On Monday, May 6, 2013 3:31:41 PM UTC-4, Steve Leonard wrote:
I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14 volt pack for one of my sailplanes. I had one of the batteries go bad, so I did a little checking to see which one. All showed appropriate charge voltage when not loaded, however, one battery went from 6.2 volts no load, to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav. Now, I have seen an individual battery go to very nearly zero volts, but never negative voltage! Turn everything off, and it slowly recovers back to showing about 6.2 volts no load.


Flip the meter around and you can measure the voltage drop of that battery which is now just a big resistor