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

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Couchmaster
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I don’t think most of you are realizing whats occurring here. It is a sea change which will upend whats going on with something entirely different. It’s not that this new 21700 cell is a different size or even better. It is going to change the world. Not because it is a 21700 instead of a 18650 and size matters (ask my wife- wait, nevermind). They will be powering battery banks for houses and factories the same way that the 18650 are powering some cordless tools today. Solar arrays will be charging these battery banks all day and at night you will be able to run your home and recharge your car (same cells) off them. It isn’t just Tesla that will have them. Every EV car and E device will as well. Not just because of size. That Tesla says this is the optimum size is critical to industry acceptance, but because the future will see X3 the power and then later even more, from that size cell. There are multiple streams of R&D working to make them better, along with every major mfg of energy will be working on making them better. To last longer and pump out more power. Faster better quicker. This is huge like we haven’t seen since Edison started to wire cities for electricity. 21700 is the future, as sure as the sun will shine tomorrow. But isn’t not 5000 mah that is in question, but if 10,000 will be there sooner than we can conceive. It ain’t about flashlights. It’s about the world.

Please don’t ask me for a timeline. If the middle east crashes tomorrow, I’d say “sooner’ If they find another Bakken, I’d say “Later, much later”. It’s coming, and in a big way.

Enderman
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Couchmaster wrote:
I don’t think most of you are realizing whats occurring here. It is a sea change which will upend whats going on with something entirely different. It’s not that this new 21700 cell is a different size or even better. It is going to change the world. Not because it is a 21700 instead of a 18650 and size matters (ask my wife- wait, nevermind). They will be powering battery banks for houses and factories the same way that the 18650 are powering some cordless tools today. Solar arrays will be charging these battery banks all day and at night you will be able to run your home and recharge your car (same cells) off them. It isn’t just Tesla that will have them. Every EV car and E device will as well. Not just because of size. That Tesla says this is the optimum size is critical to industry acceptance, but because the future will see X3 the power and then later even more, from that size cell. There are multiple streams of R&D working to make them better, along with every major mfg of energy will be working on making them better. To last longer and pump out more power. Faster better quicker. This is huge like we haven’t seen since Edison started to wire cities for electricity. 21700 is the future, as sure as the sun will shine tomorrow. But isn’t not 5000 mah that is in question, but if 10,000 will be there sooner than we can conceive. It ain’t about flashlights. It’s about the world.
Please don’t ask me for a timeline. If the middle east crashes tomorrow, I’d say “sooner’ If they find another Bakken, I’d say “Later, much later”. It’s coming, and in a big way.

Battery banks for houses use SLA batteries because it is much cheaper for larger capacities.
Batteries for EVs are made from LiFePO4 prismatic cells which have far more charge cycles and more stable voltage curve. They also take up less space than cylindrical cells.
I contacted battery manufacturers for EVs and they have stopped producing more of their large scale cylindrical cells in favour of prismatic.
21700 will never become popular outside of tesla vehicles.
poster
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don’t Li-ion have higher energy density then LiFePO4

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Couchmaster wrote:
I don’t think most of you are realizing whats occurring here. It is a sea change which will upend whats going on with something entirely different. It’s not that this new 21700 cell is a different size or even better. It is going to change the world. Not because it is a 21700 instead of a 18650 and size matters (ask my wife- wait, nevermind). They will be powering battery banks for houses and factories the same way that the 18650 are powering some cordless tools today. Solar arrays will be charging these battery banks all day and at night you will be able to run your home and recharge your car (same cells) off them. It isn’t just Tesla that will have them. Every EV car and E device will as well. Not just because of size. That Tesla says this is the optimum size is critical to industry acceptance, but because the future will see X3 the power and then later even more, from that size cell. There are multiple streams of R&D working to make them better, along with every major mfg of energy will be working on making them better. To last longer and pump out more power. Faster better quicker. This is huge like we haven’t seen since Edison started to wire cities for electricity. 21700 is the future, as sure as the sun will shine tomorrow. But isn’t not 5000 mah that is in question, but if 10,000 will be there sooner than we can conceive. It ain’t about flashlights. It’s about the world.

Please don’t ask me for a timeline. If the middle east crashes tomorrow, I’d say “sooner’ If they find another Bakken, I’d say “Later, much later”. It’s coming, and in a big way.

Very interesting assessment ‘Couchmaster’.
You may very well be on to something, what you say makes a lot of sense. Thumbs Up

One thing is certain…. time will tell. Wink

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Couchmaster
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The chemistry might in fact turn out to be something entirely new. There are a lot of companies, not just Tesla, tossing large money and a lot of high quality personal at the problem of optimizing power storage in these cells. Tesla was in a race to get product finalized as the development of the batteries was about to head on crash in a race with the development of the gigafactory. They didn’t just try to change the form, but the function as well. They were still testing new cathode material a few weeks before the production was to start I had heard. I suspect that the product they are producing now will be tweaked, modified and improved on a continual basis. I’d love to see a Tesla engineer/chemist share how that went down.

