Fenix LD12 and cold-weather

Hi , I’ve got a LD12 + eneloop THAT don’t light at all when temperature is like 0 degres celcius (with wind) .

Why ?
When i recharge this frozen eneloop , it can recharge 700 mAh (eneloop = 2000 ma) so it was not discharged.

I’ve just bought an olight s15r , hope it will go with that.


My first thought is battery issue, but from Panasonic’s webpage:

The performance of every battery will be less at low temperatures.
The internal resistance is hihger at low temperatures, that is not a big problem for a bike taillight with a small red led, but most flashlights need a lot more power.
With the higher internal resistance the voltage will be too low if the current is high.

I use low selfdischarge batteries in the tail light of my bike, and there are no problems with low temperatures.
The front light works on a 8x 18650 battery pack, the capacity of that pack is much less at temperatures below 0°C.
The bike computer Always displays “low battery” if the temperature is below –5°C, even with a brand new 2023 lithium battery.

The Fenix LD12 uses only 1 battery, if the voltage of that battery is too low (under 1,2V ?) the flashlight probably won’t work.
I had a Fenix LD20 (2x AA abttery) and that worked fine with nimh cells at low temperatures.

The same happens with my eneloops in blf348 and lumintop tool in the very cold. Best solution is to use something like energizer ultimate lithium when it’s cold out.

I just did some tests with a Tank 007 TK-568 and a Fenix LD15.
Both flashlights were in the freezer for more than one hour (–18°C).
The Fenix works fine at low temperatures with a white Eneloop battery.
And the Tank 007 also works fine at low temperatures with a GP Recyko.

Both batteries were charged more than 1 year ago, the Recyko is about 6 years old, the Eneloop is only 3 years old.

So i think the LD12 should also work in very cold conditions with low selfdischarge batteries.
But it is possible that the LD12 needs a slightly higher voltage to let the elektronics (led driver) work like it should…

Pop a decent lithium in there. If it works when cold with a lithium, then it’s probably a battery voltage issue.

Those bateries are not recharbeable is’nt it ?

And, what about 14500 li-ion 3,7V : Will it work with ld12 ? … i know Fenix said “14500 banished”

ps : I think it’s unbielivable that fenix does’n mention this problem of temperature. Customers of fenix are generally tank-people that needs reliable equipement !

pps : Thank every one , my english is quiet bad, i’m from France.

0 degrees Celsius is not ‘cold’, and I doubt it’s a battery issue. The OP says his LD12 won’t work at all - which might indicate a break in contact as the metal contracts, or a lubricant becomes thicker and prevents proper contact.

I’d try cleaning the mating surfaces of the tail cap and the end of the battery tube with a Q-tip and a bit of rubbing alcohol, then checking to make sure the driver assembly is tight, and making sure the switch assembly is tight in the tail cap. If none of those have an effect, there may be a fault on the driver board itself where contact is adequate when everything is well expanded, but open when everything contracts in the cold. The latter seem unlikely, as the driver should generate enough heat to keep itself warm - I’d look at the lubricants and tightening the switch internals first.

Once you have it running, will it stay running? Can you warm it enough in your hands to start it running in the cold?

When the light is “frozen” , i can change the baterry from one-warm-from-my-pocket and with that, it re-work . Not for a long time…

Also , When it didn’t light up , if i push de two buttons (2 buttons in ld12) during 10-20 seconds , it light up sudenly , if i turn off it turn of for eternity.

I’m considering it’s maybe the contact … because ld12 needs to be perfectly-perfectly screwed to work.


After asking Fenix many question about my problem , they are finishing by ignoring me.
Fenix , good-bye.