I read a comment somewhere about how grossly inefficient the step up regulators are, so I was curious. The 600 mAh 1S was charged yesterday morning, then I used some juice setting up the radio yesterday and this morning dialing in throws and range check, plus one ground run of the engine. Then the test flight this evening, 3:30 long.
So I put the battery on the charger this evening at 1C – it almost immediately showed 4.20V and the charge rate dropped to 0.2A. So I left it and had dinner. When done, the charger had output 60mAh. So the battery accepted some fraction of that to top up the charge, and some fraction of that figure again was the amount actually consumed on the maiden flight.
Therefore.. I don’t think there is a major problem with inefficiency or any worry about Rx battery capacity here.