But the Obama administration has also placed a lot of bets on energy via grants. I don’t know what the next administration intends as far as those go but would expect a lot of continuation. I doubt there is a comprehensive list anywhere in the world of everyone who is working on this issue.

Enderman
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poster wrote:
don’t Li-ion have higher energy density then LiFePO4

Yes, but only last hundreds of cycles compared to thousands for lifepo4.

For something used as often as a vehicle it is nice to not have to spend $5000 on a new battery every few years.

SubLGT
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Some test results, at 20A, 30A, and 35A, for the Samsung INR21700-30T can be found here:

http://www.mountainprophet.de/forum/viewtopic.php?f=16&t=952&sid=2cc2ee9...

In this mini test, it was compared to a Sony 18650 VTC5A and a Sanyo 20700B.

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SubLGT wrote:
Some test results, at 20A, 30A, and 35A, for the Samsung INR21700-30T can be found here:

http://www.mountainprophet.de/forum/viewtopic.php?f=16&t=952&sid=2cc2ee9...

In this mini test, it was compared to a Sony 18650 VTC5A and a Sanyo 20700B.

HKJ has posted his more thorough test of the Samsung INR21700-30T:
http://budgetlightforum.com/node/53534

An impressive battery at high currents.

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The thing is it is not just a size game, 26650 never got the attention it need from manufacturer hence it relatively low capability, in theory it should perform much better in capacity and amp draws compared to 18650 but look how much more capacity we gained from 26650? The new Sony 21700 3Tron should be around 5000mah that is as big as 26650 capacity-wise why? because that is where manufacturer now put their research/effort on. So if they leave the 18650 and focus on 21700 i think it is in our best interest that we also starting to use 21700 as a 18650 replacement. As the development on 18650 will be secondary.

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rizky_p wrote:
i think it is in our best interest that we also starting to use 21700 as a 18650 replacement. As the development on 18650 will be secondary.

Springs can take up the 5mm slack along the longitudinal axis, and all anyone needs to do is make battery-tubes bigger by 3mm (1.5mm “wrap” would take care of rattling 18650s).

The same way a tube that takes an 18350 can also accommodate 16340s with a little slop, the same can be done for 18650s vs 20700s/21700s.

Don’t want rattles, a bit of construction-paper wrapped around an 18650 can cure that.

Don’t see what the problem is, just need flashlight mfrs to get on board.

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rizky_p wrote:
The thing is it is not just a size game, 26650 never got the attention it need from manufacturer hence it relatively low capability, in theory it should perform much better in capacity and amp draws compared to 18650 but look how much more capacity we gained from 26650? The new Sony 21700 3Tron should be around 5000mah that is as big as 26650 capacity-wise why? because that is where manufacturer now put their research/effort on. So if they leave the 18650 and focus on 21700 i think it is in our best interest that we also starting to use 21700 as a 18650 replacement. As the development on 18650 will be secondary.

Assuming it’s true, it’s still not as high capacity as 26650 (5500 mAh Shockli), but is nevertheless more efficient on per-volume basis. On par with 18650. And really looks like a great choice for pocket rockets.
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gauss163 wrote:
Enderman wrote:
[Li-ion] only last hundreds of cycles compared to thousands for lifepo4.

Not necessarily. Well-designed Li-ion battery systems can yield thousands of cycles, e.g. below is some real-world Tesla Model S cycle-life data reported by Tesla owners, from Maarten Steinbuch’s blog.


You do realize that this graph still shows “hundreds” of cycles, not “thousands” right? Wink

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Somebody mentioned flashlights that come with 3×AAA adapters. They are a bit larger than 18650, aren't they? Would 21700 fit? 

Personally, I prefer 26650 size over the thinner 18650. If large efforts are put into developing 21700 cells with >4500mAh, then those would be better than 26650 in every way. This is what I hope will happen

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

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The formula for fitting 3 small circles with diameter d in a bigger circle with diameter D is: D = d * (1 + 2/√3).
Or to put it in plain numbers: D = d * 2.1547.
Because the diameter of an AAA cell is 10.5mm, you need 22.62mm for an AAA adapter to fit in.
That should be enough for a 21700 to fit in.

You are a flashaholic if you are forced to come out of the closet, to make room for more flashlights.

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DavidEF wrote:
gauss163 wrote:
Enderman wrote:
[Li-ion] only last hundreds of cycles compared to thousands for lifepo4.

Not necessarily. Well-designed Li-ion battery systems can yield thousands of cycles, e.g. below is some real-world Tesla Model S cycle-life data reported by Tesla owners, from Maarten Steinbuch’s blog.


