This is the first time I've used the larger 5-cell battery for my glider servos instead of the common 4-cell. I'm excited to experience the luxury of increased strength and speed of the higher voltage. I just started wondering, how low should I let the battery drain before I need to stop flying and recharge? At the low voltage of a 5-cell or of a 4-cell? FYI I'm using a NiMH and I don't "need" the extra servo speed and strength. Also there's no motor on the glider.

At 1.1 Volts per cell the battery is pretty well discharged. So at 5.5 volts the pack is dead. Most of us will stop well before that - maybe 5.9 volts.

I actually measure how much energy my planes use per flight, and then use that data to decide how many flights to fly.