You mustn't freeze a battery. It's best to keep it and charge it indoors when it's very cold. When you use the battery, it heats itself up. At a constant 10A, it will be noticeably warm after a while, but it depends how much cold air it gets blasted with. Many cell-packs have thin rubber foam and GRP sheets over them plus thick heat-shrink covering that will insulate them. Personally, I've never noticed a diffetence in the cold, but I've always had plenty of power and capacity.