There is another connection for auxillary battery power. The note on the instructions says "For optimum performance, ensure battery voltage is greater than 5 volts, thus, a 4.8 volt battery pack is not recommended". I read that and decided to try it without a second battery. My flight battery is a 4 cell, 4.8v 1700 mah pack. So far, it seems to work fine. I do monitor the voltage, and recharge if it tests below 5 volts. Of course, the voltage is likely lower than 5 volts anyways, at times during flight. It works.....so far.