Was out a few months ago and my Eotech and Vortex Sparc decided they did no want to turn on in the cold weather. Went to change batteries yesterday and they both had no issues at 65F. Is this a thing (I'm used to Texas where 32 is "cold" and I had these out in the teens)? Given the current climate (no pun intended) I'd like something that turns on down to 0F not because I'm off fighting in Sibera, but because I often shoot when its that temp.