Lanterns and Battery Banks in Extreme Cold

Hi Volker, I spent a lot of time investigating this a while back.  My conclusion was to stick to lithium ion and double or triple the battery capacity beyond what you need in summer.  It led me to the Fenix hm62t with its large rechargeable battery and light magnesium body.

Disposable Lithium batteries hold charge better in deep cold than even lithium ion, but they’re a bit expensive, you may need to carry backups and then there’s the extra ewaste

Thanks David.

I’ve gradually upgraded to increasingly power dense lithium ion power banks. You get much more mAh per ounce the larger the battery is (sort of like in real estate you generally pay less per square foot the larger your apartment is). For a while I was rocking dual 33,800 mAh banks that each weigh 11oz. Now my standard go to is a single 50,000 mAh bank that weighs 12oz. This is plenty to recharge my phone several times over 3 or 4 days with a good bit left over. Sometimes I will carry a separate much smaller battery like the Nitecore 10,000 mAh for 5.5oz, or the Nitecore 6,000 mAh for 3.5oz. These small ones are good for powering things like a dimmable ridgelight or a fan in summer heat and as an emergency backup [never wise to have all your eggs in one basket].

I’m already set with my Nitecore headlamps so I don’t need the Fenix HM62 T. I use the Nitecore NU25 – 400 lumens 1.6oz, and NU27 600 lumens 1.9oz for ultralight, and when I want to do evening walks in winter, I’ll bring the beefy Nitecore HC65 2,000 lumens for 5.4oz. Naturally I mostly use much lower settings than the brightest to preserve battery life.

According to google, Lithium ion battery banks generally work to charge things down to around -4F. But what is bad is to charge them up below freezing. That is easy to avoid. I bring a big battery bank so I don’t need to recharge in the field and there’s no outlet in the woods to recharge it from anyway. And I keep it in a ziplock bag to protect it from getting wet. And obviously you can store it in your pocket near your body heat to obtain a more functional temperature as you would your phone.

But since lanterns are meant to light up your campsite – maybe hanging from a tarp, they don’t benefit from being near your body heat. One idea I’m gonna try this winter is using a Nitecore Thermacell (electronic mosquito repeller) as a hand warmer. This in turn can work to heat up things like a butane canister, or a battery bank. Or I could turn it on and tape it to a lantern to keep the lantern battery warm enough to work. But this would be quite a complex workaround.

It occurs to me that another strategy for a working lantern in extreme cold is to place a white translucent bag over a headlamp and hang it from that. Headlamps seem to be much better than most lanterns in deep cold. The bag will diffuse it into a reasonably soft glow. And of course you can attach the headlamp to your head when you want to go for a walk so it becomes a dual use item. But a dedicated headlamp and a beefier headlamp as a lantern in a white bag is even better.

A white DCF stuff sack cinched around an NU20/25 hanging from a branch or rope makes a great camp lantern for under 2oz and is multi purpose.

This is brighter and better than any dedicated camp light I’ve tried

An excellent point Marcus. I think you are right. I can also put my dimmable ridgelight in a white bag and it makes a very bright and adjust lantern with a warm glow. But your solution is the ultralight solution.

So I could wear my NU25 on my head, and put the NU27 in a bag for a lantern or vice versa – and make use of the color temperature adjustment feature. Together, those two provide a good amount of ambience and functional light for less than 4oz. The headlamp internal batteries seem to be much more cold resistance than those used in most lanterns.

I can also use an 18650 battery in my HC65 to do this. I’ve got spares of that battery I can bring. I think those batteries do well in cold too.

Still I do like the ambience of a dedicated lantern. I might go ahead and try the Biolite Luci inflatable lantern. I knows those aren’t designed to work well below freezing but I think they can take some cold weather. They are also a bit harsh and not well diffused but my frosted Luminaid inflatable cube light doesn’t hold air very well now.

your NU25 will run from external power (or look for a light without built in battery). Keep a USB powerbank next to your body (under your jacket, inside your sleeping bag, etc) and run a usb-c cable to the light.

Since you had good luck with Nitecore batteries, they sell a bunch of models with a diffusing stuff sack.  ChatGPT:

I’m seeing a trend to string lights for some thru hikers, but cold weather performance TBD.  e.g.: https://www.rei.com/b/nite-ize/c/electric-lanterns

I’ve seen this get some traction for diffuse light use: https://claymoreoutdoor.com/products/capon-40b  but again battery in cold is TBD

Then there’s DIY for the brave (put in a diffusion sack).  If you have a known good battery, its solves that problem

• 2g, runs off charger: https://www.ebay.com/itm/123830611583   or
• https://www.amazon.com/HiLetgo-10PCS-Laptop-Keyboard-Camping/dp/B00MEKUSR4/ (Teran played with these IRCC?)

