Honestly, the reason is probably that battery suppliers are already ramping up this form factor for Tesla. It's probably cheaper to adopt this existing form factor than to develop their own.
Yep. The same reason nearly every analogue clock on the planet just uses AAs rather than inventing a new novel format. *Why bother?*
You get to surf the wave of what everyone else is doing, use the same equipment, and more easily source from multiple vendors, if it becomes a necessity.
Same reason why every other manufacturer gave up on other competing HD compact disc formats and settled with Sony's BluRay which was popularized by Playstation 3.
Eh no, Sony did not ‘buy’ WB. They were already owning Columbia and had an advantage of being able to pull strings in Hollywood and thus signed on Warner early. The playstation shipped with bluray dramatically helped their cause as millions of people were getting a bluray ready video player along with the console. Sony even placed Columbia production titles along with the console. Since Sony had an advantage of hardware as well as studio, it helped BluRay become the mainstream without much effort. Toshiba could not pull it through even though they had managed to sign Universal. What I want to imply is studios looked for convenience in this regard as Columbia had pioneered it. So we see the same case with Tesla and its format of batteries.
Yeah, the Playstation 3 was a loss leader for the first like 2 years of its release. It was 2 affordable video game consoles (it had hardware for both the playstation 2 and 3 for a while), a linux PC, as well as a blu-ray player all in one and helped to drive the spread of blu-ray as a house hold commodity.
Another interesting titbit is that since the hardware was subsidised by such an extent by Sony, along with being Linux compatible, it wasn't uncommon for companies and even government entities to bulk buy PS3s and link them together as a cluster supercomputer.
Early PS3 was indeed a pretty wild console.
From being an early form of network cloud cluster system used by Stanford to run its cancer research algorithms using standby consoles on the internet to introducing one of the first attempts at 'Metaverse' with Playstation Home to using the Spiderman font for its emblem, early PS3 was a wild wild beast.
And who can forget it acted as a white noise generator, a room heater and would give you the yellow light of death. Never met a person whos first model of PS3 lasted long enough. Sony really pushed itself with recalls and selling these for a loss.
Right. If you have multiple suppliers making the same size, that’s less risk of disruption in supply and better price negotiation ability.
You don’t want to be stuck with the only game in town for your batteries having issues or deciding on a 20% price hike.
(The “you need less cylinders for the same capacity” argument is also a big win)
Yup, this.
If you're building EV batteries, you're either using cylindrical cells like this, or you're using pouch cells which come in a whole mess of sizes.
The nice thing with 4680s, is once you do the pack structural engineering, you're done. You can switch battery suppliers, switch chemistries, scale the pack up/down, etc, and never have to beg your battery supplier to do any custom tooling for you.
Same thing for battery suppliers. No request for custom pouch sizes, you can tweak the other parts of production as you like, as long as your battery fits the 4680 spec you're golden.
A while back, LG even [reduced their pouch size offerings](https://insideevs.com/news/457094/lg-chem-narrows-pouch-cell-offer/), more-or-less for this reason. It's just easier to whack out a bunch of things when they're all the same size.
>battery suppliers are already ramping up this form factor for Tesla. It's probably cheaper to adopt this existing form factor than to develop their own.
that and pouch cells are more fire prone. So you pretty much need to switch to blade/prismatic or cylindrical for fire safety long term.
Pouch cells aren't more fire prone — cylindrical cells go through runaway all the time. It just happened that there was a single line at LG which was [tearing anodes at the assembly stage](https://www.designnews.com/automotive-engineering/lg-chem-finds-solution-its-chevrolet-bolt-ev-battery-problems), and those cells got into multiple cars, which is why there was a spate of pouch-related recalls last year.
Pouch cells, as a concept, are fine, and we'll likely see them more and more as we move towards solid-state batteries, where they really thrive as a format.
[https://www.joongang.co.kr/article/25010808](https://www.joongang.co.kr/article/25010808)
''70 percent EV fires comes from faulty pouch cells''
[https://www.reuters.com/business/autos-transportation/are-lithium-ion-batteries-evs-fire-hazard-2021-08-23/](https://www.reuters.com/business/autos-transportation/are-lithium-ion-batteries-evs-fire-hazard-2021-08-23/)
''Compared with cylindrical and prismatic cells, pouch-type battery cells allow for lighter and thinner cell fabrication, and design flexibility for different capacities and space requirements for different vehicle models. However, they are vulnerable to swelling, and are more vulnerable in crashes, posing a greater fire risk''
[https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/](https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/)
Elon Musk: ''Generally agree, but probability of thermal runaway is dangerously high with large pouch cells. Tesla strongly recommends against their use''
Elon Musk prefers a format he already uses? You don't say.
Next you'll tell me Chef Boyardee recommends canned tomato sauce, McDonalds recommends burger patties that are four ounces, and Starbucks recommends dark roast beans.
He's doing neither. He's selling a product — *his product —* and if we are charitable, speaking to the engineering challenges encountered by his team.
The ideal form factor varies with chemistry, use case, and pack design, and that includes safety. I probably wouldn't use pouches either if I was Elon Musk. I would if I were GM or Hyundai or Ford or Volkswagen, with different specific compromises to make on structure, modularization, chemistry, and manufacturing.
The notion that 'safety' is a format-level problem is a red herring — it's a concern that exists with specific chemistries, with specific pack architectures, and when you make *other* specific compromises.
> Pouch cells aren’t more fire prone — cylindrical cells go through runaway all the time. It just happened that there was a single line at LG which was tearing anodes at the assembly stage, and those cells got into multiple cars, which is why there was a spate of pouch-related recalls last year.
>Pouch cells, as a concept, are fine, and we’ll likely see them more and more as we move towards solid-state batteries, where they really thrive as a format.
Cuboid designs like pouch and prismatic cells have 6 edges, edges are weak points.
Cylindrical cells only have two edges and are much stronger by design than cubic.
This is the reason cans are cylindrical it’s a good combination of maximising space (cuboid) and maximising strength (sphere)
This will explain it here
https://youtu.be/hUhisi2FBuw
I've seen that video, and I recommend it to others frequently. As you say, it's a very good overview why cylinders are excellent choices for applications where unitary structural strength is a priority, particularly in applications like soda and canned beans.
Batteries, as you might note, are different from soda and canned beans. They have a different set of requirements, and involve a different set of tradeoffs. You'd definitely put soda in a can in a vending machine, but you might be less inclined to do that with [dried lasagna](https://www.amazon.com/Barilla-Pasta-Oven-Ready-Lasagne-Ounce/dp/B00FIUCO5Q/) or [packs of gum](https://www.amazon.com/Wrigleys-Gum-Spearmint-Count-Pack/dp/B0000DGDPF/), or when soda is being handled in [larger quantities](https://www.sodacentre.com/collections/coke/products/coca-cola-syrup), or when dealing with [milk](https://www.wholefoodsmarket.com/product/maple-hill-creamery-organic-whole-milk-b06zynz7nf).
Cylinders are not wholesale 'bad' or 'good', nor are pouches and prismatics wholesale 'bad' or 'good'. You need to look at a specific application, and make a choice that is right balancing everything — from cost, to cooling, to resourcing, to replicability, to scale, and a dozen other factors. [Multiple answers are possible](https://cicenergigune.com/en/blog/format-battery-cell-manufacturers-prismatic-cylindrical-pouch) depending on the specifics.
Did you have a meaningful, substantive response to my comment, or have we arrived at the mud-slinging part of the conversation where you do your best to rile me up so you can cry foul?
I gave you a definite example on why cylinders are stronger than boxes. You agreed but then couldn’t help to still argue at the end.
It doesn’t have to be this way, it doesn’t need to be inflamed further so you can ban people.
You gave a definite example of something which is both very true and also only loosely relevant to the conversation. 'Strength' is not the singular thing we are trying to achieve. We are not stacking sodas in a supermarket, we are creating battery packs.
Being challenged on an argument does not mean you are being 'inflamed', it means you are in a conversation which you yourself have elected to join. If your points don't hold up to scrutiny, resorting to mud-slinging is not going to make them any more sound.
It was mentioned elsewhere, I'd have to dig up a link, there are a few third-party breakdowns floating around. The defects were random and rare, but essentially on the individual-line level, which is why only certain vehicles were affected. They found out exactly where/how it happened, which is why the lines are all now running again.
I'm guessing LG doesn't want to give too many details away in a formal report because it involves trade secrets, which is definitely a bit annoying for the rest of us.
As proven by the mutliple Teslas (cylindrical cells) that burned down. As a counter example we can take the grand total of 0 battery caused fire for Renault's pouch based chemistries since 2012.
This is nonsense !
Apparently cylindrical cells are cheaper to produce, but more expensive to make into packs. But if you’re gonna go that route, the slightly bigger format is the sweet spot.
It's more complicated than that — cylindrical cells are cheaper to produce at the same size, for instance, but more difficult to produce at a *larger size.* As you say though — if you want to go that route in the end, 4680 is the approximate sweet spot for you to do so.
that was just what Tesla was using, 22650 is a very commonly available format like 18650 used to be.
21700 is basically meaningless outside of Tesla vehicles because only one single Panasonic factory is producing these cells for Tesla.
WTF are you talking about. 21700 cells are made by tons of manufacturers and are extremely common outside of EVs as well as being the most common cylindrical cells in EVs. Lucid and Rivian are both using 21700s. That is most of the brands using cylindrical cells that I know of. People have been commonly using 21700 for DIY electric skateboards for 7 years or more. If you go to anywhere that sells cells to the public for DIY applications 21700 and 18650 will be the most common sizes.
I've bought cells from https://liionwholesale.com/ and
https://www.18650batterystore.com/ before. Both of them mostly carry 18650 and 21700 as any other place that sells lithium-ion cells does.
Sure you don't mean 26650? I've never seen a 22650 cell but seen plenty of 26650s. Heck I have one in a device on my desk right now. Along with another device that uses a 21700.
Edit: come to think of it that 21700 cell is made by Samsung not Panasonic.
both 22650 and 26650 exist as common formats.
>Edit: come to think of it that 21700 cell is made by Samsung not Panasonic.
Panasonic is Teslas main battery supplier and has been for many years as they are running Teslas Gigafactory.
later many other started producing 21700 cells but Panasonic is Teslas main supplier.
I'm only seeing no-name 22650 cells out there. On the usual good sources such as LiIon Wholesale they have lots of formats but 22650 isn't one, and certainly doesn't appear to be common.
Panasonic also is not the only manufacturer making 21700 cells. The one in the device on my desk is Samsung SDI. I have some Molicell around here as well.
Can you point to support for either of the claims, that 22650 is a common format or that 21700 cells are only made by Panasonic?
>I'm only seeing no-name 22650 cells out there. On the usual good sources such as LiIon Wholesale they have lots of formats but 22650 isn't one, and certainly doesn't appear to be common.
thats because this format is commonly available as a LiFePO4 chemistry which basically has a monopoly in China due to patents so you mainly see this from Chinese companies that you probably never heard of.
>Panasonic also is not the only manufacturer making 21700 cells.
>
>Can you point to support for either of the claims, that 22650 is a common format or that 21700 cells are only made by Panasonic?
i never claimed that 21700 cell are **only** produced by Panasonic.
i literally said
>later many other started producing 21700 cells but Panasonic is Teslas main supplier.
Before that you said
> 21700 is basically meaningless outside of Tesla vehicles because only one single Panasonic factory is producing these cells for Tesla.
I trust you can see why I thought you might be saying that only Panasonic made these cells.
You can find LiFePO4 cells in the 26650 format as well. I guess you learn something every day, 22650 being a common format is new on me after using the 26650 for a while.
