My battery charger can't seem to keep up with me anymore... it was good for about a week, but now I'll constantly have a dead battery before the other one's ready to go. Anyone else having this problem? I suppose I could buy more batteries and have a couple charging at a time, but that would take a few days to start doing, as I'd have to wait for them to get here... also, is it a bad idea to leave the battery in the charger even after its full, like say overnight?