my battery had its polarity reversed?

[ixfd64]

Something really strange happened. I was using a multimeter to check the voltages of some of my batteries, and one of them seemed to have a negative voltage. But when I connected the positive end of the multimeter to the negative end of the battery and vice versa, I got a positive reading again.

Does anyone know why this may have happened?

 

[shadowjk]

The battery ran out of power long before the other batteries did, the other batteries then reverse charged the empty battery, forcing it to go emptier than empty.

 

[Lynx_Arc]

This is why matching batteries is a big deal. It helps prevent one or more batteries from being discharged more than the rest leading to reversal and sometimes leakage also... messy.