I have 3 flashlights in my jeep all running on unprotected 18650 cells. I’m wondering if that’s safe with the high heat here in Virginia plus it gets hotter inside the vehicle?
Thanks
I’m sure you’d be able to find a number of people who say it’s ok and store their lights in their vehicles, but the general consensus from reading other threads on BLF is that it’s not the best practice.
There was a recent post with someone with a dark grey BMW, who measured the heat in various locations inside the car. I think the glove box was the coolest location, and top of the dashboard being the hottest.
The coolest place in a car is behind the drivers seat on the floor; the windows must be open about an inch or 2 (air flows from hot to cold; cracking the windows will cause the hot air in the car to rise to the top and go out the crack in the window)
I got the info from a photography course in answer to a question asking where is the best place to keep your camera in your car.
I have a hardtop JK and it gets extremely hot under the sun… I have kept my D4 in the center storage over a year and didn’t see any noticeable performance loss from the VTC6. Maybe not the ideal conditions but I’m sure it can handle ~45° C.
I also keep a 20,000mAh emergency starter powerbank that has Lithium polymer cells inside, if there’s a battery that could go wrong with heat that’d be the one, and it’s holding up fine as well.
man i wish i had the patience to convert to celsius.
tl;dr
I expect to get dogpiled on, but I Just Don’t. I don’t care if cells can in theory withstand X° or what. All it takes is one “whoopsie!” in summer heat and the whole car bursts into flames.
No phones, no cameras, no nuthin’ that has a Li cell inside. If I ain’t there to toss it out a window in a hurry if it starts to go supernova, I ain’t leaving it in the car.
i agree, mr lightbringer
on the other hand, has that ever happened to anyone?
car fire from li battery in summer heat?
( i went to cr123a li primary lights for the car )
Most fires and explosions are from charging a device with a cheap charger and cheap cells inside the car.
Look at electric cars, the floor is full of 18650s and its working fine. Biggest risk for the batteries is a car crash.
Here is Samsung’s test for heating a 30Q cell which it must pass for safety:
Heating test
Test method: To heat up the standard charged cell at heating rate 5℃ per minute up to 130℃ and keep the cell in oven for 1hr.
Criteria: No fire, and no explosion.
So, unless your car is well past the boiling point of water, I wouldn’t worry about it.
Doesn’t even have to be the cell itself that melts at in-car temps. Just a soft-plastic insulator on a wire that goes a little too soft, and things can potentially short out.
I mean, hey, we’re not supposed to put heaters, candles, etc., within 3’ of curtains or upholstery, and we (hopefully) don’t. Not because it’s a definite danger, but because of the 0.0001% chance it might happen. The cost of being minimally inconvenienced vs having all your goodies go up in flames is what tells us not to.
Oh, just ask DBSAR about his possessed driver. Wasn’t the cells at all, yet it went supernova on him.
My rule is to keep them out of the sun. My car has tinted windows which I crack in the summer so I’m really not worried about it getting to hot it damages anything. Now, if you were to leave them out on your dash, the sun can cause problems, especially with lithium-polymer batteries. This is why a lot of dash cameras out there use supercapacitors instead of conventional batteries. With a conventional lithium-polymer battery like you find in many electronics, it’s extremely easy to have swelling issues after too much exposure to the sun.
I keep a USB-rechargeable headlamp in my center console for the classic “changing a tire at night” scenario and I’m really not worried about it dying in the summer at all.
Laptops full of 18650s have lived in cars for summers on end.
Cop cars have them on mounts in full sun.
Some of the oilfield trucks out here have the same sort of setup.
Don’t know if any have had problems.
Laptops tend to have very high quality batteries that are run within “conservative” specs.
I’d worry more about cells inside a bomb-tube, errr flashlight.
Somewhere I have a temp. datalog from inside the central consul of my car. It’s been a few years but I think it maxed out at 135. Not nearly as hot as the inside or dash temp. If I find it, ill chime in again.
All the Best,
Jeff
My car is electric so tons of batteries in the floor. It has a keep-cool setting in which I can opt to use fan only or A/C to keep the cabin from overheating. I just keep it on the fan mode so it never gets above about 105 F. Even so, I use those Energizer lithiums in my car lights. Not sure if those are safer or not, but for me retaining a charge not being used for years at a time is the main priority. Now that I think about it, I wonder if those are the best choice. But whatever, in my car lights I mainly want a battery that will sit for years and still perform if needed. And not blow up. That last one is sort of an unspoken characteristic I want in all my stuff lol.
For God sakes man, where’s your sense of adventure
I expect that those odds are really, really small… and would require a substandard cell (of which most of us here would avoid). If anything, heat will degrade the lifespan of the cell… that’s probably the only real concern. But to be safer, I’d definitely use a hard lock out (e.g. twist tail cap).
It burned up in my last car.
No need to dogpile. It’s a safe default position.
However, based on test data and established precedent, it doesn’t significantly alarm me. I do keep a Convoy S2+ in my, with the battery half charged, but the reduced state of charge is a precaution for longevity, not concern for safety.