I can't speak for the main battery pack as I fly glow, but as for servos and such, put the best in there. Weight savings here for servos that don't center, basically makes for a useless airplane. I think most of the electric guys are running the really light LiPo for the receiver pack with a regulator. I know guys running 400mah packs for the receivers. Also, find the best prop setup for your power system. Even a plane near the 5kg limit with today's power systems still have power to spare. One advantage to electric is you weigh the same when you land as when you takeoff..where most glow setups are well over 5kg at takeoff.

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