I thought my flight times were getting a little short so I checked the charger output, never got over 10.5Volts during a charge cycle.
Next time I tried to charge my battery it just refused to work.
I took a look inside and found the charger was a piece of crap, very poor construction compared to the DF itself. once I untangled the mess on the PCB I found the output transistor was dead (and looking at the thing I don't think I'll bother repairing it)
Next I charged the battery using a current / voltage controlled PSU and it charged up just fine
So it looks like the battery can take the heat but the charger can't. :P