I've got 3 2000mah sub c 9.6v packs that I made up and flown about 10 times in my Zagi XS . Today I only got about half the run time and much less power from one pack . I charged the pack at the flying site and near the end of the cycle one cell was a lot hotter then the orthers. Is that a good indication of the bad cell or should I be useing some orther method .