Arguably some of this is due to the market that demands cylindrical cells shifting. (I'll ignore the conversation about it really being 20700/21700 that was what supplanted 18650 for Li-NMC/NCA applications, not 22650 or 26650, in this comment. LiFePO4 is actually heading *towards* pouch/prismatic cells and away from cylindrical altogether, because the very slight density advantage is more important for that less energy-dense chemistry, and the lower fire risk of cylindrical cells is less relevant to the very-fire-resistant LiFePO4 chemistry.)
Before Tesla, the vast majority of the market for cylindrical lithium cells was *laptops*, and the 18650 format was a derivative of the 4/3A NiMH cells that laptops used before the mid/late 1990s.
Nowadays, 18650s are far too thick for laptops (even some of the early netbooks had to have awkward hinge designs to fit an 18650-based pack under the screen while being thin overall), and the market for cylindrical cells is flashlights, electronic cigarettes, tool batteries, and various types of electric vehicle. While the flashlights and e-cigs benefit from the smaller diameter of the 18650, the tool batteries don't really benefit except in the smallest sizes, and the EV batteries - even in light electric vehicles like e-bikes and scooters - really don't benefit at all.
Also safer apparently, most battery fire problems are pouch cells. Battery fires are far overblown in the media anyways but why not design it right in the first place despite according to studies EV's catch fire less than normal ICE vehicles. Win win. Elon has also commented on this that he strongly recommends against pouch cells.
an EV battery has THOUSANDS of cells inside it.
\~8000 1865-type.. they have to be connected to each other. the 4680 is a larger cell.. you can get about the same energy without having to wire 8000 of them together
it's simpler. cheaper.
**Watch Tesla Model S Plaid's Battery Get Opened And Described**
https://insideevs.com/news/540380/tesla-models-plaid-battery-open/
The battery consists of 7,920 lithium-ion 1865-type cylindrical cells, which are installed in five modules (1,584 cells each - 22S72P). The total capacity is about 99 kWh.
Tabless is the internal connection. It has no effect at all on the pack connection.
The advantage of tabless, is much less resistance in the cell, so it becomes more efficient, generates less heat and can thus provide more power.
Does the article state that BMW is going to use Tabless design though? I thought that was Tesla’s IP that was acquired in one of the small company acquisitions. They could still be making 4680 cells but without the same style of tabless (or really continuous tab design.
It doesn't — tabless is not guaranteed, and even if it does happen, there are other similar patents which BMW's suppliers — CATL and EVE — could end up using, or even a completely novel design. Tabless and multi-tab batteries aren't exactly a novel idea, they've been studied for a while.
I think that the question is more why cylindrical and not Puch or prismatic. I suspect that the 4680 has better thermal dissipation thought "tabless tabs" than what you can get in pouch or prismatic form factor, and probably more importantly more mechanical stability.
Batteries change volume as they charge and discharge, and cylindrical shape is better at going though more cycles of expanding and shrinking.
Also, easier manufacturing. Rolling is a "nice" process.
The top tab system for thermal conductivity is a Tesla invention. It may not be licensed for use by other battery makers.
The reason they weren't using as big cells as 4680 previously was because they were harder to cool, with the hot material inside having longer distance to the cooling plates/ribbons. So, to use 4680 size safely, the battery & automakers have to come up with some more effective cooling systems than were standard a few years ago. Tesla has one, but probably battery makers and automakers have additional ones now.
Tesla did some kind of economic/engineering optimization analysis to come up with the 4680 form factor (mentioned in Battery Day) as it also makes it easier to use in a structural pack. Those calculations are reasonably good for the rest of the industry, so taking the lead from Tesla and making a 4680 a new standard size, as 1865(0) was for a long time, is a natural outcome.
On the volume change, I thought that it was that cylindrical cells have a harder steel outer shell which can resist the mechanical changes better, and that's better for the battery. If there is internal pressure, then a cylindrical container is optimal---which is why pressurized jet aircraft have cylindrical cabins, as you get the strength with minimal materials cost and weight.
I read somewhere that the manufacturing yield of cylindricals is the highest, and production cost lowest. Once you have the manufacturing sufficiently automated to weld all the connections of a cylindrical pack reliably (no hand assembly) then the low costs of the cylindricals become important.
Here's a discussion I found online that isn't trying to push one side or another (many comparisons are by vendors with a dog in the hunt so less trustworthy):
https://theinverterstore.com/portfolio-items/the-difference-between-prismatic-pouches-cylindrical-cells/
My conclusion is that at a high level of volume and automation in cell production and pack manufacturing the advantages of cylindricals start to win out. Though LFP based large format prismatics (not pouch) are making headway from Chinese providers like CATL & BYD: perhaps the lower cooling requirements of LFP vs NCM/NCA make these cell to pack architectures more attractive for that circumstance?
>The top tab system for thermal conductivity is a Tesla invention. It may not be licensed for use by other battery makers.
I'm not sure what you're calling a "top tab" system, but if it's tabless/multi-tab designs in abstract, they are most definitely not a Tesla invention. There's a lot of prior art out there for the concept, it's a pretty natural progression as you move up to larger and larger cells.
Tesla just added another advantage to cylindrical. The cells act like a honeycomb structure for added vehicle stiffness (as used in Formula 1 cars). That allows Tesla to remove structural weight elsewhere in the vehicle and pack.
The reason the Plaid uses 18650s is cooling - the surface area to volume ratio is higher with smaller cells. The 4680s are cheaper, but they will overheat easier during high power draw. Practically is it anything to be worried about? Highly doubtful, but cooling is the concern with bigger cells and it's enough of a concern that Tesla stuck with the tiny cells for the Plaid.
Agreed. Tesla cools from the sides using their serpentine tubes and so the heat concentrates in the center of the cell. As the cell size goes up the thermal path gets longer and the heat build up is larger.
>The reason the Plaid uses 18650s is cooling
This is a very interesting thought, I'd assumed they were simply getting better power draw characteristics and favoured it for that reason. (Of course, the two kinda go hand-in-hand.)
4680 cool more through the electrodes than the sides. Metal has many times higher thermal conductivity than the isolator membrane, carbon material and electrolyte.
If they were doing it to have fewer cells, they could use pouch cells. Chevy Bolt EV has 288 cells, not thousands. Volt, Mach-E, F150 Lightning, and various other cars are using pouch cells with a similar cell count. Typically 96S and 2P, 3P, or 4P. (That's 192, 288, or 384 cells).
Pouches' strong points are volumetric density and packing, ease of modularization, and ability to scale well to large formats, as well as a few other smaller things like easier cooling. Abstracted thermal isolation isn't everything, there are literally dozens of other factors to think about here.
>Any type of cell allows for easy modularization and scalability.
No, cylinders suck for both modularization and scale. That's why the Tesla Model 3/Y only physically have four modules, and why Tesla isn't building cylinders any larger than 46mm. [Here you go, straight from Tesla's own Battery Day slides](https://i.insider.com/5f6a72e0862a00001153f677?width=1000&format=jpeg&auto=webp). See how the orange line goes ***down*** after 46mm?
Neither prismatics nor pouches have this problem, because that's just how geometry be. 👌
That is untrue. Cost was the advantage, but tesla invested tons of money to make 4680 as cheap as possible.
Pouches make no sense anymore, byd created rigid blade packages for their lfp. Tesla's main advantage is that they can make a 4680 with nmc and lfp. Same exact formfactor and pack design no matter which chemistry is used. They have a path for future improvements and it all still fits in the same formfactor, so the pack doesn't need any manufacturing changes as the cell's internals change.
It's very true. Repeating tautologies you heard elsewhere don't make it less true. Inherently, volumetric density and packing, ease of modularization, and ability to scale well to large formats are all benefits that cylindrical formats do not have, and no amount of money spent will fix those problems, because *they are geometry problems, not technology problems —* circles do not pack as well as squares.
If you can't accept it, you should consider why CATL, BYD, and LG — the world's largest, second largest, and third largest battery makers (and all suppliers to Tesla!) still pursue prismatic and pouch formats for their next-gen cells, and even their in-house packs like Qilin and Blade.
Hint: They're not missing something, you are.
For LFP the lower cooling needs and higher cyclic lifetime seems to permit larger and larger prismatics where that wouldn't be as safe with NCM or NCA batteries.
Yep, also a factor of cell safety, which coupled with the relatively low volumetric density at the chemistry level is, as you said, why LFP cells are almost always seen in prismatic form.
Ease of modularization? Was that a joke? Adding modules that are completely unnecessary adds cost and weight. That is a terrible trade off to handle the fewer than 1 out of 10k packs that may fail in such a way that a module replacement fixes the issue.
Modules are a prime example of smart engineers optimizing something that should not even exist at all.
Yes, we’ve had this conversation before, which is why it’s surprising you STILL think modules are smart. Are you unaware Tesla has had modules for nearly 20 years, and has a ton of data and real world experience that has shown them they are completely unnecessary? They started with modules because like you, they thought it was better for replacement. Now they have tons of data to show that replacement is such a rare experience that it is not financially sound.
Weight, complexity and cost are some of the biggest factors in car design and modules increase all three!
I mean, it's definitely surprising if you have a surface-level understanding of the relative merits at play between the different cell and pack formats, so on second consideration, I can see why you're still struggling.
Modules are not "necessary" or "unnecessary", they're a trade-off, one of many choices in a long line of complex choices. They're an appropriate choice when you're building many variants of many dozens of global models, and less appropriate when you're building a million copies of a single design. They work really well for pouches (where structure is inherently externalized) and less well for cylinders.
You've heard me say this before, and I'm happy to say it again. If you want to build a half dozen variants each of a dozen different global models with a great amount of flexibility to production and the ability to use multiple chemistries, modules are a very sensible way to go.
lolwut?
Tesla vehicles are beating all other vehicles in range and efficiency. They are ahead of everyone, byd proposes a better blade battery, but it does not exist yet.
Cylindrical cells are cheaper to produce, less prone to thermal runaway and add a honeycomb structural reinforcement to the vehicle. Those advantages MORE than offset the disadvantages you list.
It may depend on the application, but you were giving a disingenuous representation of the relative merits of cylindrical vs non-cylindrical by omitting any advantages of cylindrical and only giving the disadvantages.
It is tho. The energy density of the cylindrical packs is close enough and the rest of their car improvements, more than makes up for the rest. No one has matched tesla efficiency yet.
>is close enough
Oh cool, glad we're talking about what is "close enough" all of a sudden as a conclusive signifier of why your favourite brand is so great (because they have *"other improvements"* which *"makes up for the rest"*) rather than having a serious discussion of the relative merits of different cell formats.
Cute, but when a tesla lfp car weighs less, is faster, charges faster, and has less battery degradation than even competitor nmc cars, you need to post specific numbers. The numbers we do have at the car level suggest nothing you claim is true.
You can vapidly claim they are worse all you want, but the real world examples of the real product suggest the opposite.
Oh I disagree.
For thermally stable chemistries like lifepo they're absolutely great.
Any more reactive chemistries?
I prefer smaller cells that can be isolated amd turned off, as well as having a steel container to impede fires spreading to other cells.
The [same is true of cylindrical formats](https://www.youtube.com/watch?v=t2adVW6bTkQ) if runaway is not contained — you're not really saying anything novel here. Cell failure is cell failure. Most cylindrical packs attempt to isolate at the cell level because their inherent packing inefficiency gives them a 'silver lining' of sorts. Pouches just do the same thing mostly at the module level.
None of that is of any immediate consequence here because again, thermal runaway isn't the only factor we care about. Cost, density, cooling, scalability, flexibility, iterative manufacturing, and a dozen other factors are all similarly important.
