Or 'coat pocket' I wouldnt pay for a lipo warmer when human body heat is free and works just as well. But yeah, warming the lipos to around 90-100*F will yield best results.
I can just see Neil roaming around on a cold winter's day with lipos taped to the inside of his thighs trying to keep them warm...
I too noticed that cold lipos do not perform very well.
Yea heat is a factor on any lithium battery, the heat it produces and the heat around effec the chemical reaction producing more power. If I remember correctly if a data logger with a voltage sensor on it was to be hooked up to the battery and logg the info you'd actually see, say a 3s 11.1v peek at 12.5 or 12.652v just from the extra chemical reaction from the heat....Sorry for hte partial lecture its a habbit.