One correction. The "C" rating is not what the battery can supply, that's the capacity or the mah level of that battery. The C rating is the maximum current in burst form, that that battery should be subjected to. 20C means 20 times the capacity. If it's a 1000 mah battery, which is 1 amp-hour, by the way, this battery, being 20C can put out a 20 amp burst, 20C. Note that of course, because this is 20 amps, and the capacity is 1 amp per hour, well, that battery will last 1/20th of one hour (as compared to 1 amp per hour till depleted), so the "gas tank" will drain much faster.

The amount of burn available is totally dependent on usage. If you have a 20 amp ESC and fly at, sa 10 amps (take off and fly orbits or something that is not demanding), you will get about 1/10 hour of flight time or about 6 minutes maximum. This is, of course, under ideal conditions. If you have a 2000 mah 10C battery (note.. 2 amps times 10C = 20 amps burst), well, you might get 20 minutes.

A lot of other factors come into play, of course because the receiver and servos consume power, and there is a waste factor in the form of heat that reduces the efficiency. Remember, all the power from electric flight comes from one source, that's the battery. As in fuel, or glow powered, there is a lot of wasted efficiency due to heat, friction, and so on, and the same is true for electric, except there is only a limited amount of power and it all comes from the battery pack.

One safety issue that I always pass on.. please... charge your batteries outdoors, not in your home, or in your car/van/truck.. do it in the open away from structures. Thsee batteries can be dangerous if they overheat... like a slow exploding stick of dymamite!!! (exaggeration.. but you get the idea, I'm sure) Be careful!!

CGr