Tesla 2170 Battery Cells: Greater Power At Comparable Cost

4 weeks ago by EVANNEX 75

Tesla 2170 Cells


It sounded like a crazy idea back in the early 2000s, using “laptop batteries” to power the Tesla Roadster. In fact however, it was quite sane. Panasonic’s 18650 battery cell was an industry standard with a proven record of performance that was being produced in large numbers. While other EV pioneers such as Fisker ran into problems with proprietary battery technology, Tesla could count on a secure supply of tried-and-true cells. Since then, Tesla has steadily improved the cells, but it stuck with the 18650 format (named for its size: 18 mm in diameter and 65 mm high) for Models S and X. While other EV-makers opted for larger pouch-style cells, Tesla continued to see the 18650 cells as the most compelling option.

*This article comes to us courtesy of Evannex (which also makes aftermarket Tesla accessories). Authored by Charle Morris.

“We’ve totally custom-engineered that cell, working jointly with Panasonic to create…an automotive cell, tested to automotive standards,” Chief Technical Officer JB Straubel told the Society of Automotive Engineers (SAE) in 2013. “It doesn’t go into laptops anywhere. What keeps us in that general shape and size is the production and cost efficiency. We’re seeing price points that none of the larger-format cells are able to meet.

Older/current style 18650 Cells

However, all good things must come to an end. Tesla and Panasonic have now developed a new and improved type of cell, which will be used in the upcoming Model 3. The new 2170 cell, which is now being produced at the Gigafactory, is slightly larger – 21 mm by 70 mm. More importantly, it can store a lot more energy. According to Elon Musk, it’s “the highest energy density cell in the world, and also the cheapest.” The 2170 cell is around 50% larger by volume than the 18650, but it can deliver almost double the current (the 18650 delivers 3,000 mA, and the 2170 has been tested at 5,750-6,000 mA).

Above: Inside the 2170 battery cell (Youtube: Portable Electric Vehicle)

Tesla hopes to produce these new, larger cells at the same cost as the old cells, which means a reduction in total battery cost. It’s also assumed (though Tesla won’t confirm any numbers at this point) that the battery chemistry has been improved, yielding a higher energy density. Producing the cells in mass quantities at the massive Gigafactory will allow Tesla to achieve economies of scale.

Above: Comparing the 2170 and 18650 battery cells (Youtube: Portable Electric Vehicle)

Adding all these factors together, plus advances in the way the cells are assembled into modules and complete battery packs, should yield a significant reduction in battery costs. But how much? This question is being discussed at great length, and not only by techies. It’s of great importance to stock market analysts, because it’s bound up with the question of how much profit Tesla is going to be able to make on the “moderately priced” Model 3.

Stock pundit Randy Carlson of Seeking Alpha (usually a forum for diehard Tesla bears) has gone into excruciating detail about the thickness of Model 3’s floor, reasoning that whether the battery cells are mounted vertically (as in the Model S/X battery pack) or horizontally will yield some priceless insight into how great an improvement in energy density Tesla and Panasonic have been able to achieve.

At the Model 3 unveiling, Tesla showed a drawing with eight large, flat battery modules, but offered no details about how the cells would be arranged within the modules. “If we know [the thickness of] the floor of Model 3, and we know its range, we will have a pretty good idea [of the efficiency of] the GigaFactory cell chemistry,” writes Carlson.

*Editor’s Note: EVANNEX, which also sells aftermarket gear for Teslas, has kindly allowed us to share some of its content with our readers. Our thanks go out to EVANNEX, Check out the site here.

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77 responses to "Tesla 2170 Battery Cells: Greater Power At Comparable Cost"

  1. unlucky says:

    There’s no way a cell with a steel shell is the highest energy density cell in the world or the cheapest. Pouch cells are higher density, that’s why everyone uses them, and I don’t just mean in your car. Look inside your cell phone.

