Cold performance: NiMH vs Li-ion rechargeables

zorobabel

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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.
 

AB8XL

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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.
 

xxo

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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

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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.
 

zorobabel

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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?
 

weez82

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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
 

zorobabel

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

zorobabel

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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.
 

Gauss163

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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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Woods Walker

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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.
 

Scott Novak

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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
 

Gauss163

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[...] 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.
 

campingnut

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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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