One year in the glovebox for an 18650 li-on battery

I’ve seen arguments online about whether keeping an 18650 battery in your car is a good idea or not. I always remind people giant banks of 18650’s power Tesla’s, laptops, and power tools, all of which see all kinds of use and abuse in all kinds of climates.  Still, I have seen people insist that the wide temperature ranges will somehow kill an 18650.  Well, a year ago I decided to toss one of my 18650 powered flashlights in my glovebox to see how it would fare. I used it on occasion over the last year and did not charge it at all. I pulled out my multimeter and checked it last night and would you look at that…

Sitting at 4.05 volts. Like I said, I have used this flashlight a handful of times, so this is basically still a full charge. A full charge would only be about 4.1 volts anyway, so the small drop is just from my use of it. Tested and verified, I have no qualms about leaving an 18650 powered light in my glovebox for years to come.