Very good question John, NiMh will peak at around 10.5v but deplete easily down to 9.9 or 9.8 soon after the charger is unplugged and then some more for the next day's flying. It'll have a good flat overall curve around 9V, which is why I would recommend charging it at Pb (8v lead acid) mode that peaks only at 9.8V. I think 3S LiFe will have an over all slightly higher voltage, I will do some testings on the 3S LiFe as well.

Barry