LiFePO4 and 21700 Li-Ion Safe to Store in Vehicles (High Temp)?

mstgkillr

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I currently own five Quark flashlights (2AA), a few EagTacs (1AA) and a Fenix TK41 (8AA), all powered by regular AA eneloops. Knowing that I would use most of these lights at least somewhat regularly, and two of them would remain in vehicles at all times (in hot SW Florida), I opted for eneloops, primarily for safety. So far this has worked well, as I have only had one issue, when the rubber switch cover almost burst while using the flashlight on high. And, this was a light that was stored indoors, not one of the vehicle lights.

I am considering purchasing a MagLite ML150LR (LiFePO4), Nitecore P20iX (21700i Li-Ion) and Fenix LR35R (21700 Li-Ion). Would these flashlights be suitable and safe for vehicle storage during the summer in SW Florida? I know the MagLite has a charging cradle that can be installed in a vehicle, so it may even charge in the hot vehicle. I would only charge the Nitrecore and Fenix indoors while cool via USB-C.

After a garage fire destroyed my house a few years ago, I am very cautious of all batteries, charges, electrical devices, etc...
 

vicv

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Generally it pretty bad for lithium ion batteries to be in a fully charged state at elevated temperature. I would not store one in a hot car.
For that use case you're better off with lithium primaries
 

GAReed

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I have never had any luck with any battery chemistry stored in a car. e-Vehicles/
Aircraft use active cooling systems to keep their Li-Ion's *cool*.
 

NightFire

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Generally, lithium cells shouldn't be stored in a car. However, LiFePO4 is generally considered safe for high temps, most automotive lithium cells are LiFePO4.

LiFePO4 is much more expensive with lower energy density than any other lithium chemistry, but it's also far more heat tolerant, they're generally reserved for automotive use. I have ~25Ah @12.8V worth of LiFePO4 cells in the cab of my truck. I live in TX and the inside of my truck gets well above 120°, they've survived 2 summers without noticeable problems.
 

mstgkillr

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Are single cell Li-ions dangerous to store in a hot vehicle, or just excelerated battery degradation?

Should just continue using 2AA eneloops for vehicle duty since they have been working well? Would that be a better option than the MagLite?
 

vicv

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I use lithium Energizer aa in c adapters in a maglite to leave in a hot or cold car. Or cr123a. With lithium ion, it's not necessarily a safety thing. They degrade like crazy fully charged in high temps. Eneloops while not as bad don't like it either.
If kept in a car, I presume it's an "emergency" light. Just spend the money on lithium primaries. They'll last decades with that abuse
 

weez82

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I'm not as knowledgeable as others on this form but I do agree with using lithium primaries. They are well worth the cost. Definitely the safe option to use for storing a light in a hot car. I've kept a headlamp in my glove box that uses AAA Energizer lithium primaries for years now with zero issue
 

Johns957

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I have a MagLite ML150LR for emergencies. I charge it and my other lights up on June 1st for hurricane season. I test it (them) when I am done. The Maglite is dead in December. So, I do not depend on it. On the other hand. I had a Surefire G2 in my truck with CR123A batteries.
It was there for maybe 8 years without teaching it. Then one night coming home on the causeway I had a flat tire. The G2 worked perfectly and saw me through the tire changing process. This is in central Florida where the inside of my truck reaches 120 degrees. Hope this helps.
 

thermal guy

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All my car flashlights are for stored for months and months in the dead of winter and 90* summer days. I never use anything but primary cells. It's what there meant for. I would never trust anything else in them.
 

Johns957

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All my car flashlights are for stored for months and months in the dead of winter and 90* summer days. I never use anything but primary cells. It's what there meant for. I would never trust anything else in them.
Yep. For critical applications when I really need my lights to work, I use the CR123A batteries. They never have let me down. Or in the dark.

John
 
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