Lithium battery life.

I got a lithium battery pack for my ski glove. On high it last for 2 hour, 4 hours for medium but on low it only last 3 hours. Why does the battery not working long on high? Does the cold weather affect the batteries from operating at its peaks power. Would it be better if I use some type of extra insulation around the battery pack so the battery would be cold.





thanks for the help.