A C8 in every car. It’s just a good general-purpose flashlight. After that it will vary but there will always be a D- cell “headbanger” very handy; those are currently 2D Maggies. Their light production is a secondary feature Always something “AA” powered in the emergency kit or tool box as well. At least 7 battery-powered lights in the workvan (one cannot have too much light at work) Plus at least 2 EDC lights on my person :sunglasses:
After watching my Buick go up on smoke with my favorite stock C8 in the center console (engine bay fire) I am absolutely certain that LiIon is safe in a car even in the highest heat climates. DBSAR’s ‘torch test’ seems to confirm that. I do expect a shortened lifespan from the cell but that’s a very small price to pay for their high performance.
I went through a couple of Maglites in my truck before settling on an L6. It’s not been often that I’ve actually needed a light in my car (I’ve carried a light in my pocket for years), but having something with some decent firepower and reach will probably come in handy at some point (for instance, in case I see a car slide down a ~100ft. embankment again).
Reviving this topic, especially interested in the viability of lithium batteries in the summer heat of a parked car. It looks like there are mixed opinions about that in this thread and two other similar ones:
I prefer something quite bright (~750 lumens or more) and I don’t even mind blinky modes (preferably hidden) for emergency signaling. There are some 4xAA lights that fit the bill, but for the convenience of keeping it charged it would be ideal if it had integrated USB charging, and I don’t know of any non-lithium battery lights with that feature.
not good, though my testing was not very thorough
I keep a couple of lights in my car year round and tend to check the batteries infrequently.
At the end of last summer I did a check, and the light w LiIon (Mecarmy PT16 w 18350) in it had discharged and the light would not turn on. I cant say for sure if the cause was summer heat or parasitic drain, but I blame the heat.
otoh, the light w Eneloop (Lumintop Tool AAA) in it still worked fine.
I dont know of any lights with built in Eneloop charging
my car kit contains an AA/LiIon light… I loaded it w LiIon at the end of summer, but the backup batteries are AA Ultimate Lithium, and an Eneloop. Its a Skilhunt H150.
the little googling Ive done pointed to LiIon having higher self discharge rates in hot weather… High temps here in sumer are only about 90F, though as you know, its hotter inside the car…
I dont have any google data to suggest that the primary risk is fire… but Im also not in an area w 120F summers… google says 140F is the upper operating limit for LiIon…
I wouldn’t leave a Li-Ion cell in a hot car, especially around here where the summers are brutal.
This is my family’s dash cam: https://www.amazon.com/dp/B08DV51H2X
It has a capacitor battery instead of a Li-Ion cell (even though Amazon says that it has a Li-Ion cell.)
I chose this dash cam partly because of the choice of battery.
Here is a temperature log of the inside of my car on a Texas summer day.
It can get pretty toasty in there. Look how fast the temp drops when I get in the car to head home.
I use a 2xC or D light and change the batts every 2 years.
If I really wanted something to last I’d pick something that used 123s.
All the Best,
Jeff
The center console was the hottest,
The dash glovebox in the middle,
And under the seat was the coolest.
Another run (not shown) the trunk was hotter than these spots.
We’ve had this dash cam about 2 years.
Although Viofo is a budget brand, it’s a well respected brand, and this model is supposed to be able to handle extreme heat quite well.
Always something “AA” powered in the emergency kit or tool box as well. At least 7 battery-powered lights in the workvan (one cannot have too much light at work) 
Plus at least 2 EDC lights on my person :sunglasses:
