21700 is the future

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xevious
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hank wrote:
I admit I’ve often wondered if Zebralights were worth the prices asked, but I’ve never bought one (nor even seen one).

Yeh, if I add up what I’ve paid over the years for inadequate and poorly made lights, I could’ve had a couple of Zebralights.
Who knew?

Count me in as another Zebralight fan. They fly “under the radar,” so to speak. They look a bit… boring, compared to the glitzy lighted switch LED flashlights of today. Comparatively more expensive. And the UI is quite different. But after using Anduril, which I really enjoy, I’m fine with the Zebralight UI. I had an early SC52w that I loved, except for the tint. And these flashlights are seriously a pain to modify (costs more than buying a new light). So I sold it. Got myself an SC64c LE with Samsung LH351D. Very nice tint. It’s a bit longer than the SC52w, but you forget about it. Such a great light all around. And I love that e-switch. I do lean more towards the FW3A, because I’m enjoying Anduril & the flexibility (mods, optic swaps, etc), but my 2nd favorite is the SC64c.

I have to admit, I was tempted to get an SC700, and enjoy that 21700 cell. But it was a bit too big for what I wanted. I also considered the SC600, but the output isn’t an enormous jump from the SC64.

SKV89
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I tried a few Zebralights in the past because they are supposed to have some of the most efficient drivers. I realize I don’t like their UI at all but I can accept it since I’ve been EDCing Clemence’s Tiara Pros that have a similar UI. However, what I CANNOT get myself to accept is the bad tint. Greenish Cree emitters and tint shift. I think if they used a beaded optic, at least there won’t be tint shift. Now if I want a light with ultra high efficiency, I’ll just buy Olights though their emitter options are not too much better than Zebralight. But at least most of them are moddable.

how crazy is this
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xevious wrote:
I just recently had a TH20 modified to run a 219B emitter and it’s a beautifully warm tint. A little less throw, but I was more than willing to trade off some for a more eye friendly tint. It is, after all, designed to be a near-task light. I had no idea that a clip was available that could work for it. Thanks for mentioning!

Saw the clip idea somewhere and just tried it. I am also one who likes to tail stand a light. Looking at the TH20 the first thought is that it is not well suited for that purpose. Actually it is the best tail standing light I have ever used. Laid down, technically not tail standing, you can angle and direct the light like it is on a tripod. Way better than a flat ceiling bounce!

xevious
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how crazy is this wrote:
Saw the clip idea somewhere and just tried it. I am also one who likes to tail stand a light. Looking at the TH20 the first thought is that it is not well suited for that purpose. Actually it is the best tail standing light I have ever used. Laid down, technically not tail standing, you can angle and direct the light like it is on a tripod. Way better than a flat ceiling bounce!
It does tail stand beautifully for an angle light, and laid down you’re right about the versatility in aiming it. The clip you mention isn’t available anymore, but I’m going to check some of my older Fenix lights and see if there’s a match, out of curiosity.
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WalkIntoTheLight
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SKV89 wrote:
I tried a few Zebralights in the past because they are supposed to have some of the most efficient drivers. I realize I don’t like their UI at all but I can accept it since I’ve been EDCing Clemence’s Tiara Pros that have a similar UI. However, what I CANNOT get myself to accept is the bad tint. Greenish Cree emitters and tint shift.

Yeah, Zebralight used to suffer from the “tint lottery” with green and yellow tints in the past. I think they’ve finally solved that. My last 4 Zebras have fantastic tints with very little or no shift. If you get a light with the XHP35 HI emitter, like the SC64w HI or SC600w HI, it’s extremely nice with zero tint shift. I can’t tell the SC64w HI apart from a Nichia 219B light, except that it’s only 80 CRI.

I don’t think I’ve ever got a real dud, but my SC52 and SC52w (6 years ago) definitely suffer from the poor XML tints. Though most of my other (non Zebra) XML lights do as well, including modern lights with the domed Cree emitters.

BlueSwordM
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One big advantange of 21700s is their higher gravimetric energy densities afforded by their higher volume/surface area ratio of active materials.

On the more exotic sides, 21700s from Tesla use an aluminium casing, which makes their cells quite a bit lighter, and even more energy dense, while costing less due to using a cheaper electrochemistry.

Even then, their cells have an energy density of 275Wh/kg, and using a capacity optimized 21700 rather than cost/performance optimized 21700 design, probably get close to 300Wh/kg.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

WojtekimbieR
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I see two areas that 21700 changed:

1. Multi-cell lights benefit from higher energy density regardless of single cell's dimensions

2. 26650 are pretty much obsolete

What 21700 won't do is replace 18650 in compact edc lights, as several people have already commented.

