Will the 21-70 Battery (a.k.a. 21700) Replace 18650?

18650 wont die so fast but they will get cheaper soon. demand is much less after tesla and panasonic opens the new plant wich double to total world capacity of Li ion cells.

Bort you missed the point. Have you bought a flashlight in the last 5-10 years. Let me tell you in 5-10 years if Tesla cells start to become common. Lights might be factory built to take advantage of that along with all the electronic and LED improvements. This will probably look like what happened when 18650’s and 26650’s became stand alone products and not just laptop salvage. The AA’s and CR123A’s are not dead the 18650 will not die over night but a new most manufactured cell size looks like it is just around the corner. Whats going to also happen is another choice on the market. I will make one prediction 26650’s are going to be a dead or very cheap product. If new technology goes into 21700 and the 26650 continues to be made with average Chinese technology. Energy density wise a 3500mah 18650= a 5130mah 21700 that’s pretty much a 26650.

Yet we still have alkaline AAs sold by the millions if not billions a year. You can get about a dozen different chemistries of AAs from NiCad, NiMH, Alkaline, lithium primary, lithium rechargeable, carbon zinc, zinc chloride, nickel zinc, alkaline manganese etc.
Just becasue Tesla is releasing a new form factor it does not mean 18650 is dead, otherwise why would we have so many battery sizes
Believe what you will, i doubt Tesla is ending 18650, they are just building a new size for their EVs.

They’re probably just rewrapped WhateverFire cells in drag. :smiley:

And even so, get a light that takes a 26650, slap on some of those rubberbandy things that “adapt” 18650s for use in 26650 tubes, and you’ll be able to use 21700s in 26650 tubes as well.

By this logic A 26650 should be 7300mAh.
Can you take a guess why not?

Tell us?

I wouldn’t be surprised if it took 5+ years for these cells to hit the open market. Tesla isn’t going to release them for general sale unless they know for sure that they can meet their own internal needs, and that may very well be never. We’ll probably have to wait until someone like Panasonic, Samsung, LG, or Sony start producing them in their own factories. And for that to happen they will need to see a demand for that cell either from Tesla not being able to produce enough in house or some other car maker or industry adopting that cell. The sales from those of us using them for flashlights probably don’t even show up as a blip on their radar.

Ok people… it’s time to start discarding 18650 flashlights. :frowning: :stuck_out_tongue:

Spec sheet here:

Someone needs to get a pair of those to HJK for testing, STAT!

Clif Notes:

Rated capacity: 4000mAh
Minimum cap: 4050mAh
Typical cap: 4250mAh

Impressively little voltage sag under 15A discharge

~2800mAh capacity after 500 8A discharge cycles.

Edit: max dia = 20.35mm

I wonder how many lights out there have enough body material available such that a enterprising modder with a mini lathe could bore the body slightly to fit a 20700…

There is nothing special about them…
They are in between 18650 and 26650 size, and have between 18650 and 26650 capacity.
It’s just a different size battery.
Why bother making an entirely different flashlight just to fit a different battery if you already have two FAR more widespread options that are the same energy density?

It literally makes no sense….
“let’s make a new shoe size that is between 11 and 11.5, and that fits feet between size 11 and 11.5!”
The difference between 18650 and 26650 is just a few millimeters of diameter, and if you want a larger diameter body you go with 26650, if you want less then you go 18650.
There is no benefit to going in between.

If a new type of battery is to be introduced it needs to bring something better to the table than there already is.
Not “lets make something sized in between, that performs in between”

The 26650 is far from the same energy density as the 18650, I bet they are even worse then the 20700.

4000ma in a high discharge cell is 33% more then you get in a 18650, that is well worth taking note of.

26650 lights are ok but they are large and heavy, only suitable to larger format lights. The 20700 could fit in EDC lights.

The problem with the 26650 is that it has a much lower energy density than the 18650.

Now we have a 21700 with the same high energy density as a 18650 but with the potential to have greater discharge rate and capacity than the 18650 (probably on-par with the 26650) but in a much smaller package then the 26650.

Those are advantages which we flashlight dudes can work with to produce lights which are more powerful than those which run on 18650 but smaller than those which run on 26650.

Also, the 1 inch diameter (25.4mm) battery tubes we now use with 18650 can also fit the 21700 - just bore the hole a bit larger.

The only thing is the tailcap thread diameter area will need to be a few mm larger which is no big deal.

Generally speaking, I bet the lights which run on the 26650 now can also run on the 21700 with the same resulting performance.

If you used the same “better manufacturing” used for the tesla batteries then you would have 26650s with the same energy density as 18650s.
Maybe instead of trying to introduce something in the middle just improve what you already have??

But they are not and will not do that. They have had 26650’s for how many years? Yet not a single major manufacture has produced a 26650 yet. Thus I think it is safe to say they will not be doing so.

The 20700 should reach 26650 levels fairly easy with major brands working on them.

Technically Sony did make some 26650s but this proves the point even more, they tried and gave up a long time ago. Not enough buyers probably which is really the only reason this Tesla stuff is interesting, it’s a large enough market push that it could shift production by major battery manufacturers. Then you stack on that these manufacturers are interested in producing as few different cells types as possible to compete with economies of scale. It’s up in the air, some may switch a lot of production and development to these new cells and maybe eventually all of it. I’m sure we’ll always have all the weird sizes we love from Chinese brands as long as there is the demand.

No matter what happens though, I’m excited, it’s a new cell type to build lights around and more money in development of better batteries.

Just say when akkuteile.de or nkon.nl got them in stock and I will order some.
My queue is fairly short at the moment, i.e. a review will probably show up in less than a month.

Thank you HKJ. Hopefully the battery will show up in the European outlets soon.

Here is a test/review:

BMZ, who are building a gigafactory in Europe, have voted for the 21700 over the 18650:

"……….Europe’s biggest battery supplier says, “With 3Tron, BMZ is putting its trust in a completely new format: instead of a 18650 (18mm diameter and 65mm high) cell size, 3Tron will be produced as a size 21700 cell (21mm diameter and 70mm high)…..The 3Tron battery system, as the first 21700 format system worldwide, is setting the standard in this new class – because it is clear that other manufacturers will follow and produce 21700 format batteries as well: the development possibilities of the 18650 cell format are exhausted.”…………."

Sanyo NCR20700A: 3100mAh, 30A, $10/unit
Sanyo NCR20700B: 4000mAh, 15A, $10/unit