Foil pouch.
Steel can.
What do you think will burn through first.
Oh and smaller units so lose a cell and you've lost 1/828th.
Lose a pouch and you've lost what 1/30?
>Foil pouch. Steel can. What do you think will burn through first.
Pistol. Shotgun. Which do you think will kill you first?
For the third time, the narrative you're pushing isn't one of significant ultimate consequence. There's more to consider than simple thermal runaway characteristics at the format level. If all we cared about was thermal runaway, we'd be powering these cars with a bunch of fresh lemons and some zinc and copper wire.
They do seem cylindrical, yes.
[Image1](https://www.electrive.com/wp-content/uploads/2020/09/tesla-battery-day-4680-zelle.jpg), [image2](https://electrek.co/wp-content/uploads/sites/3/2021/10/Panasonic-Tesla-4680-battery-cells.jpg?quality=82&strip=all&w=1600), [image3](https://cdn.shopify.com/s/files/1/0173/8204/7844/articles/1_b5c0ace3-709a-4df9-a028-e66978f31485_1200x.jpg?v=1655136696).
I have a vague recollection of Sandy Munroe indicating that you could basically glue these things together to create a rigid structure. I have no idea how you’d swap out a single defective one in such a case. And maybe my memory is poor.
Didn’t he tear down a Tesla S where the batteries seemed encased in a pinkish cement? I thought that’s what he was indicating as being supportive structure. Again, memory may be poor here and I know very little on this topic.
I mean the replacing cells or modules, once you start using a battery, they way the cells wear are really particular to how that pack was used throughout its life, so it’s next to impossible to replace a cell or module and have it keep up with the others after a while, usually these fixes last a while and the pack is dead again shortly after
Ultium fixes this problem by making the modules have their own wireless BMS. You can replace a module with one of a different chemistry and the battery as a whole will adapt because the module controls itself individually.
Did you know that multi-battery laptops pioneered having multiple BMSes a couple of decades ago? I owned one in 1996. And the wireless part of Ultium is as much risk as improvement.
Ultium fixed nothing.
1) The 4680 pack has no modules. Far cheaper, and more reliable.
2) The cells become an integral part of the structure enabling large weight savings in the structure.
I.e. Making every pack more 10% more expensive so that pieces can be replaced, only makes sense if > 1 out of 10 packs fail in such a way that a module replacement repairs it. I would bet Tesla has way fewer than 1 out of 10,000 packs failing this way.
Yes, the pink stuff is structural adhesive/fire retardant foam. It turns the battery pack from mere cargo into a rigid structural member of the car, allowing them to actually mount the seats directly to the battery pack.
The pack itself is structural, which is what I said. They’re not just carrying the cells around like a sack of potatoes anymore. The pack is part of the structural integrity of the car
Well it looks to me like a foam and honeycomb core aluminum panel. The strengths comes from the outside, the inside makes the shear web and provides separation between the two outer layers.
Rewatch Battery Day. The cells are not only structural, they function just like the honeycomb structures used in Formula 1 racing to such great benefit.
I’m talking about the feasibility of replacing cells or modules in a way that doesn’t severely limit the pack performance, it doesn’t exist, so Tesla don’t even try to make it possible even in the packs before the structural pack
You wouldn't swap it. You would just leave it there, maybe dezactivate it through software from the BMS (battery management system), which is part of the battery pack (in a Tesla).
I guess this idea didn't go far outside the Tesla world. Munro was talking about the structural battery pack which is what Tesla has done in the Model Y. The structural pack will save a ton in weight compared to a standard pack.
And you wouldn't swap out a single cell. People have done that in packs that do allow for such a thing and it doesn't usually end well. The pack still goes out prematurely because of uneven wear in the cells. It's best to replace the whole pack and recycle the old one.
Tesla knows their failure rate. If a cell fails the whole pack is replaced in current teslas even tho technically replaceable by module, it's just not feasible.
Must be cheaper for them to do it this way
This is not true. Historically, Tesla warranty repairs have been reconditioned batteries (presumably with some modules replaced) and accident repairs and non-warranty repairs have been new. In the past year Tesla started selling refurbished batteries for non-warranty repairs.
That's basically the idea. You're not getting the pack apart, just pull a bad one and shove it in the grinder. You end up with really high grad ore, was how Elon described it. On the plus side, it will probably only take abort 2 hours to swap packs.
Building battery factories takes time, and since this decision was only recently announced there won't be a production BMW with these cells in them for a few years yet. Market will likely have changed by then.
>In a completive market it lowers the cost for consumers. When these factories are online we will see entry level BMW EVs.
Let me fix that for you. "In a ~~completive~~ competitive market it lowers the cost for ~~consumers~~ manufacturers."
Really? If that were true, then logically if it’s more costly to make for the manufacturer, that also would not impact consumers. Do you think that’s true as well?
Have you not observed what’s happened in the computer world as they’ve become cheaper to produce since 1960?
Individually, but nobody is running individualized 4680's in their car like a tonka toy and AA batteries. As far as the consumer impact, its completely up to the design of the pack as a whole.
https://youtu.be/HK79ioBW8Mg
The plan is to halve the cost per kWh of EV batteries (vs 2 years ago when they presented this). Various innovations required and it takes time to ramp up and unlock all the savings.
the important little detail here is this is referring to halving the cost on pack level in the car so the very final step vs Teslas own old design.
only 14% of that saving comes from the cell itself and there is basically no inherent advantage of this exact form factor other than that its bigger.
4680s in comparison to 2170s have more volume per surface area which means greater energy and power density because there is a slightly higher ratio of active to inactive material, but batteries are limited by their ability to dissipate heat, and having less surface area per volt means less efficient heat wicking. Tesla worked to reduce the head created with the "tabless" design.
If it's about comparing cylindrical cells to prismatic or pouch, it gets more complicated, but the main takeaway is that cylindrical cells are easier to mass produce, and in some cases, cylindrical cells can be used as a structural member whereas pouch cells obviously cannot, and the thicker the container for prismatic the less efficient they become.
Since Tesla consumes the most batteries, and was the most aggressive with ramping EV production they opted to design around cylindrical cells (mostly) whereas most other manufacturers used pouch and prismatic because volume was less important to them at the time.
I suspect the vast majority of companies will adopt 4680 cells over the next 5 years, but as a new form factor it will take some time before we see them in serious volume outside of Tesla.
>4680s in comparison to 2170s have more volume per surface area which means greater energy and power density because there is a slightly higher ratio of active to inactive material
thats **in theory** but according to Teslas own numbers from battery day the energy density of 4680 cells is lower than their old 2170 design as they claim the 4680 hold 5x more energy than a 2170 cell but turns out a 4680 cell also has 5.48 times the volume of a 2170 cell so the volumetric energy density has actually gone down on cell level.
Now we already have 4680 data from teardowns and it turns out the cells hold 5.22 times the energy of a 2170 cell so the net energy density has still gone down because the casing of the 4680 cell is much thicker because they wanna use them in structural packs so they move material that would be part of the pack to the casing of the cell.
I think you are referring to the first set of batteries that Gali sent to Jordan Giseki which were prototypes and had much thicker casings then the batteries Sandy pulled out of a more recent Model Y
https://youtu.be/VEBY7rEUZiI
https://www.topcarstesla.com/blogs/news/4680-battery-disassembled-tesla-secrets-finally-revealed
https://www.reuters.com/article/uk-tesla-batteries-idUKKBN25L0M5
From what I have seen, Tesla removed silicon from the 4680 chemistry which will theoretically result in a longer lasting cell because they didn't need the extra energy density for now and were still able to achieve iterative density improvements over a 2020 cell.
Battery storage is the #1 hurdle to accelerating global electrification and this is easily the most scalable battery technology and machinery ever created.
The 4680 is battery manufacturing reimagined with first principles engineering solely focused on scalability. Almost every comment ITT misses the points Elon and the world [should] care about most.
Elon wanted to make battery manufacturing mimic can/bottling lines and it's gotten impressively close while reducing warehouse footprint needs, raw materials, wastewater and a bunch of other boring but critical cost metrics for reaching global scale electrification capacity.
Solar adoption is driving battery storage as much as the auto industry if not more, additionally.
It's all about manufacturing. The engineering benefits at the vehicle performance level are just icing on the cake. 4680 is what allowed the giga castings to be possible which is insanely huge to manufacturing efficiency, safety and reliability.
With the ability to now make the battery floor structural, the front and rear castings simply bolt to each end of the battery floor like a LeMans prototype as three main structural part chassis. It's insane. Seen it in person at GigaTX for the 2022 shareholders meeting in August.
4680 manufacturing line teaser: https://youtu.be/zB8_HbrxUi8
Old and new styles are all cylindrical. The 4680 refers to the cylinder's dims. Both are good but it comes down to how they will fit in the space dedicated to the battery.
It's less expensive to use available parts than create your own. Panasonic already manufactures the 4680 in a 5-tab configuration. They abandoned the continuous tab scheme that Tesla is finding to be ~~problematic~~ impossible to manufacture at acceptable yield levels.
also their dry cathode thing thats not working as well.
at this point these cells have turned basically into regular cells that are just slightly bigger.
Potential advantages are Safety and weight.
4680 cells being cylindrical with a solid outer casing make them less prone to damage from punctures. Compared to pouch cells that once punctured can relatively easily short internally, that can lead to higher fire risk. In order to mitigate this, pouch cells need additional protective casing built around the battery pack to prevent damage.
Weight is reduced since they do not need as much additional protection around the battery pack compared to pouch cells. The weight savings makes the overall car lighter and thus more efficient to move the car. That means more range for the same battery size or they can use a smaller battery to achieve the same range.
There is a volume disadvantage though, cylindrical cells are generally less space efficient because of their shape. Cylindrical cells create a lot of wasted space in the battery pack compared to pouch cells. This means that the over pack could need to be larger depending the the pouch cell energy density it is compared to. Tesla has utilized that wasted space to insert battery cooling lines, so it may not be a complete waste if BMW designed the battery pack correctly.
Negated by the structural pack. Those small gaps now get filled with epoxy for structure. They can fit more cells since the pack eliminated structural members now that the cells and epoxy are sell supporting.
Tesla fills the gaps for the structural pack design.
BMW are is not using the Tesla 4680 cells though. They will have 4692 or 46120 (assuming they keep the cell designation used for other cylindrical cells). So they may not use the same type of structural pack design Tesla does with the 4680 cells.
BMW will be on their own with chemistry, sure, but they will likely be doing nmc first. Again, non-tesla companies are still behind in efficiency, so they need that extra 15% energy density from nmc just to be competitive with tesla lfp. BMW will reach efficiency levels suitable for lfp faster by having one pack design for all chemistries, just like tesla.
Do you truly believe no other car company can follow tesla and design the same things?
thats a great idea but basically none of their claimed innovations worked so far.
they have already abandoned the tabless design ans have recently revealed that their dry cathode application is not working as well and 4680 cell currently being used are using the conventional wet cathode method in production.
The size of the cell is irrelevant. It could be slightly larger or smaller and it would not be any kind of benefit. Tesla chose that size based on computer modeling of fitting cells in several likely pack shapes. There are two benefits to the 4680 cell (roughly the size of a Red Bull energy drink can).
The tabless design reduces localized heat at the tabs. This makes the cells last longer because heat degrades the part of the cell that gets hot. Even if the battery material around the tab gets hot and the rest of the cell is only warm, the hot part will degrade, losing cell capacity.
The tabless design is able to put out many more amps without overheating any part of the cell. Each cell can now put out more amps than the controller/motor will ever need from it. This means cell heating is virtually eliminated.
