You didn't say how big your pack was.... but a new battery pack is cheap insurance. Get at least a 1000 mAh pack this time, you'll notice a difference. You may have to upgrade your charger, but the extra capacity is a good thing.

I've got voltwatches in two planes, and they seem to be spot on.

What kind of charger was the pack left on? The regular wall wort that came with the radio?

Andy