re: Thermocell

It takes 21700 lithium batteries, so you can just change them if they die. I use 21700s for the EMR10, my headlamp, and my flashlight so i usually have a charger and extra batteries around all the time.
I’ve never come close to running out because I put fresh batteries in before i go anywhere. It says 12 hours and that would seem right to me, maybe a little less if you use the ultrasonic thing and outdoor mode. I don’t use the ultrasonic thing.