also look at the servo you are running. when i fly my alpa the 900 or 1100 (which evercame with it) i could fly all day with st 47 standerd servos. that pack would last 1 flight with my funtana digital servo's. digs's need more power. i all use a volt watch but it most just for back up every 2 or 3 flight i rechage a 2500 6 volt just peace of mind ( i would hate to lose my plane becuse of some as dumd as not chargeing the pack)