From my battery research when I bought my snowshoeing headlamp from the little public info available and acknowledging that performance can differ brand to brand:

• Disposable Eveready lithiums (available in AAA, AA, CR123A) are the most-cold tolerant but expensive.   ~ 75% rated capacity at -20C @ 1amp draw
• Li-Ion are the next best for cold, ~ 60% rated capacity at -10C, 50% rated capacity at -20C, ~ 25% rated capacity @ -40C
• NiMH are not good in cold, ~ 80% rated capacity at 0C, 20% rated capacity at -20C
• Avoid Alkalines, they freeze below 0C

Flexibility Zero Lantern (Ali Express)

DIY

Thanks Terran. I just got a chance to look into the Flextail Zero Lantern. It is very impressive as an ultralight backpacking lantern. Weighs 2oz. Does a very warm 3000K 360-degree Ambience Camp Light mode: 300 luments for 3 hr, 150 lumens for 5 hr, 75 lumens for 10 hr, 10 lumens for 35 hr. Also has an ultra cold 9000K Strobe/Flashlight mode: 200 lumens for 5hr, 130 lumens for 7 hr, 80 lumens for 10 hr, 50 lumens for 15 hr. Battery is 1100 mAh rechargeable via USB-C (but non-user replaceable). Waterproof rating is just a mediocre IPX5.

I don’t know anything about this in terms of cold weather performance. But I love the ultracompact form factor, warm light paired with flashlight abilities, lumen and duration specs, and low weight. And the price is very cheap at $14 on Aliexpress.

I’ll have to read up on some reviews of this light.

I placed an order for the Fenix CL26R (Non-pro model) lantern with 400 lumens. I got it for the explicitly stated cold weather resistant design. Also like that it’s powered by a user-replaceable 18650 battery. It comes with a 2600 mAh battery – recharged via micro USB. But I can use it with one of my 3 Nitecore 4000 mAh batteries which I also use in my HC65 Headlamp. So the lantern makes my investment in those batteries a dual use item for both the lantern and headlamp. I can have one or two spares ready to go if I use the lantern or headlamp or both on a trip. Chances are if I use the lantern a lot, I won’t run down the headlamp so much. I enjoy the strong output of the headlamp for night walks – so if I use it that way – then I won’t use the lantern so much.

I avoided the new CL26R Pro model – even though it is a bit brighter and uses USB-C to charge a 21700 battery. I think 18650 batteries are a better form factor for a powerful headlamp. Using a 21700 battery for a headlamp becomes too cumbersome and uncomfortable to wear on the head. Therefore a lantern and headlamp combo that both use 18650 batteries seems more optimal which is what I went for.

The color temp of the CL26R is sorta neutral. Not warm but not too cold I think. With the 4000 mAh battery I have, I’ll get about 7.5 hrs at 400 lumens, 23 hrs at 150 lumens, and 45 hrs at 40 lumens.

The battery chamber is housed in close proximity to the LEDs. So the heat they generate should help keep the battery from getting too cold in extreme cold. As a test, I put my HC65 headlamp with a Nitecore 4000 mAh 18650 battery in the freezer for an hour. It had no trouble turning on and the battery showed no drop down from 4 full bars of charge.

So I’m optimistic that the Fenix CL25R shouldn’t crap out in sub freezing temps on me this winter. Yes you can just use a headlamp or put one in a white bag to help diffuse and spread the light. But a dedicated lantern adds more ambience to a campsite. The weight with battery of 5.9oz is fine to me to get the specs it has in super cold weather.

I’ll report back here come winter to share how I make out with it.

That Fenix looks like it would do the job.

I got two of the Flextails. They’re a bit underwhelming. 300 lm for the lantern, 200lm for the flashlight.

The lanterns work well as chest lights. Bright enough without being too bright which can lead to night blindness. Good for a personal light. As a whole camp light, they’re a little too dim.

Using two lights for a freezer test. One as a control, one in the freezer. They’re rated for 3 hours on high.

I ran them for 1.5 hours last night before turning them off. Leaving one in the freezer overnight before turning them both back on for an hour before removing it for observation.

The freezer light appears to be a little dimmer. However it lasted longer and is still going while the control tapped out at just over 3 hours.

Just one trial done somewhat poorly. I need to switch the control. It does suggest the possibility of the cold throttling the power rather than limiting it. Or it could just be the lights themselves.

Yeah, I still think the CL26R should be more of an authentic camp lantern. Thanks for the caution on the limitations of the Flextail. I am still intrigued. Good freezer test. Keeping them both on shows the effect over time that the freezer might have on the battery capacity. And of course taking the freezer one out then causes condensation. My HC65 had no issues lighting up again despite condensation.

[As an aside: I recently learned you shouldn’t recharge a battery when it is cold because it will degrade and/or damage it. I haven’t done this to a battery bank. But I’ve done it to headlamps plenty of times. So I need to be careful to warm up a discharged headlamp in my pocket for at least several minutes before beginning to recharge it. And likewise I guess a phone should be warmed up near your body heat – before trying to recharge it when it has been in the cold.]

