For me, I just use my voltmeter with a resistor on it and call it a day when the voltage gets down to 4.9 under a good load, the think the resister I am using now draws more than 500 ma. I used to call it quites at 5 volts, but with a higher resistance.

And I agree, the most important thing is to cycle TX and RX down, then a full days charge before flying again. I found plans for a battery cycler online and built one, but I should get off my wallet and buy one with some features it would be nice to know how long the battery lasted before it cycled with out having to watch it.

Calvi