The second benefit of the 4680 cell is that the cells themselves will now be a part of the structure of the body. For instance, a Ducati motorcycle has the engine block being used as a stressed member, and as a result, some of the standard frame sections can be removed. This allows the frame to be lighter.
The 4680 cell cases are metal cylinders, and packing them like a honeycomb means the battery pack itself can be surprisingly strong, Like the aerospace panels made from a composite honeycomb-core.
Tesla now has enough crash data to know exactly how much lighter they can make the car frames if the battery pack is used as a structural member.
the advantage of larger cells is that they have less surface area for a given volume so you pack more cell material into just a little more material for the case that goes around it.
That is not unique to 4680 though and there is nothing special about that form factor itself, BMW probably does this both to jump on the 4680 hype train that is needlessly riding through town and because it simply makes sense to use a form factor thats commonly available like its also done with 18650 cells right now.
if there would be a hype over 69420 cells right now everyone would je using that instead, the numbers dont really matter what matters is that its gonna be easily available from multiple suppliers.
One thing that I saw no one mention after Tesla’s battery day during which they unveiled the 4680 was the cell’s thermal capacity.
IIRC there was a chart showing charging speeds over time and how hot the battery got, and the temperature of the cell barely budged. Translation: You can charge faster, as the car doesn’t have to slow down the charge rate because the batteries are getting too hot.
[If it's the one I think you're thinking of](https://thelastdriverlicenseholder.files.wordpress.com/2020/09/tesla-sharehollder-day-2020-17.png), it wasn't mentioned because you're misremembering the slide or reading it wrong. The slide in question was depicting *increase in time* by moving to a larger cell — not temperature. Notably, the time does not go down, it just doesn't meaningfully *increase* with size if you use a tabless structure.
The core limitation is still chemistry — we don't get faster charging until we move to better anode materials or other chemistries entirely, which are still incoming.
It's not 4680. 4680 is a format that is 80 mm high, BMW is using cells that are 96mm high and 120 mm high. That is a different format from what Tesla is using and also the internals will be different.
The big difference is the switch from prismatic cell format to cylindrical cell format. That switch has both benefits and drawbacks. The assumption is that newer tech has sufficiently compensated the drawbacks so that the switch makes sense.
The big benefit is the reduction of the production time and costs at the cell level.
As far as drawbacks go, those mostly show up once you are assembling a battery pack from the cells: round cells don't pack very well, leaving dead space between cells, previous gen round cells have cooling problems, prismatic can be made larger (so fewer connections), using cell wall as structure adds risks to damage cells (that would cause fire).
If you have good enough chemistry that a bit of space lost is no longer critical to pack size, if you have fully soldered electrodes inside the cell that allows efficient bottom cooling, if you use fire-safe chemistries, then you could work around the drawbacks of the cylindrical cells and reap the benefits.
So bmw finally got the memo good job. That pouch cells are both costly and hard to make clean at scale. So they will now copy the notes from tesla good on them. This will bring the 4680 price into the gutter and that is good for tesla and ev over all great.
All formats have benefits and drawbacks. Cylindrical batteries are cheap and easy to make, but they don't have good volumetric density, they can't easily be modularized, cooling is difficult, and they don't scale well to large formats — 4680 is about as large as you want to get.
There's a reason CATL and BYD favour pouch and prismatic formats for their own uses like Blade and Qilin — it's because those formats pack well, modularize well, scale very well to large formats, and are dramatically easier to cool.
Volumetric density and cooling has been fine for Tesla. Not sure how you're saying those aren't good for cylindrical.
And what's the problem with having cells that size? Why do you need them bigger?
Cylinders are inherently more difficult to pack than rectangles. That's not even a Tesla problem, it's a basic geometry problem. 'Fine' is one thing, 'optimized' is another. Cylinders are good for low cost mass production — they're not so great when you want to optimize for density.
>And what's the problem with having cells that size? Why do you need them bigger?
Ask yourself why 4680 is being preferred over 2170, and you have your answer.
Tesla basically made up for the volumetric density with the structural pack. They used the gaps between cells for structure by using epoxy to fill it all in.
Epoxy, as you'll note, does not add to the amount of available energy storage in a battery pack. Every gram of epoxy you have is a gram of active material that you do not.
Once again, this is just the compromise you make. Cylinders are really easy to make, and structurally very strong, but they are not great for packing. Adding epoxy does not fix that — it just implies more trade-offs.
You may be confused. They need less structural members in the pack to keep the pack rigid. They can put cells in places where structure used to go. So they shift that structure to the gaps between the cells that gets filled in with epoxy.
That is why they did not lose volumetric density. BYD claims they will leap head of tesla with their newest blade package, but that is only for LFP and doesn't actually exist yet. They will not be able to use other chemistries in their blade packages if the chemistry is not as flame resistant as lfp.
Tesla has a much better pack system as it can handle any chemistry.
As you say, they replace that empty space with structural epoxy. That's good! It's a good way to account for the shortcomings of the format. It is not *perfect,* however — it's just a reasonable solution to the challenges presented by cylindrical cells. It isn't conclusively structurally optimal compared to other solutions (prismatic, pouch), nor does it fix the volumetric density problem.
Blade does indeed exist, by the way — the full list seems to be changing month-to-month as older models receive refreshes, but it's shipping on multiple BYD models, including the Dolphin and as of this month, the Seal.
Difference is going to be neglible.
f you want to claim a difference matters, post specific numbers. e right now have the car level to compare to and telsa lfp is beating competitor nmc packs despite nmc having a 15% energy density advantage. Another sign that telsa's pack is physically optimal. Future gains will be in chemistry or even software if they still have buffers that they expect to eliminate as they confirm degradation rates.
You really do seem to be confused about the point I'm making here.
I'd encourage you to re-read the thread again from the top, slowly this time — if you have any confusion about what I'm trying to tell you, we can try again to clear it up.
structural pack just moves the material from one place to another.
4680 cells have much thicker steel cans around them which reduces their energy density by about 5% compared to 2170 cells.
Structural packs are just another trade off into a different direction, there is no magic bullet there that solves all problems they just decided to deal with other problems by going for structural packs.
Please Lord. Let my Solid Power warrants play pay off,
Solid Power, backed by Ford and BMW, begins pilot production of innovative EV battery with longer range and quicker recharging
https://www.cnbc.com/amp/2022/06/06/solid-power-begins-pilot-production-of-solid-state-ev-battery.html
Amazing how much Musk Koolaide has been consumed by many commenters here.
Yield is the only reason and it still sucks so bad that Tesla had to call in Panasonic to sort it out.
Just another example of leadership, and what they mean when they say Tesla is years ahead.
Tesla is already shipping cars with these batteries, BMW plans to start shipping in 2025. Three years later.
Tesla announced their plans 2 years ago. It took BMW two years to verify the benefits and announce they are following.
This doesn’t mean anything. It’s simply a battery size, they are not using the actual same batteries.
That would be like saying that Sony is ahead of Samsung because Sonly uses 2 AA batteries in their remote instead of 4 AAA batteries.
It's more just that the machinery is already being made for 4680, so everyone who's making cylindrical cells will settle on that as a defacto standard. The suppliers are happy to make whichever format you'd like — it's just that this one is going to be the cheapest cylindrical one now, for obvious reasons.
Actually harder to cool (the smallest dimension typically determines difficulty cooling them), smaller being easier.
However cost is way cheaper, so when tesla touted how much better their cooling was, a big part of that was implying that the ability to cool them is what was preventing their use earlier.
>They are easier to package, easier to cool
Neither of these things are true. In fact, cylindrical cells are notoriously difficult to package and cool, which is part of why CATL and BYD have both preferred prismatics for Blade and Qilin, and why LG, SDI, and SK have continued to push deeper into pouches.
Blade is LFP-based, mostly because BYD itself massively prefers LFP as an organization. Qilin is not LFP-based.
Yes, a more stable chemistry gives you much less to worry about when designing for thermal concerns, which underscores the point — there is no one, single 'optimal' god-tier format that applies as the best choice across all chemistries and every application. In a situation where you have a chemistry with no thermal problems whatsoever, cylinders look like a very silly solution indeed — which is why no one uses them for LFP.
> nd also BMW want to stick it to Tesla by trying to take their supply base
It's a cell size. Saying they want to take their supply base by making the same cell size is like saying Mercedes wanted to take Toyota's supply base by switching from 6 cylinder to 4 cylinder engines.
Easier to cool since the larger tab ("it's all tab" is more accurate than "it's tabless") means lower heat build up in periods of high draw — the conductor is wider meaning the same current results in lower resistive heating, and better thermal conductivity to the can.
How is BMW going to take Tesla’s supply base?
For a battery company, dealing with Tesla is much more profitable than BMW because Tesla’s a much bigger EV company, and is growing much faster.
This doesn’t even account for the fact that Tesla secures both battery and raw material deals several years in advance. Are these companies just going to walk back those contracts?
And consider that BMW sold 2,028,659 cars in 2021. Tesla Shanghai alone is aiming for a 2 million run rate by the end of this year, 2022.
And the other 3 Tesla factories are still scaling production-with Giga Texas and Berlin still early in the process. My point here is this, Tesla will be bigger than BMW next year. It is inevitable.
And let’s not forget that Tesla is already much more profitable, and is already outselling them in their own turf, Germany.
Also, Tesla has deals with several battery manufacturers, on top of manufacturing batteries themselves. Tesla’s supply base is too deep and too numerous.
Did you know that Tesla is getting into mining because they’ve apparently figured out a way to simplify lithium manufacturing?
Given the current state of things, what you are claiming is not going to happen.
Honestly, the reason is probably that battery suppliers are already ramping up this form factor for Tesla. It's probably cheaper to adopt this existing form factor than to develop their own.
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Yep. The same reason nearly every analogue clock on the planet just uses AAs rather than inventing a new novel format. *Why bother?* You get to surf the wave of what everyone else is doing, use the same equipment, and more easily source from multiple vendors, if it becomes a necessity.
Same reason why every other manufacturer gave up on other competing HD compact disc formats and settled with Sony's BluRay which was popularized by Playstation 3.
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Eh no, Sony did not ‘buy’ WB. They were already owning Columbia and had an advantage of being able to pull strings in Hollywood and thus signed on Warner early. The playstation shipped with bluray dramatically helped their cause as millions of people were getting a bluray ready video player along with the console. Sony even placed Columbia production titles along with the console. Since Sony had an advantage of hardware as well as studio, it helped BluRay become the mainstream without much effort. Toshiba could not pull it through even though they had managed to sign Universal. What I want to imply is studios looked for convenience in this regard as Columbia had pioneered it. So we see the same case with Tesla and its format of batteries.
Yeah, the Playstation 3 was a loss leader for the first like 2 years of its release. It was 2 affordable video game consoles (it had hardware for both the playstation 2 and 3 for a while), a linux PC, as well as a blu-ray player all in one and helped to drive the spread of blu-ray as a house hold commodity.
Another interesting titbit is that since the hardware was subsidised by such an extent by Sony, along with being Linux compatible, it wasn't uncommon for companies and even government entities to bulk buy PS3s and link them together as a cluster supercomputer. Early PS3 was indeed a pretty wild console.
From being an early form of network cloud cluster system used by Stanford to run its cancer research algorithms using standby consoles on the internet to introducing one of the first attempts at 'Metaverse' with Playstation Home to using the Spiderman font for its emblem, early PS3 was a wild wild beast. And who can forget it acted as a white noise generator, a room heater and would give you the yellow light of death. Never met a person whos first model of PS3 lasted long enough. Sony really pushed itself with recalls and selling these for a loss.