    This is a good improvement for Tesla but I just can’t understand why they stick with such small cells. Packaging material goes up slower with increasing size than volume does. Bigger just is plain better for density and costs, as we see here. I can’t see why this would be anywhere near optimal size for a vehicle with suck a large battery capacity.

    1. GeorgeS says:

      I tend to agree that prismatics package more efficiently. However. The steel case allows for more internal ptessure than a pouch cell plus the added safety factor for the steel case (fire and crash safety).

      So it may be the case where the cylindricals can hold a more volatile and therefore more energy dense internal chemistry than prismatics….just speculating here though.

      Either way the cost factor tips the scale in favor of cylindricals.

      1. Mint says:

        That’s an excellent point. Cars go through a lot more regular vibration and structural flex than portable electronics, so strength and ability to maintain a perfect seal have higher importance.

        In the end, though, Tesla has already shown that volumetric density alone has been good enough for at least 5 years. Cost is the limiting factor, and it’s obvious throughout industry that rolling up thin films (plastics, papers, foils, etc) is much cheaper than layering them in flat packs.

    2. David Murray says:

      Tobe fair.. the reason pouch-style batteries are used in the phones and tablets has to do with the shape more than anything else.

      1. Pushmi-Pullyu says:

        Exactly. Cell phone cells need to be flat because cell phones are flat.

        And just because pouch cells are more compact doesn’t necessarily mean they’re better. The cylindrical cell has a metal case (or “can”) which needs little additional structural support when assembled into a pack. The pouch cell has to be put into a frame to keep it from flexing or moving around. So when it’s assembled into a pack, is there really any advantage there? Sure, you can cram pouch cells in side-by-side in a smaller space, but that means a much greater problem with heat buildup.

        There are advantages and disadvantages to all the different form factors. I don’t think we can say that overall pouch cells are “better” than cylindrical cells. It really depends on the application.

      2. unlucky says:

        For any given volume you can inscribe one or more cylinders in it. So why did laptops and phones stop doing so decades ago? To get better space efficiency. Why not a Tesla?

        Heck, is not the battery pack in a Tesla similar in proportion (of course not size) to your smartphone when it is laying on a table? Why is cylinders the right shape for one and not the other it doesn’t make sense from a volumetric perspective. I do agree with GeorgeS that it could be that the fact that a cylinder uses less material for the same swell/burst resistance could come into play. I just don’t see how it would dominate over the space and weight savings of not having all that extra metal in there.

        Pushy: I didn’t say one was always better than the other. I’m talking about a specific application. Tesla’s application. And Tesla does not use the strength of the cels for trees of the structural function of the pack.

        And while you don’t want a pouch cell to move, there’s not actually a problem with it flexing. You need the top and bottom to remain relatively fixed but if the center changes shape a bit it’s okay. And it does cells swell a bit with age and as GerogeS says above they do swell more than something in a steel cylinder would.

        Just from a pure cost perspective I don’t get it. All that added steel, a thousand cylinders worth. Plus the steel to support the weight of that steel. It is quite a bit of weight and cost.

        If 15% less steel is better (2170 vs 16500) why not another 15% less? Or whatever the actual ratios are?

        Imagine the amount they spend on steel on Powerpack. When swell space would be virtually free (size isn’t all that important).

        1. Pushmi-Pullyu says:

          You’re ignoring the added complexity of assembling pouch cells into packs. As I recall from what I’ve read of Leaf pack assembly, they take two cells and put those into a frame, then they take that frame and put it into a rack. All that surely takes time and adds to the expense of assembly.

          Contrariwise, the cylindrical cells Tesla uses are simply held in place by a plastic sheet with dimples in it, one dimple per cell. One sheet on the top and one on the bottom of the cells, and you’re done.

          Furthermore, I’m not at all sure the assertion(s) here, that pouch cells have higher energy density, are true. When the Model S first debuted, Tesla was using higher energy density cells than anybody else, which is one reason Tesla was able to put such a large capacity battery pack into the Model S.

