For an emergency use or little use which type of battery should i use?

jon_slider · May 22, 2020, 10:25pm

missGoogle told me primary lithium has a bit wider temperature range than eneloop:

The Energizer® Ultimate Lithium™
(–40ºF to 140ºF).

Eneloop
(–20ºF to 120ºF).

I believe cars can get hotter than 120F… depending…

but yes, eneloop works fine in my car, in my real world
mild winter temps of 20F
pleasant summer temps of 80F

have never put a thermometer in my car… where my flashlight is… hmmm more corona time entertainment…

you made me look… lol

maybe 18650 are not going to blow up in a car:

bfksc:

fengstar:

Hey guys I have a quick question, is a 18650 powered flashlight “safe” to use and leave in a car? I live in California, which is not too hot and not too cold, but I suspect temperatures in the car could exceed 100f on some really hot days. Is this kind of temperature ok for a 18650 battery?

It is perfectly safe to leave a Li-Ion 18650 in a car, hot or cold. It won’t explode or cause issues in that regard.

However, high heat is very bad for Li-Ion cells especially when fully charged, as it reduces recharge capacity even when not used. Since an 18650 is being used in a flashlight, it will be charged to 100% and then stored in the hot car. This is the worst scenario for a full charged Li-Ion cell. Keeping it at normal room temps or even cooler is better for longevity (charging to 40% and then storing in a cool location is the best method). It won’t cause any dangerous issues, but the life of the cell will be greatly reduced when left for weeks or months in a hot car. After just a couple of hot summers with minimal use, the cell will start to show serious capacity loss, which is a waste of such a good battery.

As others have mentioned, a low self-discharge (LSD) rechargeable NiMH cell like Eneloops are fine for a hot/cold car. They will hold a charge for quite a while and no issues with life cycles from the heat.