Originally Posted by nitrodude
Just get a new one, they do need to be replaced once in a while. I try to get a new one every year, they are cheap compared to the cost of fixing a runaway car and blown $600 motor. I charge mine at .5A, otherwise you just hurt the pack, unless I need to charge at the track and Im in a hurry, then maybe 1.0A. Get a good charger, thats a must.
I'd say you've dropped a cell.. to check you have to unpack/unwrap the battery, use a simple multimeter to check across each cell's + and - and if one is considerably lower, you've found the problem.
Max Voltage in a NiMh cell, is relative to it's current (amp) capacity. If all the batteries are of equal voltage, and for each cell < 1.3ish Volts then you need to revise your charging method as the battery is still flat.
Alternately you could have a short in your wiring that's drawing current and likely to let the "smoke escape" checkout the insulation...
Final note, it's a lot easier to "spell it out than it is to do.. nitrodude's option is good advice.
Runaway's are evil!