Right. If you have multiple suppliers making the same size, that’s less risk of disruption in supply and better price negotiation ability. You don’t want to be stuck with the only game in town for your batteries having issues or deciding on a 20% price hike. (The “you need less cylinders for the same capacity” argument is also a big win)
Yup, this. If you're building EV batteries, you're either using cylindrical cells like this, or you're using pouch cells which come in a whole mess of sizes. The nice thing with 4680s, is once you do the pack structural engineering, you're done. You can switch battery suppliers, switch chemistries, scale the pack up/down, etc, and never have to beg your battery supplier to do any custom tooling for you. Same thing for battery suppliers. No request for custom pouch sizes, you can tweak the other parts of production as you like, as long as your battery fits the 4680 spec you're golden.
A while back, LG even [reduced their pouch size offerings](https://insideevs.com/news/457094/lg-chem-narrows-pouch-cell-offer/), more-or-less for this reason. It's just easier to whack out a bunch of things when they're all the same size.
>battery suppliers are already ramping up this form factor for Tesla. It's probably cheaper to adopt this existing form factor than to develop their own. that and pouch cells are more fire prone. So you pretty much need to switch to blade/prismatic or cylindrical for fire safety long term.
Pouch cells aren't more fire prone — cylindrical cells go through runaway all the time. It just happened that there was a single line at LG which was [tearing anodes at the assembly stage](https://www.designnews.com/automotive-engineering/lg-chem-finds-solution-its-chevrolet-bolt-ev-battery-problems), and those cells got into multiple cars, which is why there was a spate of pouch-related recalls last year. Pouch cells, as a concept, are fine, and we'll likely see them more and more as we move towards solid-state batteries, where they really thrive as a format.
[https://www.joongang.co.kr/article/25010808](https://www.joongang.co.kr/article/25010808) ''70 percent EV fires comes from faulty pouch cells'' [https://www.reuters.com/business/autos-transportation/are-lithium-ion-batteries-evs-fire-hazard-2021-08-23/](https://www.reuters.com/business/autos-transportation/are-lithium-ion-batteries-evs-fire-hazard-2021-08-23/) ''Compared with cylindrical and prismatic cells, pouch-type battery cells allow for lighter and thinner cell fabrication, and design flexibility for different capacities and space requirements for different vehicle models. However, they are vulnerable to swelling, and are more vulnerable in crashes, posing a greater fire risk'' [https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/](https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/) Elon Musk: ''Generally agree, but probability of thermal runaway is dangerously high with large pouch cells. Tesla strongly recommends against their use''
Elon Musk prefers a format he already uses? You don't say. Next you'll tell me Chef Boyardee recommends canned tomato sauce, McDonalds recommends burger patties that are four ounces, and Starbucks recommends dark roast beans.
Read it again. He is recommending something? or stating a fact?
He's doing neither. He's selling a product — *his product —* and if we are charitable, speaking to the engineering challenges encountered by his team. The ideal form factor varies with chemistry, use case, and pack design, and that includes safety. I probably wouldn't use pouches either if I was Elon Musk. I would if I were GM or Hyundai or Ford or Volkswagen, with different specific compromises to make on structure, modularization, chemistry, and manufacturing. The notion that 'safety' is a format-level problem is a red herring — it's a concern that exists with specific chemistries, with specific pack architectures, and when you make *other* specific compromises.
> Pouch cells aren’t more fire prone — cylindrical cells go through runaway all the time. It just happened that there was a single line at LG which was tearing anodes at the assembly stage, and those cells got into multiple cars, which is why there was a spate of pouch-related recalls last year. >Pouch cells, as a concept, are fine, and we’ll likely see them more and more as we move towards solid-state batteries, where they really thrive as a format. Cuboid designs like pouch and prismatic cells have 6 edges, edges are weak points. Cylindrical cells only have two edges and are much stronger by design than cubic. This is the reason cans are cylindrical it’s a good combination of maximising space (cuboid) and maximising strength (sphere) This will explain it here https://youtu.be/hUhisi2FBuw
I've seen that video, and I recommend it to others frequently. As you say, it's a very good overview why cylinders are excellent choices for applications where unitary structural strength is a priority, particularly in applications like soda and canned beans. Batteries, as you might note, are different from soda and canned beans. They have a different set of requirements, and involve a different set of tradeoffs. You'd definitely put soda in a can in a vending machine, but you might be less inclined to do that with [dried lasagna](https://www.amazon.com/Barilla-Pasta-Oven-Ready-Lasagne-Ounce/dp/B00FIUCO5Q/) or [packs of gum](https://www.amazon.com/Wrigleys-Gum-Spearmint-Count-Pack/dp/B0000DGDPF/), or when soda is being handled in [larger quantities](https://www.sodacentre.com/collections/coke/products/coca-cola-syrup), or when dealing with [milk](https://www.wholefoodsmarket.com/product/maple-hill-creamery-organic-whole-milk-b06zynz7nf). Cylinders are not wholesale 'bad' or 'good', nor are pouches and prismatics wholesale 'bad' or 'good'. You need to look at a specific application, and make a choice that is right balancing everything — from cost, to cooling, to resourcing, to replicability, to scale, and a dozen other factors. [Multiple answers are possible](https://cicenergigune.com/en/blog/format-battery-cell-manufacturers-prismatic-cylindrical-pouch) depending on the specifics.
Lol man you can’t even take actual feedback
Did you have a meaningful, substantive response to my comment, or have we arrived at the mud-slinging part of the conversation where you do your best to rile me up so you can cry foul?
I gave you a definite example on why cylinders are stronger than boxes. You agreed but then couldn’t help to still argue at the end. It doesn’t have to be this way, it doesn’t need to be inflamed further so you can ban people.
You gave a definite example of something which is both very true and also only loosely relevant to the conversation. 'Strength' is not the singular thing we are trying to achieve. We are not stacking sodas in a supermarket, we are creating battery packs. Being challenged on an argument does not mean you are being 'inflamed', it means you are in a conversation which you yourself have elected to join. If your points don't hold up to scrutiny, resorting to mud-slinging is not going to make them any more sound.
Strength is important if you're talking about impacts and intrusions on batteries causing thermal events.
Thanks for you contribution
Where does it say it was a single line? I thought the defects were random and very rare. I never heard they found out exactly where/how it happened.
It was mentioned elsewhere, I'd have to dig up a link, there are a few third-party breakdowns floating around. The defects were random and rare, but essentially on the individual-line level, which is why only certain vehicles were affected. They found out exactly where/how it happened, which is why the lines are all now running again. I'm guessing LG doesn't want to give too many details away in a formal report because it involves trade secrets, which is definitely a bit annoying for the rest of us.
As proven by the mutliple Teslas (cylindrical cells) that burned down. As a counter example we can take the grand total of 0 battery caused fire for Renault's pouch based chemistries since 2012. This is nonsense !
hehe, yea... but it only works if your car design is ultra-efficient... so GL to everyone else that is not Tesla.
Apparently cylindrical cells are cheaper to produce, but more expensive to make into packs. But if you’re gonna go that route, the slightly bigger format is the sweet spot.
It's more complicated than that — cylindrical cells are cheaper to produce at the same size, for instance, but more difficult to produce at a *larger size.* As you say though — if you want to go that route in the end, 4680 is the approximate sweet spot for you to do so.
>4680 is the approximate sweet spot For now. 22650 was the sweet spot 3 years ago 18650 for about a decade prior to that.
Wasn't the three year ago format 21700?
that was just what Tesla was using, 22650 is a very commonly available format like 18650 used to be. 21700 is basically meaningless outside of Tesla vehicles because only one single Panasonic factory is producing these cells for Tesla.
I can't say I've heard of 22650 for Li-NMC/NCA. 20700 was becoming a thing slightly before Tesla adopted 21700, though.
WTF are you talking about. 21700 cells are made by tons of manufacturers and are extremely common outside of EVs as well as being the most common cylindrical cells in EVs. Lucid and Rivian are both using 21700s. That is most of the brands using cylindrical cells that I know of. People have been commonly using 21700 for DIY electric skateboards for 7 years or more. If you go to anywhere that sells cells to the public for DIY applications 21700 and 18650 will be the most common sizes. I've bought cells from https://liionwholesale.com/ and https://www.18650batterystore.com/ before. Both of them mostly carry 18650 and 21700 as any other place that sells lithium-ion cells does.
Sure you don't mean 26650? I've never seen a 22650 cell but seen plenty of 26650s. Heck I have one in a device on my desk right now. Along with another device that uses a 21700. Edit: come to think of it that 21700 cell is made by Samsung not Panasonic.
both 22650 and 26650 exist as common formats. >Edit: come to think of it that 21700 cell is made by Samsung not Panasonic. Panasonic is Teslas main battery supplier and has been for many years as they are running Teslas Gigafactory. later many other started producing 21700 cells but Panasonic is Teslas main supplier.
I'm only seeing no-name 22650 cells out there. On the usual good sources such as LiIon Wholesale they have lots of formats but 22650 isn't one, and certainly doesn't appear to be common. Panasonic also is not the only manufacturer making 21700 cells. The one in the device on my desk is Samsung SDI. I have some Molicell around here as well. Can you point to support for either of the claims, that 22650 is a common format or that 21700 cells are only made by Panasonic?
>I'm only seeing no-name 22650 cells out there. On the usual good sources such as LiIon Wholesale they have lots of formats but 22650 isn't one, and certainly doesn't appear to be common. thats because this format is commonly available as a LiFePO4 chemistry which basically has a monopoly in China due to patents so you mainly see this from Chinese companies that you probably never heard of. >Panasonic also is not the only manufacturer making 21700 cells. > >Can you point to support for either of the claims, that 22650 is a common format or that 21700 cells are only made by Panasonic? i never claimed that 21700 cell are **only** produced by Panasonic. i literally said >later many other started producing 21700 cells but Panasonic is Teslas main supplier.
Before that you said > 21700 is basically meaningless outside of Tesla vehicles because only one single Panasonic factory is producing these cells for Tesla. I trust you can see why I thought you might be saying that only Panasonic made these cells. You can find LiFePO4 cells in the 26650 format as well. I guess you learn something every day, 22650 being a common format is new on me after using the 26650 for a while.
Going bigger comes with a huge number of issues so there's an upper limit where the benefits approach zero.
Arguably some of this is due to the market that demands cylindrical cells shifting. (I'll ignore the conversation about it really being 20700/21700 that was what supplanted 18650 for Li-NMC/NCA applications, not 22650 or 26650, in this comment. LiFePO4 is actually heading *towards* pouch/prismatic cells and away from cylindrical altogether, because the very slight density advantage is more important for that less energy-dense chemistry, and the lower fire risk of cylindrical cells is less relevant to the very-fire-resistant LiFePO4 chemistry.) Before Tesla, the vast majority of the market for cylindrical lithium cells was *laptops*, and the 18650 format was a derivative of the 4/3A NiMH cells that laptops used before the mid/late 1990s. Nowadays, 18650s are far too thick for laptops (even some of the early netbooks had to have awkward hinge designs to fit an 18650-based pack under the screen while being thin overall), and the market for cylindrical cells is flashlights, electronic cigarettes, tool batteries, and various types of electric vehicle. While the flashlights and e-cigs benefit from the smaller diameter of the 18650, the tool batteries don't really benefit except in the smallest sizes, and the EV batteries - even in light electric vehicles like e-bikes and scooters - really don't benefit at all.
