RE: Voltmeter for A123 cells
I just don't see the point. You can hit these packs at 10 amps if need be and a fully discharged 2300mah pack would be charged in like 10-15 minutes. If you let the battery get to that point you probably would have lost the plane anyway. Best thing is to do what others have said. Get a baseline on per flight usage and leave a nice cushion to be safe.
Marty