# Cold performance: NiMH vs Li-ion rechargeables



## zorobabel (Oct 16, 2017)

I haven't been able to find a clear answer on this, which one performs better in cold temperatures? Let's say AA Eneloop vs 14500 to stay with the same volume. By cold, I mean 0F/ -18C. I've seen charts specifying -20C to 60C as operating temperatures for both of these types of rechargeables, but nothing on performance. Opinions based on real world usage are welcome.


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## AB8XL (Oct 16, 2017)

found this: http://www.candlepowerforums.com/vb...-Best-battery-chemistry-for-cold-temperatures


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## zorobabel (Oct 16, 2017)

Thanks! It does not seem to address Li-ion rechargeables, only Lithium primaries.


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## AB8XL (Oct 16, 2017)

I would suspect the same rules apply, thus reasoning for the automotive segment moving to Li-Ion, but also for weight and energy density reasons too.


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## xxo (Oct 16, 2017)

IIRC eneloops are rated for as low as -20C/-4F, lithium ions* are roughly the same (you will need to check the specs for the exact cell you are interested in). Energizer ultimate lithium (primary/not rechargeable) batteries are rated down to -40.


*Lithium Ion batteries can be used at below freezing temps, they should not be charged below 0C/32F, same thing with charging NiMH's.


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## StarHalo (Oct 16, 2017)

You shouldn't expose any kind of rechargeable cell to temps that low, 0F is when they begin to become damaged, which means loss of capacity/mAh. If your light is going to be out of pocket for some time in anything under freezing, go with lithium primary.


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## zorobabel (Oct 18, 2017)

StarHalo said:


> You shouldn't expose any kind of rechargeable cell to temps that low, 0F is when they begin to become damaged, which means loss of capacity/mAh. If your light is going to be out of pocket for some time in anything under freezing, go with lithium primary.


 Thanks for replying. From that point of view, would you say AA flashlights are superior to 18650 flashlights because they can take AA lithium primaries?


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## weez82 (Oct 18, 2017)

zorobabel said:


> Thanks for replying. From that point of view, would you say AA flashlights are superior to 18650 flashlights because they can take AA lithium primaries?



No. You cant say a light is better because of battery type. Way too many lights on the market. A light that can take an 18650 might be able to use two primary cr123's. Just depends on the light. Also keep in mind that the temp outside might be -20 but that doesnt mean the light will be. That also depends on how you carry the light. If you keep it in your pants pocket it will stay warm because of body temp. And when using the light it will be in hand shielding it somewhat from the cold. 

Too many variables at play. Get the light that fits your need


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## StarHalo (Oct 18, 2017)

zorobabel said:


> Thanks for replying. From that point of view, would you say AA flashlights are superior to 18650 flashlights because they can take AA lithium primaries?



Plenty of advantages and disadvantages to each, that's why both still exist.


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## zorobabel (Oct 25, 2017)

Thanks for the replies, I forgot about CR123s. CR123 primaries seem to work to -40C while AA lithium primaries to -60C.


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## archimedes (Oct 25, 2017)

More details of your usage scenario might be helpful for others here offering advice, if you'd care to share those....


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## zorobabel (Oct 25, 2017)

archimedes said:


> More details of your usage scenario might be helpful for others here offering advice, if you'd care to share those....


 Primary usage is hiking, backpacking, climbing including in winter, mostly in the Sierra Nevada in California, but other areas as well. Secondary usage is working on cars, but any work in the cold would be unplanned. I already bought a Thrunite TH20, which made the other (10y old) headlamps we have seem inadequate. I want to buy a second HL, so my wife doesn't get to complain that her HL is garbage.


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## Phlogiston (Oct 27, 2017)

Here's an old thread where we were discussing Li-Ion and CR123A performance in cold conditions: 

http://www.candlepowerforums.com/vb...re-performance-rechargeables-18650-vs-RCR123a

My post there includes links to some sample Li-Ion data sheets and a bit of discussion of what those specifications might mean for cold-weather use.


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## Gauss163 (Oct 28, 2017)

Be sure to understand the crucial role played by self-heating. For example, if aggressive UVP terminates the discharge before self-heating fully kicks-in then you might get only 1/20'th of the actual capacity available at that temperature (depending on the cell's IR / impedance). See this post and this one further discussion, including a graph.


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## zorobabel (Oct 30, 2017)

Thanks Phlogiston and Gauss163!


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## Woods Walker (Oct 30, 2017)

I have yet to fully test Lithium ion flashlights though know from experience cameras using lithium polymer batteries die in the cold. I do fully know NiMH in the cold is a problem. I shield a 18650 by using a Fenix HP12 which allows me to keep the battery under my hat which is warmer and the LED in the cold. Kinda the best of both worlds. Overall for cranking cold my advice is to use lithium primaries. One less thing to worry about. My coldest battery usage for a light was around -25F sleeping out. Not sure what the wind chill was but not good.