Just for a moment... Okay I may stay a little longer

Ventsi
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I refuse to buy any 21700 light for now.
For me 18650 is enough. Flashlights nowadays have 1000-1500 lumens on turbo, which honestly I don’t use all the time because it hurts my eyes. So in reality I get 2+ hours of light on a full battery. Why would I want to use my EDC light for more than 2 hours anyway? And if it’s some emergency I can always switch to lower mode and use it for a few hours.
I can never utilize the capacity of a 21700 battery and it seems useless for me to carry the weight and size around.
For EDC I would say even 14500/16340 are better. I only carry 18650 lights if I KNOW I’m gonna use it at some point.

Jack Kellar
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18650 is my go-to size, and honestly I am constantly surprised by how small the lights are (I’m a big guy). That said, what I like most in them is the comfort of having 500+ lumens for a while under regulation, even though it takes weeks before I need to give my cells a jolt, moreso now that it’s nearing summer and the sun is dawning at 4-ish AM already.

I think I’d adapt well to 21700 lights if it ever came to it. Moreso because unless I’m DEAD wrong, 21700 torches can take 18650 cells with the correct spacing. Big plus for me on that.

cabfrank
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I’m settled and happy with 18650’s and have been for a while. I think the size is good, I don’t want bigger, and the capacity is plenty. I would rather see more 3500mah, or more if that becomes possible, 18650’s than I would more 21700’s. I really don’t want to get into new, bigger lights, and a new size of cells.

WalkIntoTheLight
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Jack Kellar wrote:
Moreso because unless I’m DEAD wrong, 21700 torches can take 18650 cells with the correct spacing. Big plus for me on that.

Kind of. They need a spacer + a metal extension. Banggood sells something that works: it’s just a small plastic tube with an aluminum cap embedded in the end, which you fit over the negative end of an 18650. Pricey for what it is, though. Cheaper to just buy a 21700 cell.

Another thing I hate about 21700 cells is that it’s really difficult to fit them in chargers. The charger manufacturers haven’t really caught up to it, yet.

riffraff
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Samsung 30T 21700 cells (3000mAh, 35A) fit fine in the Nitecore Q2.

Macka17
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I find a 18650 is ideal for pocket.
Shorts not skin tight jeans. We live in tropics. Usually a light shirt on top.
With a 26650 cell torch for walkabout.
They’re better, with a more comfortable grip for long term hold. Plus more capacity.
and it don’t hurt to carry a spare 18650/26650 in pocket.
They’re not really, going to weigh you down unless you’re a real wimp.

I like to carry a backup in case the one I’m using plays up.
Plus. Twice the range.
Often I go with my headlight. Dual 18650 in band. with 26650 in hand for throw.
Purrfect.

Take one light. (for lightness?) 3 miles from home on tracks on Moonless night. LED, battery, or driver drop out.
NO spare.

Hmmmm. Have fun.

I’m an old sailor.
Everything I carry, outside the front door.
Has a backup.

delusional
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I disagree. 21700 is not the future.

Solid State batteries are the future.

Furthermore, there will be commercial products available in the year Twenty Twenty.
I’ll bet you Twenty Quatloos!

Woke up to this one day…

Good morning OCF&BD,
I’ve created a new disorder for you. OCF&BD
Obsessive Compulsive Flashlight & Battery Disorder – and of course, there is no known cure, because you keep recharging yourself.

strayz
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I ave been a 18650 fan for a really long time.. I have recently started carrying lights that use AA or 14500’s for size alone. The Lumintop Tool AA 2.0 have found the way in to the pocket. I have had to adjust my pockets since getting moved in to a manager position requiring professional office attire. Smaller knive, light, pocket tool, ect. The only thing that I have not swapped out for a smaller version is my phone.

While I like the idea of the 21700 not sure if I will ever be a convert.

MtnDon
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I like the 21700 in my Wuben TO50R, but that is not an ADC light to me. My prefered EDC size is about the size of the discontinued Olight S15 and S15R, using AA or 14500 cells or up to the size and weight of the FW3A. The MH20 Nitecore is doable. A 21700 will never be my EDC. It is good to have choices to match our personal preferences, though.

xevious
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delusional wrote:
I disagree. 21700 is not the future.

Solid State batteries are the future.

Furthermore, there will be commercial products available in the year Twenty Twenty.
I’ll bet you Twenty Quatloos!

40 Quatloos that the 18650 is revisited with improved chemistry, due to widespread use and compatibility with existing device & component designs.
Scallywag
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I’m definitely interested in 21700 lights for certain things. But I’m 95% certain I’ll never EDC one due to size. I won’t EDC 26650 either. The 30T sure looks fun for hot-rodding.

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Own a Zebralight, great light but the tint is like as Howard Stern would say……………….
Butterface

Still puts out really great though………..:)

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21700 cells are just a form factor.

