18650, 21700, 16650 -- How much do you really want?

DoctorMemory

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Many makers of 18650-based lights are coming out with new 21700-based versions. Why not, look at the increased run-times, the turbo lumens? How can you go wrong, gotta keep current.

But does everyone really want to carry around a 21700 light? It's bigger and heavier. Is it the best compromise in size vs. capabilities?

Some people carry an 18350 light, or a 14500 light, the 18650 is more than they want to haul around in their pocket, their toolbelt.

What makes me think about this is my Quark MKIII light with a 16650 cell. I have so many lights to pick when I grab one, and I see to like this size the most. Just a bit thinner, but it feels better, at least to me.

So who wants to have a 21700 everywhere, even their headlamps? Or all the way to a 14500?
 
Lynx_Arc

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I'm fine with 18650s for now....... 21700s you aren't gaining increased power density going to it for the increase in volume and going larger or smaller than those two sizes loses you power density considerable enough that multiple 18650s or 21700s are better (for now) than 26650 etc sizes.
I was considering 18350 but a lot lower power density nixed that idea and 14500s are only about 20% more power than an eneloop pro if you can get by with the lower voltage.

I don't think a single 21700 cell headlamp is in my thinking the larger volume and weight in exchange for higher capacity and output isn't worth it. I would consider a 21700 flashlight and other devices if it were not for having an excess of 18650s already. One other thing to consider is you need higher charging rates to match the time it takes to charge and 18650 if the 21700 is about 50% more capacity at around 5000mah vs 3400mah 18650s this equates to needing 50% more current on your charger to catch up.

I think that folks who are not already invested in 18650 may consider 21700s but often choosing that format equates higher costs overall and for me the 18650 format is more than enough and if I need more power I can take an extra cell.
 
tech25

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18650 sized lights in general is pushing what I will carry everyday. However for a light that’s meant for more power that goes in a jacket pocket or backpack I prefer the 21700 for more runtime.
I currently carry a 16340 moving up to an 18500 (HDS) for runtime.
(I do realize that an 18500 HDS is probably going to be bigger than an 18650 Zebralight but I like the rotary UI too much to switch)

As far as headlamps, I used to carry a ZL AA but upgraded to an 18650 version for the added power and runtime. I find that the bigger headlamp gets taken with me less often than I used to carry the smaller version. If they come out with an in between size I would be all over it.

Basically, for my edc I want good runtimes and smaller size. Depending on the circumstances, I carry an extra light/s.

Currently my extra battery for my HDS is carried in a PK-PR1, which is not carried all of the time. At night I add another light from a rotating selection and in my pack is a headlamp and a thrower.
 
D

Duster1671

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I am a little jaded when it comes to battery tech. I have lights that take 14500, 16340, 16650, 18350, 18650, and 26650. Numerous cells of each size. It's already too much.

I would need to find a light really compelling to break into yet another battery size. Nothing I've seen in the 21700 size clears that bar.
 
C

chip100t

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I have many lights that take 21700 but mainly carry 18650 lights. And in places where I want to stash and forget lights for just in case I use cr123a primaries.
 
Lynx_Arc

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The only other lithium ion cell that is in the same power density category is the upcoming 46800 and the problem with it is the size is too big for many flashlight things and an odd size for lanterns.... perhaps a single cell for a small lantern would be a good thing maybe soup can lights and power banks but not really headlamps or flashlights.
 
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3_gun

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Most of what I EDC are 18650 & 21700 formats. Had been a 14500/AA guy for years but needs/use changed. Still carry the smaller format lights but those days are fewer now.
 
idleprocess

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But does everyone really want to carry around a 21700 light?
No. But I also don't want to routinely pants pocket carry an 18650 light, so the 21700's appreciable bump in capabilities for a miniscule bump in girth and a slight increase in length isn't really a big ask in exchange for appreciably more energy and power.

Not that I've made the jump. But I sense it coming.

The only other lithium ion cell that is in the same power density category is the upcoming 46800 and the problem with it is the size is too big for many flashlight things and an odd size for lanterns....
Seems like a great cell for beer can formfactor lights.

