High temp effects on batteries?

Apologies if this a dumb question, but does anyone know the impact of high temperature on CR123a's and 18650s? I keep a couple of Surefire lights in my car and extra batteries, but I'm curious what impact hot car temps have on the life of those batteries. Thanks!

Probably not great for battery life. I periodically run mine on my battery tester. I forget the make of it... little yellow unit that cycles the battery to check it. CR123s tend to act full up until they abruptly zonk out.

Just keep them out of direct sunlight and they should be fine. I have been keeping lights in my cars for years and never noticed an issue.

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Thanks guys. Just for science and my own amusement I’ve got a couple of CR123s I’m going to let bake and see how they do for awhile.

Found a previous thread from 2014.

https://www.m4carbine.net/showthread...R123-batteries

Also found some info from a Duracell Safety Data Sheet that a safe storage temperature for CR123A batteries was -4 to 140 degrees Fahrenheit or -20 to 60 degrees Celsius for the metric orientated consumer.

I've a little experience using CR123A's in lots of environments. IMO cold affects them the most. Heat doesn't seem to bother them.