I check my battery level after each flight. I started doing this when a battery went bad in my 4*60. I had done pre-flight range check, fueled the plane, and then sat and b.s'd for a while. For some reason, I forgot I had checked the battery and did it again. It registered 3.4 volts. Saved a plane with that one. Better 3-4 flights than 6 1/2.