Gotcha , Your probably out longer at a time then me also is y I don't have that issue, but -22 isn't it great? ! Hit -25 here other day and winter hasn't even kicked in yetWhen I work outside in -30 C (-22 F) and colder and everyday during break time when I actually use my phone, it reboots instantly as soon as I try doing anything. When it turns back on it has around -20% battery. If I let it warm back up it will raise 3-8%.
Sorry for off-topicness.
http://xdaforums.com/showthread.php?t=2515593