This gets into the issue of the size of the lantern and how concentrated the light output is. Sure a big heavy Coleman lantern that runs on butane will have a classic look, provide a good warm light with wide adjustability, but nobody wants to bring one backpacking.

Even as technology allows for higher lumen counts in an ever smaller and lighter device – the problem is that below a certain point, the size becomes too small to provide a satisfying light. A beachball sized light that puts out 800 lumens is nice but way too bulky. If you have a golf ball sized globe light that puts out 800 lumens – it will be far too intense to look at. Lumens, weight, and size are all factors. High max lumens with low weight in a compact form is good, but if it’s too small – the light doesn’t have enough room to spread out. The emitter is too concentrated.

This is where the inflatable lanterns make some sense. They expand in the field and provide a lampshade/diffusion effect which is more pleasant to look at. But a compact hardshell lantern with variable color temp, dimmable lumens, good red light mode, nice diffusion, light weight, high max output, user replaceable batteries, in a compact form factor (but not too compact), and reliable performance in extreme cold is still the holy grail. Five years from now, I’m sure there will be several new options that supersede these.

Does a very warm 3000K

This is interesting, and is probably a very personal thing. In person I’ve never seen or found 3000 Kelvin “very warm” – quite the opposite, in real life I find bulbs and fixtures as rated 3000K to be somewhat cool. In practice, 2800 Kelvin is what is thought of as “warm” and is generally considered to mimic incandescent light bulbs perfectly.

Regardless, a neat little light.

Still, I prefer the UCO in genuinely cold weather!

Well the lower the Kelvin, the more yellow the light. And the higher the Kelvin, the more bluish the light. Ironically, blueish light as with a blue flame is hotter than a yellow flame. But aesthetically we consider colors like blue and purple to be cold, and orange and yellow to be warm.

Appreciate the shout out for the classic UCO lantern. I’ve used mine on just a couple of trips. But I got so focused on reducing weight overall that I’ve forgotten to use it for several years. By this point I’ve lowered my weight on enough other gear categories that it’s certainly not a burden to carry. Hard to argue with the flickering ambience of a candlelight flame. And the natural heat it gives is a positive by product in cold weather. But it’s heat and brightness are very slight. And you have to manage the dripping of the wax which can be a tad messy at times. But undoubtedly a charming and classic choice. A little bit of light and heat is often all you need to make all the difference until the sun makes it’s way around again to offer you reprieve from a long dark winter night.

Well the lower the Kelvin, the more yellow the light. And the higher the Kelvin, the more bluish the light. 

Yes, understood. I had an entire semester of color theory in college as part of a fine art curriculum lol.

What I’m saying is I’ve never found 3000 Kelvin to be “very warm.” In fact, as a custom home builder, when I walk through lighting selections with clients the vast majority chose 2800K rather than 3000K. The only time I will typically use 3000K lighting is in bathrooms, garages, basements/crawl spaces and under-cabinet lighting. Most people (myself included) find it too harsh. My own home has 2800K cans throughout.

Anyway, yes indeed UCO – mine is an older USA made one. I’ve heard the offshore quality isn’t as good, but don’t know. Regardless, I just prefer a candle on the long, cold nights one spends in a tent.

Oh ok Brad – I didn’t realize you were being so specific.

I’m coming from having studied Nitecore Headlamps with Multi-Color Temps for which 6500K is cool, 4500K is neutral, and 3000K is warm.

I haven’t actually looked at a Kelvin meter as it measures color temperature of a light with a knob that can go from 6500K down below 3000K. So I wouldn’t know how discernable the difference is between 2800K and 3000K. But relative to a very cool or cold 6500K light, both and 2800K and 3000K would be considered very warm.

Flextail. Bright enough.

I decided to spring for a couple of the Flextail Zero lanterns. The price shot up from $14 each to $24. But that’s still a lot less than the MSRP of $50. The warm color temp is great to have in such a light compact form factor.

The Fenix CL26R non pro model came today. It’s a fairly cold LED I’m afraid. But I tested it out by placing it in the freezer alongside my Biolite Alpenglow Mini 150L light. I had them both on at 50% brightness and when I checked after 30 minutes the Alpenglow was off while the Fenix was on just as bright as before.

I took them out and was able to get the Alpenglow to turn on again. But then it went out again after 10 seconds just like I see on cold weather camping trips. I noticed in this state is shows only one blinking LED charge indicator so that means it is temporarily disabled from the cold.

Now over an hour later when the light has had time to return to room temp, I can turn the Alpenglow on with no problem. And it shows all 4 lights indicating a full charge.

The Alpenglow is a warmer LED which I like. But I know it craps out when temps go just a few degrees below freezing. The warm LED, compact size, and light weight of 3.5oz is great for the warmer 2/3rd of the year. But when the nights are long and cold, at least I know now the Fenix CL26R won’t let me down.