You may want to try using a UBEC with LiPo packs. I have been using them for a few years now and haven't had any issues. I use 11.1 volt 3S LiPo packs (1320 to 2100 mah packs) regulated to 5 or 6 volts depending on the servos. With the higher voltage you can use smaller packs and they last for 4-5 flights and are still at 50%.

You can also use 2S packs (7.4 volts), but they go faster because of the lower voltage, but still work great.


Jeff