chris_h — Yes, I'm saying that, from what I've read, the LiIon battery would have to use just half the charge fraction that a comparable NiMH battery could use. Like ken1784, I think the TCH's usable battery range (of 40%) is something like 40 - 80% of full charge. A comparable LiIon's usable range (of 20%) would then be something like 50 - 70% of its full charge.

Stan