WRK, I fly 20 pound planes with a 50cc engine and use a four cell NiCad battery pack. I fly in circles at full power most of the time. The consumption per hour is 600mah. It a number you can calculate for yourself for your particular set up and flying habits. 800mah for “a flight” sounds like a lot. Assuming that you flew for 10 minutes, that is 4800mah per hour or an average consumption of 4800ma. I would advise you to do some recalculation in accordance with the way I or Truck recommended. Dan.