Cylindrical cells can supports all kinds of builds and chemistries, so 21700s could be using a solid state electrolyte.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Valynor
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What I am kind of waiting/hoping for is a Zebralight "SC70d", basically an as-small-as-can-be 21700 flashlight (scaled up SC64 model for 21700 cell use). With a 90+ CRI LED, of course Smile

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General Motors just announced partnering with LG for new plant. Wonder what size they will use.

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Pouches

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An interesting 2018 technical article in the Journal of the Electrochemical Society, comparing 21700 to 18650:

http://jes.ecsdl.org/content/165/14/A3284.full

Some excerpts:

Quote:
…Currently, a few different types of 20700 and 21700 cells are available commercially, however, to best of our knowledge there are no published scientific investigations on these cells. Furthermore, in different discussions, we found that there is a controversy on an increase of energy density by the cell format and a need to clarify this topic on a scientific basis. Therefore, in this work we wish to shed some light on the new format and its potential impact. To do this, we compared several commercial 18650, 20700, and 21700 cells (see Table I).

…The energy content per cell can be higher by ∼50% for 21700 compared to 18650. Therefore, for certain applications, less cells have to be built and used to deliver the same amount of energy.

…The higher energy content on cell level leads to potentially lower effort and costs in the production of 21700 compared to 18650 type cells and their packs. The benefit of lower cell hardware costs is likely to be caused mainly by less cell housings, fewer jellyroll insertions/closings/tab welding, and less cell formations per Wh. More produced Wh per existing station might also have a trickledown effect on the cost.

…The energy density does not increase significantly by changing the cell format from 18650 to 21700 type. Instead, for state-of-the-art cells, the energy density is mainly a function of the anode coating thickness, i.e. high energy cells with current material combinations usually have thicker electrodes. The study showed that it is very important to use comparable coating thicknesses or electrode loadings when comparing different active materials or at least give the coating thickness for later comparison.

…The cell resistance is negatively influenced by the electrode thickness and positively by the electrode area. For cylindrical cells these parameters correlate with each other. This contributes to the lower performance of high energy cells. Going from the 18650 to the 21700 format, the cell resistance decreases noticeably and shows a relatively flatter correlation to anode coating thickness. The reason is the larger usable coated cathode area in the larger 21700-type cells, especially due to the outer windings of the jelly roll.

…Increasing electrode thickness in commercial cells has a negative impact on the discharge rate capability. Cells with thicker electrodes experience higher losses by limited transport, resulting in lower discharge energy and underutilized electrode active material. The general trend for all tested cell types was found that the rate-capability is limited by the temperature on the cell surface due to current flow.

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I have two 21700 lights. A C8F and a FF E07. The C8F isn’t pocketable at all to me, heads too big. The E07 I can pull off occasionally depending on what britches I am wearing. Colder weather and it’s Levi’s 501’s. The E07 isn’t fitting in that pocket without it being quite unpleasant to carry. I am most often working or running around after dark. I appreciate the run time of a 18650. Even then it has to be a fairly small 18650. Zebralight or DQG mostly. Most tube lights are too long for my liking.

I carry 18350 lights a lot as well. Armytek, Jetbeam, Reylight or a shorty S2+. Don’t carry AA\14500 much. SC52w or Reylight if I do.

Weight isn’t really a issue for me. I am a decent sized fella. 6’1” and 230lbs. I always carry a full sized, steel framed pistol concealed inside the waist band in a quality holster. If I can make that disappear and not notice the weight of it much, I highly doubt I will complain about flashlight weight. What I don’t like is things hanging around in holsters, on belt loops, or otherwise outside of my pockets or waistband. Too many things to snag me up on my day to day activities.

Is 21700 the future? For some things I’m sure they are. For flashlights? Not so much. I mean it’s not really the future, they are already here. It’s just an option available if you need it. Some do, some don’t. When 18650’s came out I’m sure someone tried to make the same observation. Yet we still have 10180, 14500, 16340, 18350 etc…… Sorry if I missed your favorite in between or oddball size. Point is they all still exist and are still made today even though at one time, 18650 was the future. They are even making better quality, higher capacity and higher current versions of those cells than they have ever made in the past.

So even the old cells still have a future. We are just at the end of a very long line of users for these cells. If battery manufactures had to depend on the flashlight folks to make their livings, they would die of hunger before the end of the first quarter.

"Everywhere I go, there I am"

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if 18650 battery suddenly will stop production then i can see the 21700 taking over, otherwise maybe not idk ??

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WalkIntoTheLight wrote:

………………..

Another thing I hate about 21700 cells is that it’s really difficult to fit them in chargers. The charger manufacturers haven’t really caught up to it, yet.


To recharge the 21700 I use my old chargers, Trustfire TR-005 and TR-006, they take 73mm long batteries. I’m waiting for other more modern chargers but for now I use these

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