Chuck,

What kind of batteries are these? By any chance are they NiMH? In my experience NiMH cells are not well suited to the high current drain applications in RC Helis. I had a similar experience> Overheating was the problem. When you said you had thought you had enough juice left and couldn't get it offf the floor I suspect the batteries had overheated. No matter how long you leave them on the charger it won't help. My advice switch to LIPOs.

Good Luck,

Nate