I have had since spring a set of 7, TP 5 cell 2600 batteries. I didn't flyi for a bit and came back and found that I now have 4, 5 cell batteries and 3 that have switched gender to 4 cell Each of these batteries had a cell die. What did I do wrong.? Is is typical for one cell out of a pack to go bad? If I leave a battery that is completed charging, inadvertently left to idle on the charger too long, will it drain back through the output of the charger?
Also, since the battery thinks its 4 cell, can I use it as a 4 cell?