(2) batteries negative volts under load only

[LoudLowNslow]

Hey y’all
Checking voltage today, I have (5) batteries reading over 6 volts and (1) reading 3volts.
But with the rear end jack up off the ground and checking batteries under load, (2) of them read negative voltage. And yes, they’re all wired correctly.
How is this possible? I understand reverse polarity, but how only under load?
Thanks for any advise
Paul

[Fairtax4me]

If your meter is hooked up right it's because those two are toast.
The polarity may not actually be reversed, it may just be because of the way the meter shows voltage. With enough load on the batteries it may show as a negative voltage on the meter because they can not produce enough amperage to put out due to very high internal resistance. Or that they are not allowing enough current to pass through them.

The only way I know of for a battery to totally reverse polarity is for it to totally die, and then be charged with the charger leads reversed. (connected to the opposite terminals) Or for a new battery that has just been filled to be charged with the charger leads reversed.