ORIGINAL: MinnFlyer
The problem with using an unbalanced charger is that the cells do not discharge at the same rate. A balanced charger will charge them evenly so that all of the cells are equal.
With an unbalanced charger, if one cell has more voltage than the other two, the charger can overcharge that cell and... Flame ON!
My charger from hobbycity balances the cells as it charges them, it has a display where you can watch each cells voltage. I is always within .01V of each other. The charger was only $37.