...

Here's a quick visualization of the cells using nominal dimensions; 18650 red, 21700 green, 4680 blue:
1642125538422

A 21700 light Should Be™ 3mm/16.7% greater in diameter and 5mm/7.7% greater in length. For my purposes that's not much of an increase and thus suitable for task-centric pocket carry or slipping into a bag - be it a backpack or a toolbag.

The jump to 4680 is clearly immense, however it's probably not going to stand in for single cells. Here's a 4680 relative to 4 18650s in a 2x2 array for the beer can formfactor:
1642125607655

A 4680 is more like a jumbo D cell. Here the 4680 is ~2.54mm / 5.5% larger in diameter while being 15mm / 23% longer than a 2x2 array of 18650s. The length increase is appreciable, but in exchange for that you should get something like 78.6% more energy since a high-density 4680 is likely to hit ~25Ah relative to the 4 x 3.5Ah = 14 Ah of four 18650s.
 
H

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Pocket carry, I prefer 16650 for my Fenix PD30 R4. Also like 1 AAA (Fenix EO1 v.2, Olight i3e EOS), or small built in battery lights (Nitecore Tip, Tip CRI, Tip 2). Headlights, I prefer no larger than 18650 (Nitecore HC60 v.2). For shorter trips, 14500 works well (Acebeam H40). My favorite, if I can get away with using it, is a Nitecore NU20. I haven’t seen anything better for lightweight and comfort. For belt carry, I like 21700 (Nitecore E4K), but that light will fit in a pocket.
 
Lynx_Arc

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No. But I also don't want to routinely pants pocket carry an 18650 light, so the 21700's appreciable bump in capabilities for a miniscule bump in girth and a slight increase in length isn't really a big ask in exchange for appreciably more energy and power.

Not that I've made the jump. But I sense it coming.


Seems like a great cell for beer can formfactor lights.

...

Here's a quick visualization of the cells using nominal dimensions; 18650 red, 21700 green, 4680 blue:
View attachment 22330
A 21700 light Should Be™ 3mm/16.7% greater in diameter and 5mm/7.7% greater in length. For my purposes that's not much of an increase and thus suitable for task-centric pocket carry or slipping into a bag - be it a backpack or a toolbag.

The jump to 4680 is clearly immense, however it's probably not going to stand in for single cells. Here's a 4680 relative to 4 18650s in a 2x2 array for the beer can formfactor:
View attachment 22331
A 4680 is more like a jumbo D cell. Here the 4680 is ~2.54mm / 5.5% larger in diameter while being 15mm / 23% longer than a 2x2 array of 18650s. The length increase is appreciable, but in exchange for that you should get something like 78.6% more energy since a high-density 4680 is likely to hit ~25Ah relative to the 4 x 3.5Ah = 14 Ah of four 18650s.
If you look up the size of the old 6v lantern battery with spring top on it the 4680 is smaller by far but not half the size so if you were considering using a couple of them in a host for some reason you propbably could only get one of them in it. I have a couple of small 18650 lanterns taking a single cell and while they do well there is noticeable output limits on it and run times but the lantern because of heat sinking and LEDs is a little larger than the size of a 46800. I think a lantern using one could be around the size of a 3D LED lantern perhaps like the Rayovac ones that used to be popular.
My issue with the 46800 is you really need a protection circuit on it as it likely if shorted out can turn into a huge bomb for sure way more powerful than an 18650 or 21700 and thus more dangerous for sure.
I think these batteries would be ideal for hand held spotlights you could truly crank up the lumens a huge amount.
 
JimIslander

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18650 works well for me at work. Need a light that can blast a beam but also work up close for hours at a time. Flashlight fits my pocket well, and is as much as I ever want on my headlamp.
 
ekardscribner73

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It's hard for me to imagine a better balance of size and power than the 18650. It's also hard to imagine needing more than 3500mAh in a pocket. If the light doesn't go in a pocket, then the size is less of an issue. But then if you have other 18650 lights already, it's convenient to use the same fleet of batteries for everything rather than maintain multiple sizes.

