Saw a discussion on how Trijicon’s eat up CR123 batteries which aren’t cheap. Was looking at a rechargeable solution that will also work in cold weather, like -15 below type weather. Saw some use 16650 (I think) batteries, if one used 18650 batteries that’d be great as I already have a bunch of those. Also read that some well known solutions don’t work well in the cold, so want to make sure this will work in the cold and is affordable.

So, what is the best “cold-weather” rechargeable add on battery for Trijicon Hunter MK Thermal Scope?

Anyone?

Most people do not recommend 18650 because they may not have a constant voltage when fully charged. Have you considered the battery system from Ultimate Night Vision. I have used one since they first started making them with no complaints. It's kinda cool that you get to decide what capacity you need, which basically dictates the battery size. Bigger battery packs run longer.

Same here, external battery pack from UNV. Used it in weather down in the teens, that's as cold as it gets here, with no issues. Supposed to last for around 20 hours, I've had it on for about 9 personally and still had two of the four reference lights on when i plugged in to recharge. Reap IR is what is use it on.

There you go. IR-X Kit, although you may still feel ripped off by the pricing :)