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## StarHalo (Oct 30, 2017)

Woods Walker said:


> My coldest battery usage for a light was around -25F sleeping out. Not sure what the wind chill was but not good.



That's cold enough to get some lubes to fail, you might actually have a seized light until it warms oo:


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## Scott Novak (Dec 31, 2017)

Here are a couple of Panasonic NiMH cells intended for low temperature operation. I don't have any experience with them as I just discovered them online tonight.

BK250A : Low temperature discharge type (NiMH A Cell)
https://industrial.panasonic.com/ww...l-metal/Low_temperature_discharge_type/BK250A

BK130AA : Low temperature discharge type (NiMH AA-Cell)
https://industrial.panasonic.com/ww...-metal/Low_temperature_discharge_type/BK130AA

I recently purchased a 1200 lumen bicycle light with a battery pack with four 2,200 mAH Li-Ion cells in it. At 80 degrees F it will run for over 2 hours. However, at 20°F in will only run for 12 minutes. I'm not sure how much of the problem is the actually Li-Ion cells and how much is the undervoltage protection circuit tripping too early.

After looking at a lot of Li-Ion information I've come to the conclusion that at present Li-Ion cells aren't that suitable for winter use in Minnesota.

Check this out: Study on Low Temperature Performance of Li Ion Battery
https://www.scirp.org/Journal/PaperInformation.aspx?PaperID=80512

Look at figures # 4, 5, and 6. At higher current drains the internal resistance of the battery has become so high that there is nearly no output at -22°F (-30°C).

I think what it may indicate is that a Li-Ion cell with very low internal resistance (High current output / High drain) may perform better and provide more mAH of output than a lower drain Li-Ion cell with a higher mAH rating at higher temperatures.
I suspect that some of those high current Li-Ion cells designed for vaping devices might work better at lower temperatures. Alternately you may need to connect multiple Li-Ion cells in parallel to obtain sufficiently low internal impedance at low temperatures.

Until I obtain different batteries, I've put the Li-ION battery pack into one of the panniers on my bicycle stuffed full of insulation. It has extended the run time substantially in this subzero weather. The other option if to fashion a harness to hold the cells next to my body to keep them warm.

Previously, I was using a modified Stanley spotlight with a 540 lumen output on my bicycle. I gutted the electronics and ran the LED array directly from a 4 pack of NiMH AA cells in series using a power MOSFET to turn the power on and off. It actually performed fairly well in subzero weather, until it was stolen.

Scott Novak


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## Gauss163 (Dec 31, 2017)

Scott Novak said:


> [...] Check this out: Study on Low Temperature Performance of Li Ion Battery
> https://www.scirp.org/Journal/PaperInformation.aspx?PaperID=80512
> 
> Look at figures # 4, 5, and 6. At higher current drains the internal resistance of the battery has become so high that there is nearly no output at -22°F (-30°C). [...]



*Beware*: Do not trust the results in that paper, since the publisher _Scientific Research Publishing (SCIRP)_ is a Chinese vanity press, so the paper is unlikely to be peer-reviewed, so could possibly be completely fake (e.g. the above-linked Wikipedia page mentions SCIRP accepted a paper written by a random text generator).

There is plently of literature in reputable sources on low-temperature performance of Li-ion batteries.


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## campingnut (Dec 31, 2017)

When I was yonger, we would camp in the snow during hunting season. Our base camp was at 10,000 feet and night time temps would drop to -20 f. I would always place my flashlights and extra batteries in my sleeping bag with me at night to keep them from freezing. During the day, when it would warm up to 8 f or so, I would carry them. I never left them out...too cold.


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## campingnut (Dec 31, 2017)

BTW...we also did the same with the toothpaste and sunscreen...lol


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## Boris74 (Dec 31, 2017)

Before this year I only used primaries. When it got cold, that meant lithium. I made a complete switch to rechargeable for everything this year. So far this winter has been cold and February isn’t even here yet, going to be a fun one. I’ve been using my 18650 and 16340 lights in the cold recently by cold I’m talking +8F has been the warmest it’s been in over a week and -20F and colder has been normal lately. 

Some regular Streamlight 18650s have been doing fine, but at lesser run times. I don’t mind, I always have spares on me. I got a Nitecore low temp performance cell and it lives up to the claim. It sat untouched at -18F for a few hours and fired right up like it was just brought out from a warm house. Ran longer than I need it to that night, no swap out needed. Oh but cell life is shorter, don’t care, I’ll buy new ones. When I need light I need it, I can’t wait until summer to use the lights, they’re tools and they will be used when needed and batteries will be replaced when needed. As it sits, even with shorter run times on the Streamlight brand 18650s, they’ve already paid for themselves more than a few times over. It’s all free from here on out. If I still used primaries, I’d be shelling out the dough to keep them working. 