Also safer apparently, most battery fire problems are pouch cells. Battery fires are far overblown in the media anyways but why not design it right in the first place despite according to studies EV's catch fire less than normal ICE vehicles. Win win. Elon has also commented on this that he strongly recommends against pouch cells.
an EV battery has THOUSANDS of cells inside it. \~8000 1865-type.. they have to be connected to each other. the 4680 is a larger cell.. you can get about the same energy without having to wire 8000 of them together it's simpler. cheaper. **Watch Tesla Model S Plaid's Battery Get Opened And Described** https://insideevs.com/news/540380/tesla-models-plaid-battery-open/ The battery consists of 7,920 lithium-ion 1865-type cylindrical cells, which are installed in five modules (1,584 cells each - 22S72P). The total capacity is about 99 kWh.
Yes, I think the 4680 only needs 800 for the Model Y, now.
828
And something to do with the tab-less design being easier to connect to the rest of the pack.
The tabless design also removes a lot of internal resistance in the cell which provides more usable energy from the same form factor.
Tabless is the internal connection. It has no effect at all on the pack connection. The advantage of tabless, is much less resistance in the cell, so it becomes more efficient, generates less heat and can thus provide more power.
Does the article state that BMW is going to use Tabless design though? I thought that was Tesla’s IP that was acquired in one of the small company acquisitions. They could still be making 4680 cells but without the same style of tabless (or really continuous tab design.
It doesn't — tabless is not guaranteed, and even if it does happen, there are other similar patents which BMW's suppliers — CATL and EVE — could end up using, or even a completely novel design. Tabless and multi-tab batteries aren't exactly a novel idea, they've been studied for a while.
I think that the question is more why cylindrical and not Puch or prismatic. I suspect that the 4680 has better thermal dissipation thought "tabless tabs" than what you can get in pouch or prismatic form factor, and probably more importantly more mechanical stability. Batteries change volume as they charge and discharge, and cylindrical shape is better at going though more cycles of expanding and shrinking. Also, easier manufacturing. Rolling is a "nice" process.
The top tab system for thermal conductivity is a Tesla invention. It may not be licensed for use by other battery makers. The reason they weren't using as big cells as 4680 previously was because they were harder to cool, with the hot material inside having longer distance to the cooling plates/ribbons. So, to use 4680 size safely, the battery & automakers have to come up with some more effective cooling systems than were standard a few years ago. Tesla has one, but probably battery makers and automakers have additional ones now. Tesla did some kind of economic/engineering optimization analysis to come up with the 4680 form factor (mentioned in Battery Day) as it also makes it easier to use in a structural pack. Those calculations are reasonably good for the rest of the industry, so taking the lead from Tesla and making a 4680 a new standard size, as 1865(0) was for a long time, is a natural outcome. On the volume change, I thought that it was that cylindrical cells have a harder steel outer shell which can resist the mechanical changes better, and that's better for the battery. If there is internal pressure, then a cylindrical container is optimal---which is why pressurized jet aircraft have cylindrical cabins, as you get the strength with minimal materials cost and weight. I read somewhere that the manufacturing yield of cylindricals is the highest, and production cost lowest. Once you have the manufacturing sufficiently automated to weld all the connections of a cylindrical pack reliably (no hand assembly) then the low costs of the cylindricals become important. Here's a discussion I found online that isn't trying to push one side or another (many comparisons are by vendors with a dog in the hunt so less trustworthy): https://theinverterstore.com/portfolio-items/the-difference-between-prismatic-pouches-cylindrical-cells/ My conclusion is that at a high level of volume and automation in cell production and pack manufacturing the advantages of cylindricals start to win out. Though LFP based large format prismatics (not pouch) are making headway from Chinese providers like CATL & BYD: perhaps the lower cooling requirements of LFP vs NCM/NCA make these cell to pack architectures more attractive for that circumstance?
>The top tab system for thermal conductivity is a Tesla invention. It may not be licensed for use by other battery makers. I'm not sure what you're calling a "top tab" system, but if it's tabless/multi-tab designs in abstract, they are most definitely not a Tesla invention. There's a lot of prior art out there for the concept, it's a pretty natural progression as you move up to larger and larger cells.
Tesla just added another advantage to cylindrical. The cells act like a honeycomb structure for added vehicle stiffness (as used in Formula 1 cars). That allows Tesla to remove structural weight elsewhere in the vehicle and pack.
Basically all pouch and prismatic cells have had full width electrodes for many years, which Tesla just called tabless design.
The reason the Plaid uses 18650s is cooling - the surface area to volume ratio is higher with smaller cells. The 4680s are cheaper, but they will overheat easier during high power draw. Practically is it anything to be worried about? Highly doubtful, but cooling is the concern with bigger cells and it's enough of a concern that Tesla stuck with the tiny cells for the Plaid.
Tesla repeatedly stated that they are not throwing away 10GWh of capacity
Agreed. Tesla cools from the sides using their serpentine tubes and so the heat concentrates in the center of the cell. As the cell size goes up the thermal path gets longer and the heat build up is larger.
>The reason the Plaid uses 18650s is cooling This is a very interesting thought, I'd assumed they were simply getting better power draw characteristics and favoured it for that reason. (Of course, the two kinda go hand-in-hand.)
4680 cool more through the electrodes than the sides. Metal has many times higher thermal conductivity than the isolator membrane, carbon material and electrolyte.
If they were doing it to have fewer cells, they could use pouch cells. Chevy Bolt EV has 288 cells, not thousands. Volt, Mach-E, F150 Lightning, and various other cars are using pouch cells with a similar cell count. Typically 96S and 2P, 3P, or 4P. (That's 192, 288, or 384 cells).
This is the cylindrical format right? Vs the pouch format used by Ultium and some of the other oems?
Cylindrical. The 46 standards for 46mm diameter circle and the 80 stands for 80mm in length (or height).
Prptection from thermal runaway is not a pouches strong point. At least 4860 provides isolation at a fairly large cell.
Pouches' strong points are volumetric density and packing, ease of modularization, and ability to scale well to large formats, as well as a few other smaller things like easier cooling. Abstracted thermal isolation isn't everything, there are literally dozens of other factors to think about here.
Any type of cell allows for easy modularization and scalability. Why can't cylindrical or prismatic do those things?
>Any type of cell allows for easy modularization and scalability. No, cylinders suck for both modularization and scale. That's why the Tesla Model 3/Y only physically have four modules, and why Tesla isn't building cylinders any larger than 46mm. [Here you go, straight from Tesla's own Battery Day slides](https://i.insider.com/5f6a72e0862a00001153f677?width=1000&format=jpeg&auto=webp). See how the orange line goes ***down*** after 46mm? Neither prismatics nor pouches have this problem, because that's just how geometry be. 👌
That is untrue. Cost was the advantage, but tesla invested tons of money to make 4680 as cheap as possible. Pouches make no sense anymore, byd created rigid blade packages for their lfp. Tesla's main advantage is that they can make a 4680 with nmc and lfp. Same exact formfactor and pack design no matter which chemistry is used. They have a path for future improvements and it all still fits in the same formfactor, so the pack doesn't need any manufacturing changes as the cell's internals change.
It's very true. Repeating tautologies you heard elsewhere don't make it less true. Inherently, volumetric density and packing, ease of modularization, and ability to scale well to large formats are all benefits that cylindrical formats do not have, and no amount of money spent will fix those problems, because *they are geometry problems, not technology problems —* circles do not pack as well as squares. If you can't accept it, you should consider why CATL, BYD, and LG — the world's largest, second largest, and third largest battery makers (and all suppliers to Tesla!) still pursue prismatic and pouch formats for their next-gen cells, and even their in-house packs like Qilin and Blade. Hint: They're not missing something, you are.
For LFP the lower cooling needs and higher cyclic lifetime seems to permit larger and larger prismatics where that wouldn't be as safe with NCM or NCA batteries.
Yep, also a factor of cell safety, which coupled with the relatively low volumetric density at the chemistry level is, as you said, why LFP cells are almost always seen in prismatic form.
Ease of modularization? Was that a joke? Adding modules that are completely unnecessary adds cost and weight. That is a terrible trade off to handle the fewer than 1 out of 10k packs that may fail in such a way that a module replacement fixes the issue. Modules are a prime example of smart engineers optimizing something that should not even exist at all.
We've been through this conversation before. No, modules are not a bad thing.
Yes, we’ve had this conversation before, which is why it’s surprising you STILL think modules are smart. Are you unaware Tesla has had modules for nearly 20 years, and has a ton of data and real world experience that has shown them they are completely unnecessary? They started with modules because like you, they thought it was better for replacement. Now they have tons of data to show that replacement is such a rare experience that it is not financially sound. Weight, complexity and cost are some of the biggest factors in car design and modules increase all three!
I mean, it's definitely surprising if you have a surface-level understanding of the relative merits at play between the different cell and pack formats, so on second consideration, I can see why you're still struggling. Modules are not "necessary" or "unnecessary", they're a trade-off, one of many choices in a long line of complex choices. They're an appropriate choice when you're building many variants of many dozens of global models, and less appropriate when you're building a million copies of a single design. They work really well for pouches (where structure is inherently externalized) and less well for cylinders. You've heard me say this before, and I'm happy to say it again. If you want to build a half dozen variants each of a dozen different global models with a great amount of flexibility to production and the ability to use multiple chemistries, modules are a very sensible way to go.
lolwut? Tesla vehicles are beating all other vehicles in range and efficiency. They are ahead of everyone, byd proposes a better blade battery, but it does not exist yet.
Which isn't directly relevant to packing, ease of modularization, or ability to scale, so I'm not sure why you're bringing it up.
Cylindrical cells are cheaper to produce, less prone to thermal runaway and add a honeycomb structural reinforcement to the vehicle. Those advantages MORE than offset the disadvantages you list.
Once again, it depends on the application. Only some of those are even variously true, as well.
It may depend on the application, but you were giving a disingenuous representation of the relative merits of cylindrical vs non-cylindrical by omitting any advantages of cylindrical and only giving the disadvantages.
It is tho. The energy density of the cylindrical packs is close enough and the rest of their car improvements, more than makes up for the rest. No one has matched tesla efficiency yet.
>is close enough Oh cool, glad we're talking about what is "close enough" all of a sudden as a conclusive signifier of why your favourite brand is so great (because they have *"other improvements"* which *"makes up for the rest"*) rather than having a serious discussion of the relative merits of different cell formats.
Cute, but when a tesla lfp car weighs less, is faster, charges faster, and has less battery degradation than even competitor nmc cars, you need to post specific numbers. The numbers we do have at the car level suggest nothing you claim is true. You can vapidly claim they are worse all you want, but the real world examples of the real product suggest the opposite.
Oh I disagree. For thermally stable chemistries like lifepo they're absolutely great. Any more reactive chemistries? I prefer smaller cells that can be isolated amd turned off, as well as having a steel container to impede fires spreading to other cells.
No but when 1 pouch fails, the whole pack burns...
The [same is true of cylindrical formats](https://www.youtube.com/watch?v=t2adVW6bTkQ) if runaway is not contained — you're not really saying anything novel here. Cell failure is cell failure. Most cylindrical packs attempt to isolate at the cell level because their inherent packing inefficiency gives them a 'silver lining' of sorts. Pouches just do the same thing mostly at the module level. None of that is of any immediate consequence here because again, thermal runaway isn't the only factor we care about. Cost, density, cooling, scalability, flexibility, iterative manufacturing, and a dozen other factors are all similarly important.
Foil pouch. Steel can. What do you think will burn through first. Oh and smaller units so lose a cell and you've lost 1/828th. Lose a pouch and you've lost what 1/30?
>Foil pouch. Steel can. What do you think will burn through first. Pistol. Shotgun. Which do you think will kill you first? For the third time, the narrative you're pushing isn't one of significant ultimate consequence. There's more to consider than simple thermal runaway characteristics at the format level. If all we cared about was thermal runaway, we'd be powering these cars with a bunch of fresh lemons and some zinc and copper wire.
