverse, thus the car had been inadvertently converted to negative ground. The lights starter and ignition will all operate fine on reverse voltage. You'd only notice if there was a radio, which would burn out instantly and never work again.
 
I had a friend in the 1960s with an Anglia English Ford. While helping him change spark plugs, I noticed the battery was hooked up backwards. But it started the car and ran fine. Mystery to everybody how it got installed backwards, and why nothing seemed to get damaged as a result. I think it had a DC generator, not an alternator.
Many cars and what not were positive ground into the late 40's and later. My 1956 case tractor was positive ground when new
 
I had a friend in the 1960s with an Anglia English Ford. While helping him change spark plugs, I noticed the battery was hooked up backwards. But it started the car and ran fine. Mystery to everybody how it got installed backwards, and why nothing seemed to get damaged as a result. I think it had a DC generator, not an alternator.
Brit cars of that era used a positive ground.
 
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