That nitecore cell though, it’s a hard hitter, even when it's well below 0F. I’d say worth the price and I’ve used it nightly for the last week and it has yet to be used above 0F. 

The olight H1R headlamp don’t seem to be effected at all, but it probably stays plenty warm being on my head. S1R does fine too but it don’t sit out, it stays in the pocket until needed and don’t really get too cold, if it comes out of the pocket it's turned on. Them high drain cells do good in the cold as far as I can tell. Haven’t used any of the 14500 lights outside in the cold. They either just don’t run long enoug for work lights or don’t throw enough for my typical outdoor use.


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## TwiceFuzed (Dec 31, 2017)

My new 1900 mah 4th gen eneloops have been doing fine in the cold, its been down to about 10F here the last few days. I have a couple of 18650 lights that don't do well at all in the cold. So far the nimh batteries are doing fine for me in my EDC light, a Lux Pro LP290. My flashlight runs strong at these temps, I haven't had it quit me yet, I usually swap out and recharge the batteries every 4-5 days. My iPhone will die in minutes out in the cold, despite being in my pocket. It will sometimes die at a high battery percentage, 60+%. I haven't had a rechargeable lithium ion of any kind yet that performed well in the cold.


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## Scott Novak (Jan 1, 2018)

Thanks for the tip on the Nitecore Li-Ion cells. I looked at the Nitecore NL1829LTP and the NL1829LTHP and the cold weather performance looks pretty good. But I choked when I saw the $24.95 price tag. Especially considering that I need at least four of them to obtain the run time that I need.

I did a rough comparison between the Panasonic BK250A A size low temp Ni-MH and the NL1829LTP 18650 size Li-Ion.

It would require four of the Ni-MH A size cells to approximate the low temperature capacity of one NL1829LTP Li-Ion cell.

The four Ni-MH cells would weigh about 3 times more than a Li-Ion cell.

The four Ni-MH cells would have about 20% more normal temperature capacity than the Li-Ion cell

It would cost $17.88 for four of the Panasonic BK250A Ni-MH cells vs $24.95 for one NL1829LTP Li-Ion cell.

For the cold weather performance that I want I would need 16 of the BK250A Ni-MH cells @ $71.52 - @640 g, or 4 of the NL1829LTP Li-Ion cells @ $99.80 - @150 g.

That would be about 1 lb more to use the Ni-MH for my bicycle light, but $28 less than the Li-Ion.

Then deal with charging 16 Ni-MH cells vs 4 Li-Ion cells.

Trade offs any way that you look at it. But for a bicycle application, one pound less would tip the scale in favor of the Li-Ion.

Scott Novak


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## lumen aeternum (Feb 19, 2018)

So what's the best solution for a car emergency light -- Lithium primaries, or something like the mag-charger light that is always on trickle charge? One would think that the trickle would keep the battery warm.

I've never seen a battery sales description that talks about cold weather performance. A thread with a list of specifically cold weather batteries would be a good sticky.


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## StarHalo (Feb 19, 2018)

lumen aeternum said:


> So what's the best solution for a car emergency light -- Lithium primaries, or something like the mag-charger light that is always on trickle charge? One would think that the trickle would keep the battery warm.
> 
> I've never seen a battery sales description that talks about cold weather performance. A thread with a list of specifically cold weather batteries would be a good sticky.



The catch is that the flashlight will eventually have to be used, which may include being set down for a period of time; doing engine work at -10F will start to damage a rechargeable cell after a while, whereas the lithium primary will continue functioning without issue.


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## lumen aeternum (Feb 19, 2018)

Scott Novak said:


> Here are a couple of Panasonic NiMH cells intended for low temperature operation. I don't have any experience with them as I just discovered them online tonight.
> 
> BK130AA : Low temperature discharge type (NiMH AA-Cell)
> https://industrial.panasonic.com/ww...-metal/Low_temperature_discharge_type/BK130AA



The discharge curve is at 20 Centigrade. Not at all a low temp!!!


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## Scott Novak (Feb 19, 2018)

[h=2]Low Temperature Li-Ion 18650 Test[/h]I used a Bright Eyes bicycle light advertised @1,200 lumens and it's 4,400 mAh Li-Ion 2S-2P 8.4V battery pack. The Li-Ion cells were unmarked. I believe that the actual output is about 350 lumens. The light uses a buck converter rated for 5VDC to 20 VDC input and the driver is constant current.

These 18650 Li-Ion cells were allegedly rated 2,200 mAh. The Bright Eyes light kit package was sealed until opened about 2 weeks before this test. The battery pack was used about 6 times with approximately 4 hours total use.

If the battery pack was outside for more than 30 minutes @20°F, there was less than 12 minutes run time on high before the battery pack shutdown.

