Makes me wonder if anyone designed a say 2xAA battery warming sleeve adaptor for the camelbaks or bladder packs and that unit turns on every 3-5 mins to warm the tube to keep it from freezing. Being a neoprene cover it should hold the heat in and cycling every 3-5 mins would save battery power.

Hmm... I think I just came up with an idea for those that are skilled enough to make it come true it the product is not already out there.