I have to agree with Boaz. My lithium ion batteries don’t seem to mind the cold at all. I recently purchased some Tenergy NI-MH D batteries. I was going to a christmas party at the lake & thought I would try to get some beamshots. I loaded my TK70 up with freshly charged batteries. We got to the party it was from 18:00 to 22:00. I left my Fenix in the car. The temp outside was about 20 degrees. I came out to do some beamshots. The light instantly started kicking down to 900 lumen mode and would not hold the 2200 lumen mode. I thought there was something wrong with the light. I wondered if the cold had such a adverse effect on the batteries. When I returned home I switched to my spare set and the light worked fine.
Alkalines don’t like the cold. Anyone whose lights may freeze ( keeping in a car in northern climes) should use lithium primaries. They can be frozen with no adverse affects.
I keep all my 12 volt Lithium ion DeWalt in the work van which is in a unheated garage.
The flashlight works fine and all the drivers work fine first thing in the morning.
Going to be below zero next week so I will have to check the output with my light meter.
I did some testing of A123 LiFePO4 cells here: A123 capacity vs charge voltage (and other effects) | Endless Sphere DIY EV Forum
One of the tests was with the cell fresh out of a freezer. Capacity was not affected, but its ability to supply power/current was… until it warmed up. LiCo and LiPo cells behave much the same.
How are the FastTech “Nice” batteries? Are they as good as Energizer Lithiums?
Wow, that was very thorough test.
Do you happen to know how long this A123 LiFePO4 battery can last? Is it possible to last 10 years?
My former job involved testing high capacity Li-Poly and LiFePO4 batteries in extreme conditions. (for reference, Li-Poly and Li-Ion behave in a similar way). At temperatures below 0C, Li-Ion begin to lose a little capacity. At –20C, Li-Ion really start to fall down. They give up about half of their capacity and resist a charge (temporary jump in internal resistance, known as charge acceptance).
LiFePO4 perform much better, with a 33% loss and better charge acceptance. There are a few variations of LiFePO4 formulations which are mostly unidentified. The newer ones perform much better in the cold.
Specifically referring to usage in flashlights (3W and higher, anyway); even if the cell starts out at –20C, it will not be there for long. The emitter and driver will warm up the host and battery and things will return to a normal condition.
One final note: Avoid charging Li-Ion cells when they are below 0C. This has shown to produce small amounts of lithium metal deposits on the anode. While probably not dangerous (lithium metal is highly reactive), it does permanently degrade the cell.
OK, just one more note… If you need batteries that can take abuse at the expense of capacity, go with LiFePO4. They dish out high currents, not as picky about charging end voltage, and inherently stable at high temperatures (no thermal run-away like Li-Ion).
Yes, at least the A123 ones should. I have some that were made in 2006 (?) and still are going just fine. In fact they were stored on a shelf for over 4 years had still held most of their original charge.
That’s for sure, I used Li-ion batteries for my camera at –18C before (not in MY, it never ever go under 25C here). Never have I seen such poor performance, it simply just “discharged” so quickly. I normally can go 2 days snapping pics per battery on vacation (not very trigger happy), but under cold, I hardly can do half a day. I didn’t expect that so I just had to take pictures more sparingly, kinda ruined the vacation a bit.
If it’s very cold, Li-ion just won’t do the job.
Here’s a post I did about using 4 A123 cells to start a car in –20C weather:
I’ve had enough of our cold spell. We had a high of 7f today. My old h.s. buddys parents would store their alk batteries in the fridge…so they’d keep longer. I don’t know if there was any truth to that.
It actually slows the self discharge a bit. OK to do if you buy bulk and plan to keep them for a long time.
I just do it because if placed elsewhere I’ll simply lose them. 
Nice to know it works so well.
Not knowing much about car starter, I wonder is it because A123 bring the voltage of that car battery up to above 13V that make the car start, or it is the A123 alone started that car? Can it be done without the car battery? A123 cost about USD12 per piece, why car manufacturer don’t put A123 in car battery. The higher the volume, the cost will be lower.
No car battery:
LiPo battery integra engine cranking test, Turnigy Nano-tech 45-90C
But even a lower powered Lipo will do:
Jump start a 4x4 with a Hobby King Turnigy LiPo battery
Why don’t they use lipo’s or A123 in a car?
Pb batteries have been used for a very long time and they fit well into the old electric system of the car. You can abuse them a lot and they don’t care. Lipo’s lose capacity a lot when it’s cold and also cannot provide high amps. I guess they are even worse at that than Pb batteries. Pbs are easy to charge, Lipos not so much. Density is probably better with Lipos than Pbs. Weight as well. Maybe some racing car batteries are not based on Pb, who knows.
In electric cars they prefer and learned to use Lithium based batteries.
Dunno how it is with charge and discharge of Pb vs Lipo or LiFe.
Lion seem to have very low discharge rates compared to Lipos. A cheap Lipo I have is rated at 120-240A. So it could do 100A I think. On the other hand when I look at Lions, they seem to die when you go past 5A, their voltage drop is huge and internal resistance as well.
But in the previous video, it shows that A123 still able to start car engine when PB battery can’t at –22 temperature. Doesn’t it mean A123 is better. Maybe have to put them in the trunk to avoid heat from car engine so that it doesn’t get too hot.
Lithium based cells handle cold better than many cells (Although they are still effected) including lead acid and nimh. That said they aren’t ideal for cars since they do have a specific nature that takes less abuse than lead acid battery’s that are commonly found in cars now, but newer lithium based cells are making their way into cars.
Race cars often don’t have batteries, they are started on the line and left running; no extra weight involved (Although newer ones are having small Pb, lithium and other cells placed in as an fail-safe and to power the electronics).
Higher density lipo packs would be a much better choice that 123A cells for car use too ;). A bunch of small cells in series is a bad idea.
The A123 cells can deliver over 200 amps! 4 of them in series match a car battery voltage almost perfectly and can start most cars without any other battery. Those 26650 cells are only 2300 mAh, not enough to be used as the only battery in the vehicle.
I have built a couple of lights that use the A123 cells that have a connection for connecting jumper cables.
A123 also has some wicked 20 Ah pouch cells that can dump over 1000A. You can find them on Ebay for under $30 ea.
So, in cold conditions you might be better off with overdriven flashlight 
Comparing, say 0,5A and 3A, if high amps heat the cold battery better?