We keep 4 cell , C and/ or D battery Mag-Lite flashlights, upgraded with LED build modules ,in out family cars as utility an emergency , nearly indestructible, flashlights. They are kept in the passenger cabin. But they r still subject to both high heat in summer and freezing cold in winter. So my question is, what in ur opinions , are the best batteries to use to survive the temperature swings, not burst their cases from corrosive battery failure and provide long life power to the LED bulb. Modules?

I too am searching for a good way to power the C/D devices (lights for the most part) and really have had bad luck with corrosive battery failure. I've changed out all the AA, AAA and 9 volt stuff with lithium cells and have had very good luck with that.

I lost a several flashlights and a couple of other devices to corrosive battery failure and managed to rescue only one light which prompted my total switch over to the lithium choices. I've considered using rechargeable C/D cells but don't find a lot of choice or good information on that so I'm still "looking" for good ideas.

no one appears to make c & d-cells in 1.5V disposable lithium so you're left with alkaline

consumer reports and other testers indicated there isn't a huge different in better known brands (eveready, duracell, kirkland, amazon basics, etc)

i would buy whatever you prefer having a good long Best-Used-By date.

just don't leave them in a device! it is pretty much guaranteed that some will leak eventually. store them separately in a container that can withstand that sort of leakage (plastic has worked better for me than a steel ammo can).

while NIMH rechargeables are great for daily use, they loose to much energy over time, so might not be the best for longterm storage.

As others have said battery size limits the options to regular alkaline or Nimh rechargeables.

4 C/D cells generate about 6 volts and guess that is what your LED module is rated for, so theoretically possible to power them off 2 CR123a primary batteries in series, but would need spacers to make electrical contact at both ends and stop side to side rattling.

I've divested of everything C and D cell powered for CR123A, AA and (for a few things) AAA. For this reason.

zactly!

Modern NiMH like Eneloops have a lower self discharge and work well.
That being said no matter what battery I use you should pull it out and check and/or replace a couple times a year, end of winter, end of summer for example.

There are adapters that will hold 2-3 AA's in parallel in a C/D sized container, so you get one of those for each battery and fill them.

I have also gone full LSD NiMH AA/AAA for everything and will never go back to equipment-destroying alkalines.

However, I haven't noticed "heavy duty" batteries causing damage like alkalines do. True, they have less energy stored, but the LED modules help to make up for that. Perhaps H/D in the lights, and alkalines stored externally as backup?

If they are "genuine" "heavy duty" they will have carbon instead of alkaline. Different chemical makeup, less power but less prone to leak.

Obviously YMMV and this is just me but I don't mess around with C- or D-Cells if I can help it. Bad enough that some things require a 9v! I have standardized around CR123a, AA & AAA although I'll admit that I've been moving slowly to 18650s where I can. The new breed of uber-weaponlights mostly run on the high powered rechargeables so I'm moving in that direction as much as I can.


IMO most "serious lights" run on either CR123a or 18540 batteries.