How Hot Is Too Hot, In A Car? Lithium Ion Rechargeable

Orion

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I'm sure it's been discussed long ago, but how hot it "too hot", to have a flashlight in your car that uses a Lithium Ion Rechargeable cell?
 

letschat7

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Here is my thoughts, tradesmen all the time have powertool batteries in their work trucks that sit out in the sun and you never hear about anything bad happening unless it is too cold and the batteries don't work.
 

yellow

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Touching any surface that feels very hot, or is starting to give burns, it has to be hotter than ~ 65 deg. C.
Even when left in the bare sun, most of the time nothing will get this hot.
Inside a car will Always be less hot than open in the sun
+ 65 C is not good, but also no problem for a battery
 

tex.proud

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Mar 31, 2016
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Texas
Orbtronic, where I buy a bunch of my batteries from has a safety list that includes...

  • Never charge, or store the batteries inside your car in extreme temperature. Extreme temperatures (low or high) might ignite the battery, and cause a fire.
But it does not list what those temperatures are. I'd like to know this as well.

Safety Rules
 

alpg88

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It gets hotter in a car on a sunny day then outside, when my car sits in a sun, when i open the door and get in, I instantly sweat profusely, steering wheel is too hot to touch. After being parked in a sun on a 90f day for few hours temp inside a car can easily get to 140. the coolest place in a hot car is a bottom door pocket. I had one dashcam battery swell up a bit, but other devices, with li ions did not suffer any damage. I had 3d printed items printed with PLA melt like candle wax. manufacturers for li ion say 60c is as hot as you can expose it to.
 

KITROBASKIN

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Doesn't batteryuniversity have data on this?

What I remember is the higher the temperature, the faster the degradation. I have a work pack that I take inside to avoid temperature extremes. Others just buy a new battery when one fails from heat or whatever.
 

Orion

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I use a windshield screen and have Weathertech side window vents, so crack each four of my side windows an inch each. I would suppose that would keep my car from reaching that 60c temp, except for the hottest of summer days. I can bring in the flashlight, in those cases.

Interesting comments so far. Thanks, guys!
 

the_real_chud

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Dec 24, 2023
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Oregon
Orbtronic, where I buy a bunch of my batteries from has a safety list that includes...

  • Never charge, or store the batteries inside your car in extreme temperature. Extreme temperatures (low or high) might ignite the battery, and cause a fire.
But it does not list what those temperatures are. I'd like to know this as well.

Safety Rules
I have an olight Raider + that I have an Orbtronic 16650 battery in. it has been in my car door for 2 years now. Temps from -20 to 110. Both extremes fairly short duration but 20s to 90s are normal. I checked it last week and it still works fine. i've purchased some rc123 lithiums I am planning to put in it this summer but I can't help feeling the issue IN THIS PARTICULAR USE is overblown.
 

NiOOH

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Oct 14, 2006
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Dark-colored cars parked in the sun for longer periods of time, during summer can get hotter than 70 C. I wouldn't leave a Li-based cells in such environment.
 

Monocrom

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If it's going to be stored in a vehicle, and used infrequently, just use a light with cr123 primaries
That's definitely the best option.
I keep an older Fenix PD35 Tac. model in the trunk of my car with 2xCR123 lithium primaries ready to go, just in case.
 

aznsx

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Phoenix, AZ USA
That's definitely the best option.
I keep an older Fenix PD35 Tac. model in the trunk of my car with 2xCR123 lithium primaries ready to go, just in case.
That's my favorite Fenix. With the original one could set to 'tac mode' and effectively no-op the side switch to prevent unintended activation operation. Its replacement did not have that capability as I recall, but was still called 'TAC'. That, ladies and gentlemen is engineering from the Twilight Zone.
 
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TPA

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Aug 26, 2005
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Florida
150+F is what the inside of my car can get to in the summer here. Not sure what the + is as that's as far as the thermometer would read. Is it good for the batteries? Probably not, but no issues thus far.
 
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