I was looking ahead of having “unified” emergency light for everywhere with the S2+ but then, the issue of heat in the cars reared it’s ugly head.
First question, has anybody done any testing for summer heat inside the car?
If not, I intend to and publish it, but, how to do it is the problem. I do have a 4 channel temperature reader and lots of probes, but have no means of recording maximums.
The idea of sitting inside a 130F plus car to read it has no appeal. Zero. I like to remained in the world of the living.
Ideally, one would take a reading in the glove compartment, door pocket, under the seat and dash top. Obviously the dash top is a stupid place to leave a flashlight, but stupid can never be ruled out because there is always human error.
Soooooo….has anybody done any summer heat tests?
If not, has anyone any good ideas on how to do them?
Any opinion on how much of an issue heat inside cars is?
I used to drive the 318ti, which is a E36 BMW and barely around any longer (they are still used for track days or similar). Last week one of them was parked next to my car.
The temperature should be comparable to other marques and models as well.
Car color will have a huge impact. But, I rented a white car in Arizona and burned my hands on the steering wheel and unlivable inside without 5 minutes of cooling…and waiting outside.
I have a silver car here but rarely see anything above 96F. Still hot but nowhere near Arizona. The dash top is very warm. Touchable but uncomfortable. The interior is livable…but needs opened windows until the ac takes over.
So any real hot state/country would be out of the question for li-ion inside the car.
I have a dashcam with li ion battery and was in direct sun the whole summer. 40 degrees C outside, but in the car was waaay hotter. Probably 60+ degrees.
The battery has inflated but the dashcam still works…
well I have a baseball flashlight with 1 18650 in it that I keep in the car, and still works fine.
But it’s not in direct sun, I keep in behind the seet
I think the question is less about how it it gets and more about how the cell handles the heat. Research what the worst case scenario is and pop some cells in a toaster oven at a safe distance, for science.
If you’re worried, another option is to use lithium primaries in places that are likely to face extreme temperatures.
Use strong magnet to attach it to the car body (outside the car) above the front wheel is easy and quick to access point ant it is considerably less hot.
what does a GPS use for a battery?
it sits right in the sun under the windshield…
( i use CR123A lights for leaving in the car, though they don’t typically have lumens over 100 or so )
not sure what car temps would do, but i also don;t want to find the car burned out, though if that was common, we’d probably heard it before
most likely it just shortens life of the cell, which isn;t easy to test
and cold temps decrease output, though as far as i know they do not permanently damage the things
oh yeah i forgot - main car has li jumper pack
i think they are lith iron phospate though, not li ion, so maybe not as susceptible to heat damage
or maybe just not as likely to blow up…
I've been meaning to re-do my "car light" with LSD NiMh (Eneloop Pros, probably). My car is a Prius, and if that NiMh battery can handle the heat, flashlight cells can, too.
I'm just not sure what light to leave in it. My last car light was a MagLite 2AA LED thingy, and the Duraleaks it came with... well, they leaked.
But yes, I have similar concerns about temperatures for Li-Ion in my car. It can get to 100°F (~38°C, 311K) in the summer and 0°F (~-18°C, 255K) in the winter. I was thinking of a rechargeable Li-Ion light and the car charger, but at those temperatures I don't want to charge the battery. And really, I just don't want to worry. So, NiMh, low self-discharge, no leaks, better temperature range.
IMO, I wouldn’t put 18650 cells in the car unless they were well isolated from the heat and were discharged to 3,2-3,3V.
The lower the storing voltage, the longer it’ll have full capacity when charged after storage, the lower the self discharge, and the healthier it’ll stay.
TLDR: If you want an 18650 light in the car, discharge it down to at least 3,6V and below, and keep it isolated from the heat. Also, use a tailswitch light obviously.
Use a low VF LED and a 4x7135-6x7135 to get maximum runtime if needed.
Aren’t electric cars like loaded with lithium cells? How do they handle the heat? I guess they probably have active cooling while the car is being used or charged, but while its just sitting there do they?
I think Battery University says thermal runaway can happen at 240ºF (115ºC). I was camping one time and had 2 Samsung 18650’s charging in a hot vehicle. 90ºF day windows rolled up. I ran to open the truck and the batteries were way too hot to touch. Used to have a black F150 when I lived in Southern California. Didn’t take long to realize I would never own another black vehicle. Driving through Vegas on a 114º sunny day, the air conditioner wouldn’t even work.
Your lithium ion cells may not leak or explode, but I would think battery life cycles could be significantly reduced. All bets are off with crappy ultrafire cells.
They are actively cooled, but like with Teslas, they are not inside the car, rather, packed in a case on the bottom of the car. Heat rises, and the battery packs are always in the shade.