Using the Phantom 2's battery as reference (5100mah), how does one calculate the power drain IN MaH from a FPV transmitter? Mine is 600mw, so how do I figure this out? I'm probably wrong about this, but at 600mw, is that 600/60 = drain per minute = 10mw per minute. 10mw per minute x appx. 20 minute flight time = 200mah. Is this right?