I can say for certain that an AR will run fine @ -15F ambient.
How does the cold weather effect the batteries on them.
The 1st answer is, it depends. Are you leaving it on all the time or do you have it in standby? Are you running an LRF? Is the LRF on continuous or single-press measurements?
I have to put my scope in standby if I don’t want to leave it on, and remember to turn it back on when/if I need it.
My scanner has a sensor that puts it into standby if it’s not close to my face for a couple seconds.
Good 18650’s will go about 45Min. 26650’s about 2X that when everything is on.
Iray IBP-2’s last about like an 18650.
All of them will fool you if you let them warm up in the vehicle a bit and neglect to swap them out prior to the next sit. It’ll look like they’re back to almost full charge, they’re not when they cool back down.