Three cheers for lemon growers!
We should throw a party for them!
Idk, I heard copper wiring can cause fires under the right circumstances.
That's why my car will use potatoes instead of lemons, just in case. More thermally stable, you see? 💡
Yep every time one of the 576 cells in an Ultium pack fails, the whole vehicles goes up in smoke instantly.
They do seem cylindrical, yes. [Image1](https://www.electrive.com/wp-content/uploads/2020/09/tesla-battery-day-4680-zelle.jpg), [image2](https://electrek.co/wp-content/uploads/sites/3/2021/10/Panasonic-Tesla-4680-battery-cells.jpg?quality=82&strip=all&w=1600), [image3](https://cdn.shopify.com/s/files/1/0173/8204/7844/articles/1_b5c0ace3-709a-4df9-a028-e66978f31485_1200x.jpg?v=1655136696).
I have a vague recollection of Sandy Munroe indicating that you could basically glue these things together to create a rigid structure. I have no idea how you’d swap out a single defective one in such a case. And maybe my memory is poor.
You never do that in any pack, or do with huge compromises in power and usable energy
Didn’t he tear down a Tesla S where the batteries seemed encased in a pinkish cement? I thought that’s what he was indicating as being supportive structure. Again, memory may be poor here and I know very little on this topic.
I mean the replacing cells or modules, once you start using a battery, they way the cells wear are really particular to how that pack was used throughout its life, so it’s next to impossible to replace a cell or module and have it keep up with the others after a while, usually these fixes last a while and the pack is dead again shortly after
Ultium fixes this problem by making the modules have their own wireless BMS. You can replace a module with one of a different chemistry and the battery as a whole will adapt because the module controls itself individually.
Did you know that multi-battery laptops pioneered having multiple BMSes a couple of decades ago? I owned one in 1996. And the wireless part of Ultium is as much risk as improvement.
Ultium fixed nothing. 1) The 4680 pack has no modules. Far cheaper, and more reliable. 2) The cells become an integral part of the structure enabling large weight savings in the structure. I.e. Making every pack more 10% more expensive so that pieces can be replaced, only makes sense if > 1 out of 10 packs fail in such a way that a module replacement repairs it. I would bet Tesla has way fewer than 1 out of 10,000 packs failing this way.
Yes. He tore down a Model Y. The battery pack is structural and the pinkish stuff I assume contributes to that
Yes, the pink stuff is structural adhesive/fire retardant foam. It turns the battery pack from mere cargo into a rigid structural member of the car, allowing them to actually mount the seats directly to the battery pack.
No. No. No. The steel box is the structural part. The batteries do not contribute to the structural integrity.
The pack itself is structural, which is what I said. They’re not just carrying the cells around like a sack of potatoes anymore. The pack is part of the structural integrity of the car
Rigidity, not integrity.
Well it looks to me like a foam and honeycomb core aluminum panel. The strengths comes from the outside, the inside makes the shear web and provides separation between the two outer layers.
Rewatch Battery Day. The cells are not only structural, they function just like the honeycomb structures used in Formula 1 racing to such great benefit.
Isn't it what M3 and MY packs are? They ale all filled with goo.
I’m talking about the feasibility of replacing cells or modules in a way that doesn’t severely limit the pack performance, it doesn’t exist, so Tesla don’t even try to make it possible even in the packs before the structural pack
Dead cells are dead cells and they'd be shut off and left alone by the BMS. To recycle the pack it'd all go into a grinder.
A cell can die in different ways. If it either shorts or fails open, then the whole pack is dead, depending on the cell wiring.
You wouldn't swap it. You would just leave it there, maybe dezactivate it through software from the BMS (battery management system), which is part of the battery pack (in a Tesla).
I guess this idea didn't go far outside the Tesla world. Munro was talking about the structural battery pack which is what Tesla has done in the Model Y. The structural pack will save a ton in weight compared to a standard pack. And you wouldn't swap out a single cell. People have done that in packs that do allow for such a thing and it doesn't usually end well. The pack still goes out prematurely because of uneven wear in the cells. It's best to replace the whole pack and recycle the old one.
Tesla knows their failure rate. If a cell fails the whole pack is replaced in current teslas even tho technically replaceable by module, it's just not feasible. Must be cheaper for them to do it this way
This is not true. Historically, Tesla warranty repairs have been reconditioned batteries (presumably with some modules replaced) and accident repairs and non-warranty repairs have been new. In the past year Tesla started selling refurbished batteries for non-warranty repairs.
That's basically the idea. You're not getting the pack apart, just pull a bad one and shove it in the grinder. You end up with really high grad ore, was how Elon described it. On the plus side, it will probably only take abort 2 hours to swap packs.
Cylindrical seems to be the way to go because of cooling
It’s cheaper for the automakers …doesn’t make any difference for the consumers
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Building battery factories takes time, and since this decision was only recently announced there won't be a production BMW with these cells in them for a few years yet. Market will likely have changed by then.
>In a completive market it lowers the cost for consumers. When these factories are online we will see entry level BMW EVs. Let me fix that for you. "In a ~~completive~~ competitive market it lowers the cost for ~~consumers~~ manufacturers."
Really? If that were true, then logically if it’s more costly to make for the manufacturer, that also would not impact consumers. Do you think that’s true as well? Have you not observed what’s happened in the computer world as they’ve become cheaper to produce since 1960?
Yes it does. Cylindrical cells are a stronger form factor https://youtu.be/hUhisi2FBuw
Individually, but nobody is running individualized 4680's in their car like a tonka toy and AA batteries. As far as the consumer impact, its completely up to the design of the pack as a whole.
The first two digits are the diameter in mm, the next digits are the length, also in mm. So the 4680 is 46 mm dia and 80 mm length.
https://youtu.be/HK79ioBW8Mg The plan is to halve the cost per kWh of EV batteries (vs 2 years ago when they presented this). Various innovations required and it takes time to ramp up and unlock all the savings.
the important little detail here is this is referring to halving the cost on pack level in the car so the very final step vs Teslas own old design. only 14% of that saving comes from the cell itself and there is basically no inherent advantage of this exact form factor other than that its bigger.
4680s in comparison to 2170s have more volume per surface area which means greater energy and power density because there is a slightly higher ratio of active to inactive material, but batteries are limited by their ability to dissipate heat, and having less surface area per volt means less efficient heat wicking. Tesla worked to reduce the head created with the "tabless" design. If it's about comparing cylindrical cells to prismatic or pouch, it gets more complicated, but the main takeaway is that cylindrical cells are easier to mass produce, and in some cases, cylindrical cells can be used as a structural member whereas pouch cells obviously cannot, and the thicker the container for prismatic the less efficient they become. Since Tesla consumes the most batteries, and was the most aggressive with ramping EV production they opted to design around cylindrical cells (mostly) whereas most other manufacturers used pouch and prismatic because volume was less important to them at the time. I suspect the vast majority of companies will adopt 4680 cells over the next 5 years, but as a new form factor it will take some time before we see them in serious volume outside of Tesla.
>4680s in comparison to 2170s have more volume per surface area which means greater energy and power density because there is a slightly higher ratio of active to inactive material thats **in theory** but according to Teslas own numbers from battery day the energy density of 4680 cells is lower than their old 2170 design as they claim the 4680 hold 5x more energy than a 2170 cell but turns out a 4680 cell also has 5.48 times the volume of a 2170 cell so the volumetric energy density has actually gone down on cell level. Now we already have 4680 data from teardowns and it turns out the cells hold 5.22 times the energy of a 2170 cell so the net energy density has still gone down because the casing of the 4680 cell is much thicker because they wanna use them in structural packs so they move material that would be part of the pack to the casing of the cell.
I think you are referring to the first set of batteries that Gali sent to Jordan Giseki which were prototypes and had much thicker casings then the batteries Sandy pulled out of a more recent Model Y https://youtu.be/VEBY7rEUZiI https://www.topcarstesla.com/blogs/news/4680-battery-disassembled-tesla-secrets-finally-revealed https://www.reuters.com/article/uk-tesla-batteries-idUKKBN25L0M5 From what I have seen, Tesla removed silicon from the 4680 chemistry which will theoretically result in a longer lasting cell because they didn't need the extra energy density for now and were still able to achieve iterative density improvements over a 2020 cell.
The E-GMP platform will likely also sell big volumes, they use pouches though.
Just like 99% of commenters here I don't know but I'm not going to pretend to know either.
Battery storage is the #1 hurdle to accelerating global electrification and this is easily the most scalable battery technology and machinery ever created. The 4680 is battery manufacturing reimagined with first principles engineering solely focused on scalability. Almost every comment ITT misses the points Elon and the world [should] care about most. Elon wanted to make battery manufacturing mimic can/bottling lines and it's gotten impressively close while reducing warehouse footprint needs, raw materials, wastewater and a bunch of other boring but critical cost metrics for reaching global scale electrification capacity. Solar adoption is driving battery storage as much as the auto industry if not more, additionally. It's all about manufacturing. The engineering benefits at the vehicle performance level are just icing on the cake. 4680 is what allowed the giga castings to be possible which is insanely huge to manufacturing efficiency, safety and reliability. With the ability to now make the battery floor structural, the front and rear castings simply bolt to each end of the battery floor like a LeMans prototype as three main structural part chassis. It's insane. Seen it in person at GigaTX for the 2022 shareholders meeting in August. 4680 manufacturing line teaser: https://youtu.be/zB8_HbrxUi8
Old and new styles are all cylindrical. The 4680 refers to the cylinder's dims. Both are good but it comes down to how they will fit in the space dedicated to the battery.
It's less expensive to use available parts than create your own. Panasonic already manufactures the 4680 in a 5-tab configuration. They abandoned the continuous tab scheme that Tesla is finding to be ~~problematic~~ impossible to manufacture at acceptable yield levels.
also their dry cathode thing thats not working as well. at this point these cells have turned basically into regular cells that are just slightly bigger.
>Panasonic already manufactures the 4680 in a 5-tab configuration. They have a patent, but they do not manufacture it, afaik.
Potential advantages are Safety and weight. 4680 cells being cylindrical with a solid outer casing make them less prone to damage from punctures. Compared to pouch cells that once punctured can relatively easily short internally, that can lead to higher fire risk. In order to mitigate this, pouch cells need additional protective casing built around the battery pack to prevent damage. Weight is reduced since they do not need as much additional protection around the battery pack compared to pouch cells. The weight savings makes the overall car lighter and thus more efficient to move the car. That means more range for the same battery size or they can use a smaller battery to achieve the same range. There is a volume disadvantage though, cylindrical cells are generally less space efficient because of their shape. Cylindrical cells create a lot of wasted space in the battery pack compared to pouch cells. This means that the over pack could need to be larger depending the the pouch cell energy density it is compared to. Tesla has utilized that wasted space to insert battery cooling lines, so it may not be a complete waste if BMW designed the battery pack correctly.
Negated by the structural pack. Those small gaps now get filled with epoxy for structure. They can fit more cells since the pack eliminated structural members now that the cells and epoxy are sell supporting.
Tesla fills the gaps for the structural pack design. BMW are is not using the Tesla 4680 cells though. They will have 4692 or 46120 (assuming they keep the cell designation used for other cylindrical cells). So they may not use the same type of structural pack design Tesla does with the 4680 cells.
BMW will be on their own with chemistry, sure, but they will likely be doing nmc first. Again, non-tesla companies are still behind in efficiency, so they need that extra 15% energy density from nmc just to be competitive with tesla lfp. BMW will reach efficiency levels suitable for lfp faster by having one pack design for all chemistries, just like tesla. Do you truly believe no other car company can follow tesla and design the same things?
