mah is how many milli amps the battery can supply in one hour. if you have a 600 mah battery and your average current draw is 1200 ma your battery will last 1/2 hour. That said those digital servos will eat up their share of the battery and I would not expect much more than 2 maybe 3 flights with a 600 mah battery. I don't know what battery packs JR has out but I use 1500 mah 4.8 volt Futaba packs. (that is a Nicad pack, nimh packs have higher capacity in the same size)