I have a set of 11.1v 5250 lipos and 2 cells in one battery and 1 cell in the other will not hold 4.2 volts. It bounces around at 4.19 and 4.2. I have ran about 4 cycles of balancing the batteries after use and the problem is getting worse. Is there an issue with these batteries? My thunder power lipos have never done this but these have done it and getting worse since day one