Cold performance: NiMH vs Li-ion rechargeables

[campingnut]

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

 

[Boris74]

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.

 

[TwiceFuzed]

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.

 

[Scott Novak]

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

 

[lumen aeternum]

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.

 

[StarHalo]

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.

 

[lumen aeternum]

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!!!

 

[Scott Novak]

[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]

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

 

[Gauss163]

[...] 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.

 

[Woods Walker]

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.

 

[Woods Walker]

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