You do realize that this graph still shows “hundreds” of cycles, not “thousands” right? Wink

Yes, but they will obviously last that long since they have retained so much of their capacity after hundreds of cycles. Even the worst one is still above 85%!
The main thing that makes a difference is not fully charging them and not discharging them all the way to 0%. The other thing is the active cooling. They never get hot.

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Henk4U2 wrote:
The formula for fitting 3 small circles with diameter d in a bigger circle with diameter D is: D = d * (1 + 2/√3).
Or to put it in plain numbers: D = d * 2.1547.
Because the diameter of an AAA cell is 10.5mm, you need 22.62mm for an AAA adapter to fit in.
That should be enough for a 21700 to fit in.

But AAA is 26 mm too short, which adds problems of its own. Nevertheless, good call with 3xAAA.
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Agro wrote:
Henk4U2 wrote:
The formula for fitting 3 small circles with diameter d in a bigger circle with diameter D is: D = d * (1 + 2/√3). Or to put it in plain numbers: D = d * 2.1547. Because the diameter of an AAA cell is 10.5mm, you need 22.62mm for an AAA adapter to fit in. That should be enough for a 21700 to fit in.
But AAA is 26 mm too short, which adds problems of its own. Nevertheless, good call with 3xAAA.

The AAA carrier makes up the difference in length. I have several lights that take AAA or an 18650. They should also work fine with a 21700.

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Couchmaster wrote:
Please don’t ask me for a timeline. If the middle east crashes tomorrow, I’d say “sooner’ If they find another Bakken, I’d say “Later, much later”. It’s coming, and in a big way.

Crap, they found it (the new Bakken) just before I’d posted that upthread! 2nd largest oil field in the world behind the massive Gahwar field in Saudi Arabia. Just found it in Texas no less! “http://www.kalb.com/content/news/Huge-new-oil-and-gas-find-in-west-Texas...

Suspect that will both secure the US as a dominate oil supplier for many years, and slow the rapid acceptance of battery powered cars. How much it slows it remains to be seen, The new Tesla model 3 has like 400,000 some odd pre-orders it’s been said.

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Great find!

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Thanks! I’ve needed a 21700 to check tune sizing on my scratch build, ordered 2 of those. 4.8Ah is not too bad for the 21700 form factor! Even if it is a ~10A max continuous discharge.

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Heh-heh, we got the same email… Big Smile

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21700 is the future IMHO. Small increase in size for big gains in everything else.

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Indeed. Volumetric efficiency (power/size, capacity/size) seems slightly lower than that of 18650. I assume it’s temporary, it should be actually a tad higher. But when considering efficiency of the entire flashlight, they are often better already. But the flashlights haven’t arrived yet…I would love to get an Emisar D4 in 21700. Since the head is larger than battery tube, total size increase would be tiny. Battery would have 40% more juice than GA with about the same power.

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Agro wrote:
Indeed. Volumetric efficiency (power/size, capacity/size) seems slightly lower than that of 18650. I assume it’s temporary, it should be actually a tad higher. But when considering efficiency of the entire flashlight, they are often better already. But the flashlights haven’t arrived yet…I would love to get an Emisar D4 in 21700. Since the head is larger than battery tube, total size increase would be tiny. Battery would have 40% more juice than GA with about the same power.

Yeah, they should be reaching ~5500-5800ma according to the data I saw last year. Course they only started making these batteries last year, so they are doing ok for such a short development time so far.

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With continuous discharge max set around 10A and recommended 4.8A for optimum life, I don’t see these being great for flashlights. The testing I’ve seen to date show an immediate drop to 3.7V when under load, by the time our low voltage protection kicks in they’re only giving 2000mAh capacity (in testing)

I-Joy rates a 40A pulse, which means they too won’t do a continuous discharge rate for say, a triple XP-L. Or even a Luminus SBT-70 for that matter, one, all by itself. So I’m not hedging any bets for these Tesla sized cells to take over our world anytime soon. And besides, carrying extra cells would be all the more difficult due to their sheer size factor.

I got the notifications about the new offerings just like y’all did, but opted out as they won’t run my lights built for the big cells. I need 25-30A continuous, not seeing any of these that will do that. (an Efest 20700 will though….)

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Disregard the I-Joys. If you want capacity, 48G will run at nice output (350 mA) for over 13 hours. Often enough for a weekend without carrying spares. According to Mooch, it handles current just like your 20700B does, which is enough for many uses. It may not live forever when overdriven. Oh well…
If you want power, 30T is scheduled for the next year and it’s a good deal more powerful than VTC5A. Or Efest 20700 for this matter.

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The Efest 20700 has given me absolute best numbers in my scratch built triple XHP-50.2, tested against 20700A, 20700B, LiitoKala blue and black 26650’s and even TrustFire 32650’s, as well as 30Q, Sony VT-C6, LG-HE4, HE2, Efest 3000 in 18650’s.

To better the Efest 20700 will, for me, be a new benchmark indeed. Will be looking for that…

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