I'm wondering if I'd get a decent flight time using a Canon camera battery - NB-6L, and additionally a neater and much faster replacement time. They are 3.7 volts, 1100 mA/h. I already have a number of these batteries which I use on my camera, plus the charger of course. I get an amazing number of shots before a recharge is necessary. Before experimenting though, I need to know what the third connection is on the battery. The other two are marked + and - but the centre connection is unmarked. The camera uses the centre connection. Can anyone enlighten me please ?