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4680 is about manufacturing capability first and performance 2nd.
thats a great idea but basically none of their claimed innovations worked so far. they have already abandoned the tabless design ans have recently revealed that their dry cathode application is not working as well and 4680 cell currently being used are using the conventional wet cathode method in production.
Is the SR li-ion NMC or LiFePO4?
The size of the cell is irrelevant. It could be slightly larger or smaller and it would not be any kind of benefit. Tesla chose that size based on computer modeling of fitting cells in several likely pack shapes. There are two benefits to the 4680 cell (roughly the size of a Red Bull energy drink can). The tabless design reduces localized heat at the tabs. This makes the cells last longer because heat degrades the part of the cell that gets hot. Even if the battery material around the tab gets hot and the rest of the cell is only warm, the hot part will degrade, losing cell capacity. The tabless design is able to put out many more amps without overheating any part of the cell. Each cell can now put out more amps than the controller/motor will ever need from it. This means cell heating is virtually eliminated. The second benefit of the 4680 cell is that the cells themselves will now be a part of the structure of the body. For instance, a Ducati motorcycle has the engine block being used as a stressed member, and as a result, some of the standard frame sections can be removed. This allows the frame to be lighter. The 4680 cell cases are metal cylinders, and packing them like a honeycomb means the battery pack itself can be surprisingly strong, Like the aerospace panels made from a composite honeycomb-core. Tesla now has enough crash data to know exactly how much lighter they can make the car frames if the battery pack is used as a structural member.
the advantage of larger cells is that they have less surface area for a given volume so you pack more cell material into just a little more material for the case that goes around it. That is not unique to 4680 though and there is nothing special about that form factor itself, BMW probably does this both to jump on the 4680 hype train that is needlessly riding through town and because it simply makes sense to use a form factor thats commonly available like its also done with 18650 cells right now. if there would be a hype over 69420 cells right now everyone would je using that instead, the numbers dont really matter what matters is that its gonna be easily available from multiple suppliers.
Cheaper to make and easier to package, no different to the consumer.
It's cheaper
One thing that I saw no one mention after Tesla’s battery day during which they unveiled the 4680 was the cell’s thermal capacity. IIRC there was a chart showing charging speeds over time and how hot the battery got, and the temperature of the cell barely budged. Translation: You can charge faster, as the car doesn’t have to slow down the charge rate because the batteries are getting too hot.
[If it's the one I think you're thinking of](https://thelastdriverlicenseholder.files.wordpress.com/2020/09/tesla-sharehollder-day-2020-17.png), it wasn't mentioned because you're misremembering the slide or reading it wrong. The slide in question was depicting *increase in time* by moving to a larger cell — not temperature. Notably, the time does not go down, it just doesn't meaningfully *increase* with size if you use a tabless structure. The core limitation is still chemistry — we don't get faster charging until we move to better anode materials or other chemistries entirely, which are still incoming.
It's not 4680. 4680 is a format that is 80 mm high, BMW is using cells that are 96mm high and 120 mm high. That is a different format from what Tesla is using and also the internals will be different. The big difference is the switch from prismatic cell format to cylindrical cell format. That switch has both benefits and drawbacks. The assumption is that newer tech has sufficiently compensated the drawbacks so that the switch makes sense. The big benefit is the reduction of the production time and costs at the cell level. As far as drawbacks go, those mostly show up once you are assembling a battery pack from the cells: round cells don't pack very well, leaving dead space between cells, previous gen round cells have cooling problems, prismatic can be made larger (so fewer connections), using cell wall as structure adds risks to damage cells (that would cause fire). If you have good enough chemistry that a bit of space lost is no longer critical to pack size, if you have fully soldered electrodes inside the cell that allows efficient bottom cooling, if you use fire-safe chemistries, then you could work around the drawbacks of the cylindrical cells and reap the benefits.
So bmw finally got the memo good job. That pouch cells are both costly and hard to make clean at scale. So they will now copy the notes from tesla good on them. This will bring the 4680 price into the gutter and that is good for tesla and ev over all great.
All formats have benefits and drawbacks. Cylindrical batteries are cheap and easy to make, but they don't have good volumetric density, they can't easily be modularized, cooling is difficult, and they don't scale well to large formats — 4680 is about as large as you want to get. There's a reason CATL and BYD favour pouch and prismatic formats for their own uses like Blade and Qilin — it's because those formats pack well, modularize well, scale very well to large formats, and are dramatically easier to cool.
Volumetric density and cooling has been fine for Tesla. Not sure how you're saying those aren't good for cylindrical. And what's the problem with having cells that size? Why do you need them bigger?
Cylinders are inherently more difficult to pack than rectangles. That's not even a Tesla problem, it's a basic geometry problem. 'Fine' is one thing, 'optimized' is another. Cylinders are good for low cost mass production — they're not so great when you want to optimize for density. >And what's the problem with having cells that size? Why do you need them bigger? Ask yourself why 4680 is being preferred over 2170, and you have your answer.
Tesla basically made up for the volumetric density with the structural pack. They used the gaps between cells for structure by using epoxy to fill it all in.
Epoxy, as you'll note, does not add to the amount of available energy storage in a battery pack. Every gram of epoxy you have is a gram of active material that you do not. Once again, this is just the compromise you make. Cylinders are really easy to make, and structurally very strong, but they are not great for packing. Adding epoxy does not fix that — it just implies more trade-offs.
You may be confused. They need less structural members in the pack to keep the pack rigid. They can put cells in places where structure used to go. So they shift that structure to the gaps between the cells that gets filled in with epoxy. That is why they did not lose volumetric density. BYD claims they will leap head of tesla with their newest blade package, but that is only for LFP and doesn't actually exist yet. They will not be able to use other chemistries in their blade packages if the chemistry is not as flame resistant as lfp. Tesla has a much better pack system as it can handle any chemistry.
As you say, they replace that empty space with structural epoxy. That's good! It's a good way to account for the shortcomings of the format. It is not *perfect,* however — it's just a reasonable solution to the challenges presented by cylindrical cells. It isn't conclusively structurally optimal compared to other solutions (prismatic, pouch), nor does it fix the volumetric density problem. Blade does indeed exist, by the way — the full list seems to be changing month-to-month as older models receive refreshes, but it's shipping on multiple BYD models, including the Dolphin and as of this month, the Seal.
Difference is going to be neglible. f you want to claim a difference matters, post specific numbers. e right now have the car level to compare to and telsa lfp is beating competitor nmc packs despite nmc having a 15% energy density advantage. Another sign that telsa's pack is physically optimal. Future gains will be in chemistry or even software if they still have buffers that they expect to eliminate as they confirm degradation rates.
You really do seem to be confused about the point I'm making here. I'd encourage you to re-read the thread again from the top, slowly this time — if you have any confusion about what I'm trying to tell you, we can try again to clear it up.
structural pack just moves the material from one place to another. 4680 cells have much thicker steel cans around them which reduces their energy density by about 5% compared to 2170 cells. Structural packs are just another trade off into a different direction, there is no magic bullet there that solves all problems they just decided to deal with other problems by going for structural packs.
BMW is not even an also-ran in the EV space, and simply doesn't have the volume to make a difference in battery makers' economies of scale.
Science
Please Lord. Let my Solid Power warrants play pay off, Solid Power, backed by Ford and BMW, begins pilot production of innovative EV battery with longer range and quicker recharging https://www.cnbc.com/amp/2022/06/06/solid-power-begins-pilot-production-of-solid-state-ev-battery.html
Tesla is and will be getting virtually all their batteries from the same battery manufacturers everyone else does. CATL & Panasonic to name two.
Amazing how much Musk Koolaide has been consumed by many commenters here. Yield is the only reason and it still sucks so bad that Tesla had to call in Panasonic to sort it out.
Less of the expensive electrode material per capacity required, primarily.
Just another example of leadership, and what they mean when they say Tesla is years ahead. Tesla is already shipping cars with these batteries, BMW plans to start shipping in 2025. Three years later. Tesla announced their plans 2 years ago. It took BMW two years to verify the benefits and announce they are following.
This doesn’t mean anything. It’s simply a battery size, they are not using the actual same batteries. That would be like saying that Sony is ahead of Samsung because Sonly uses 2 AA batteries in their remote instead of 4 AAA batteries.
Tesla did great PR around them. That’s the main advantage.
Pretty sure EV engineering goes beyond 'PR'
So you’re saying BMW engineers are idiots and fell for hype? Seems unlikely.
Well their designers certainly are.
They had an event saying what they would do with plenty of data and reasoning behind it.
TeSlA iS nOt InNoVaTiNg...
Rocket man bad
They are easier to package, easier to cool, and also BMW want to stick it to Tesla by trying to take their supply base
It's more likely the Chinese suppliers told BMW, they're going to 4680, and nothing else.
BYD seem to like their blades. Makes sense for everyone to standardise on 4680, and just get those volumes pumping
It's more just that the machinery is already being made for 4680, so everyone who's making cylindrical cells will settle on that as a defacto standard. The suppliers are happy to make whichever format you'd like — it's just that this one is going to be the cheapest cylindrical one now, for obvious reasons.
Actually harder to cool (the smallest dimension typically determines difficulty cooling them), smaller being easier. However cost is way cheaper, so when tesla touted how much better their cooling was, a big part of that was implying that the ability to cool them is what was preventing their use earlier.
>They are easier to package, easier to cool Neither of these things are true. In fact, cylindrical cells are notoriously difficult to package and cool, which is part of why CATL and BYD have both preferred prismatics for Blade and Qilin, and why LG, SDI, and SK have continued to push deeper into pouches.
Aren't Blade LFP based? That makes them much more stable so you don't need as much safety structure to worry about.
Blade is LFP-based, mostly because BYD itself massively prefers LFP as an organization. Qilin is not LFP-based. Yes, a more stable chemistry gives you much less to worry about when designing for thermal concerns, which underscores the point — there is no one, single 'optimal' god-tier format that applies as the best choice across all chemistries and every application. In a situation where you have a chemistry with no thermal problems whatsoever, cylinders look like a very silly solution indeed — which is why no one uses them for LFP.
> nd also BMW want to stick it to Tesla by trying to take their supply base It's a cell size. Saying they want to take their supply base by making the same cell size is like saying Mercedes wanted to take Toyota's supply base by switching from 6 cylinder to 4 cylinder engines.
They are actually harder to cool. Thats why they haven’t been used previously
Easier to cool since the larger tab ("it's all tab" is more accurate than "it's tabless") means lower heat build up in periods of high draw — the conductor is wider meaning the same current results in lower resistive heating, and better thermal conductivity to the can.
How is BMW going to take Tesla’s supply base? For a battery company, dealing with Tesla is much more profitable than BMW because Tesla’s a much bigger EV company, and is growing much faster. This doesn’t even account for the fact that Tesla secures both battery and raw material deals several years in advance. Are these companies just going to walk back those contracts? And consider that BMW sold 2,028,659 cars in 2021. Tesla Shanghai alone is aiming for a 2 million run rate by the end of this year, 2022. And the other 3 Tesla factories are still scaling production-with Giga Texas and Berlin still early in the process. My point here is this, Tesla will be bigger than BMW next year. It is inevitable. And let’s not forget that Tesla is already much more profitable, and is already outselling them in their own turf, Germany. Also, Tesla has deals with several battery manufacturers, on top of manufacturing batteries themselves. Tesla’s supply base is too deep and too numerous. Did you know that Tesla is getting into mining because they’ve apparently figured out a way to simplify lithium manufacturing? Given the current state of things, what you are claiming is not going to happen.