*Test #1*

The Bright Eyes battery pack was fully charged.

The battery pack temperature was 80°F

I placed the fully charged battery pack in a 4.9°F freezer with Bright Eyes light outside of the freezer.

I turned the Bright Eyes light on high.

The battery voltage steadily declined until low voltage shutdown occurred @5.80 VDC @0 hours, 22 minutes.

I allowed the battery pack to warm to 80°F.

I turned the Bright Eyes light on high.

The battery voltage steadily declined until low voltage shutdown occurred @6.14 VDC @0 hours, 56 minutes.

The no load voltage was 7.58 VDC.

The total run time cold and warm was 1 hour, 18 minutes.

+++++++++++++++

*Test #2*

I disassembled a dead aftermarket battery pack from a Mac Laptop computer. Four of the six cells were still good and had some charge left in them. The battery pack was at least 4 years old. The 2,600 mAh 18650 cells were marked: ASO FK1K031EG 814793 SZN with a sea foam green sleeve.

I removed the battery protection circuit from the Bright Eyes battery pack and wired it to these recovered batteries in a 2S2P configuration.

The battery pack was fully charged.

The battery pack temperature was 80°F

I placed the fully charged battery pack in a 4.9°F freezer with the Bright Eyes light outside of the freezer.

I turned the Bright Eyes light on high.

The battery voltage steadily declined until it reached 6.10 VDC @1 hour, 23 minutes.

The battery voltage then began to rise until it peaked at 6.43 VDC @1 hour, 56 Minutes.

The battery voltage steadily declined until low voltage shutdown occurred @6.01 VDC @2 hours, 58 minutes.

The no load voltage was 6.83 VDC.

I removed the battery pack from the freezer and I measured the battery case temperature @41°F.

Total run time 2 hour, 58 minutes.

I did not perform an additional test after the batteries were warmed back to 80 degrees.

I believe that the battery voltage rise was occurring because the internal resistance of the battery was rising significantly and causing heat to dissipate inside the battery, which allowed the battery to output voltage longer.

These tests were performed with generic Li-Ion batteries. There are some Li-Ion cells that are formulated to operate at low temperatures.

Nitecore makes low temp rated Li-Ion cells:

http://flashlight.nitecore.com/product/nl1829lthp

http://flashlight.nitecore.com/product/nl1829ltp

Whether or not these cells are actually formulated for low temperatures or not is a good question. They may just be a regular low internal resistance high current cell that works better at low temperatures that the standard high capacity cell because of the lower internal resistance

Scott Novak​​


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## sbslider (Feb 19, 2018)

Boris74 said:


> S1R does fine too but it don’t sit out, it stays in the pocket until needed and don’t really get too cold, if it comes out of the pocket it's turned on. Them high drain cells do good in the cold as far as I can tell.


My experience with the S1R, at least on turbo mode, supports keeping the battery warm. Letting it get down to near+10C causes significant performance change. 

You can read about a test I performed here


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## Gauss163 (Feb 19, 2018)

Scott Novak said:


> [...] I believe that the battery voltage rise was occurring because the internal resistance of the battery was rising significantly and causing heat to dissipate inside the battery, which allowed the battery to output voltage longer. [...]



IR (internal resistance) typically increases greatly at colder temps. This extra resistance will generate extra heat, which will warm up the cell so decrease its IR, hence decrease the total voltage sag due to IR. This "self heating" effect shows as an initial V-shaped dip in the discharge graph (presuming that the initial sag minimum was not so low to trigger low-voltage shutoff before self-heating caused the voltage to start rising), e.g. see the lowermost black curve below.

Designers of li-ion powered devices used in cold temps may exploit this by designing enclosures that attempt to retain the generated heat in order to speedup the self-heating process hence minimize the energy lost due to overcoming the extra resistance at lower temps. Hobbyists often use body heat for this purpose.

When performing comparisons such as those above it is important to attempt to _equalize _these self-heating effects. For example, if one pack was enclosed in a case then it will better retain the heat so it will heat up more quickly than one not encased. This can make a big difference in the measured capacity. Such considerations are essential if you intend to measure only the performance of the cells - independent of external thermal factors such as heat flow of the cases, etc.


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## Woods Walker (Feb 20, 2018)

I tested a Nitecore battery at 5 degrees. Lithium ion made for the cold. Ran the high draw XHP-50 Wizard just fine. I really wanted sub zero but it's supposed to be 70 tomorrow. Dang..... On a side note did camp in -5 to -10 (someplace in the middle at my location) this winter. All failed except lithium Primaries CR123. I didn't have the new 18650 battery and there was zero scientific controls. Only me and the woods for days sleeping out.


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## Woods Walker (Feb 20, 2018)

My overall impressions from field use is NiMH fails in the cold more so than lithium ion.


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