ETA I say that but then I'll probably end up buying 18500s for occasional use in Malkoff MD3 lights...
 
P

pnwoutdoors

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The way I use flashlights, I have two distinct areas of use: on me, as an everyday carried unit; and off me, as with lights in the car or at home. I'm willing to have, say, 18650 or smaller for the carried light(s), but am willing to go a bit larger to get increased run times, for in-place (vehicle or home) units.

At the moment, all of my lights are of the same format: SolarForce or LumensFactory tube, Malkoff LED @ ~400 lumens, and a 1x18650 cell; basically, SureFire 6P sized. For the car and home lights, I'd consider going to a 2x21700 cell and an LED module with 1.5x to 2x the output. But for daily-carried lights, I'll stick with a max size of the 6P format. Plenty large for me.

For a single light using the same LED and same battery, I find the 6P-sized light to be a good compromise between output, duration, heft and size. Enough output for defensive use, close-quarters use (ie, digging around in the HVAC or car), with enough heft and size to be a modest defensive tool if need be, yet (with the Malkoff potted LED) sufficiently durable to withstand normal "bumps and bruises" of daily-carried and -used lights.
 
bykfixer

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I don't typically need the light of a flashlight for very long. I understand the value of the 21mm cell and will probably add one some day.
If my career involved more uses or longer periods of use I'd probably be all warm and fuzzy about these new cells. But since about 300 lumens is usually plenty and it's mainly a hobby I just set on the sidelines, letting things shake out while enjoying the virtues of 2016 technology.
 
kreisl

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even in distant future i woht go bigger than 18650 . it is interesting tho that even Zebralight and Fenis (i.e. the most conservative and slowest companies) have some 21700 lights in the catalog . personally , i am boicotting those models .

L-headlamps with 21700? lmao
 
Olumin

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Up to 18650 for single cell lights, 21700s for anything larger.
Once you go two cells & up there is no advantage to 18650s. On top of that 21s in series will have a bigger diameter tube that is ergonomically nicer to hold, but still a little off from my preferred 30mm (C-cell lights).
 
N

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It's usually never a need, anymore. I have a Fivemega 1x26650 E-head with a KX2 bezel on it, and a FM 2x26650 C-head with an M91W in a Z44. Both of them feel just a mite large for me, but I'm keeping them (and all of my FM products). About the only 21700 lights I would be interested in right now would be a 21700 version of the aforementioned Fivemega bodies - both in a tailstanding version, please! I would have to buy a new charger since I don't currently have any 21700 cells. I have an aversion to soda can lights, but there is room for everyone at the table.
 
idleprocess

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If you look up the size of the old 6v lantern battery with spring top on it the 4680 is smaller by far but not half the size so if you were considering using a couple of them in a host for some reason you propbably could only get one of them in it.
~90 watt-hours in a lantern can produce a lot of light for a long time, a little light for days, or a heck of a lot of light for a couple hours. I think being limited to one cell isn't going to be a problem.

My issue with the 46800 is you really need a protection circuit on it as it likely if shorted out can turn into a huge bomb for sure way more powerful than an 18650 or 21700 and thus more dangerous for sure.
I'm fine with that. Even limiting discharge current to C is a heck of lot of amps.
 
Lynx_Arc

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~90 watt-hours in a lantern can produce a lot of light for a long time, a little light for days, or a heck of a lot of light for a couple hours. I think being limited to one cell isn't going to be a problem.


I'm fine with that. Even limiting discharge current to C is a heck of lot of amps.
All in all I think this size won't be easily adaptable to existing devices it will take a new size of device to properly house it. But considering the size and capacity a single cell non removable rechargeable lantern or bluetooth speaker or whatever would be intriguing for sure. One device I think would be cool is a desk lantern combo power bank as 25Ah is a huge amount. Perhaps a car battery replacement using a dozen of these to make for 100Ah. I think overall the price and power density and cost per watt hour would be the main consideration for battery packs as industry is well used to scads of 18650s in a brick to power everything these days so unless the 4680 offers higher power density or huge current outputs is needed current 18650 and 21700 packs would suffice already.
 

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