          It was often said that other auto makers used lower energy density cells; they used larger cells with cheaper chemistry, which should have lowered the per-kWh cost of the cell, but apparently didn’t. I don’t know if that’s still true or not.

        2. Michael Turner says:

          Laptops still use cylindrical cells… Maybe some have switched for form factor reasons, but I suspect that is the only reason any would change.

          Anyway a big reason for tesla sticking to cylindrical cells is their investment in temperature management systems. They designed them around cylindrical cells for the model S. Each cell touches the liquid cooling system. There is enough surface area on each cell for the temperature to be controlled effectively. Now consider how you could do the same thing with pouch cells. Your cooling system grows massively as a result, and maybe you can do something but it requires a complete redesign. Scaling up the cell size means they can continue using the same core temperature management system.

          1. Windbourne says:

            Ah. An engineer.
            Tesla is all about thermal control as well as manufacturing.
            With those small cells, they are able to keep the cells incredibly cooled even when doing a launch. OTOH, the flat paks are very large and have smaller surface 2 volume. As such, hard to guess the center temps, let alone control them.

        3. Mint says:

          What on earth makes you think pouches need less packaging material?

          Cylinders have far higher strength-to-weight ratio than pouches, and far lower surface-to-volume ratio.

          Besides, cost is by far the most important factor, and steel costs less than $0.5/kg. Even if 5% of the cell was steel (it’s surely less), that’s 0.4 cents of steel per $2+ cell. Form factor affects cost in so many more important ways than that: cooling, safety, strength/seal, production machinery cost and maintenance…

          1. unlucky says:

            What makes me think this? That it is true. Laptops don’t use cylinders anymore. They use prismatics. Cylinders are efficient shapes until you need to pack them into a space, then they waste space because they don’t pack tightly.

            A Bolt has 288 cells a Tesla model S 75 has 5,000. Even if a single. Pouch has more material around it than a single 18650 surely you can see that the Tesla pack will have a lot more cell wall material.

            1. Mint says:

              It’s NOT true. You think it is because you compare apples to oranges in an effort to support your crumbling claim.

              If you made an equal volume cylinder (of reasonable aspect ratio) with walls as flimsy as a pouch, it would use less material. This is indisputably proven with grade school math.

              18650’s aren’t out of favour for laptops and phones due to packaging cost. They’re just too damn thick.

              The form factor of a laptop or phone has nothing to do with that of an EV.

              Space waste of cylinders is negligible for an EV battery pack, because prismatic cells need space between them anyway for coolant to flow.

    3. Nix says:

      Tesla’s engineers are continuously evaluating different batteries. As better options become available, they will continually improve.

      If pouch cells were the winner of all the various factors that they consider, they would have used pouch cells.

      Their attitude towards new battery technology is that if somebody has a great battery, bring some production test cells and they are happy to test them.

      There also happen to be advantages to smaller cells. Such as the ability to get more coolant surface area to faster cool the cells. Surface area plays a big role in heat transfer capacity. So a pouch cell that might work perfectly fine in a low performance, slow charging rate EV, might not work at all in a high performance fast charging EV.

      But I’m sure you know better than Tesla’s engineers…..

      1. DangerHV says:

        “But I’m sure you know better than Tesla’s engineers…” You were much nicer to unlucky than I will be.
        Unlucky, You are so brilliant in battery tech, you must submit your resume to Elon and replace J.B. immediately! Tesla needs to be shown how to do things right! (your way, of course).

      2. unlucky says:

        You assume that their engineers had free reign. Usually engineers are given constraints to work within. If Panasonic only makes cylinders would engineers be told to consider pouches? If Musk demands cylinders would engineers be told to consider pouches?

        You make an assumption about the situation so that you can wrap up with a convenient insult indicating that I could not have possibly considered that Tesla’s engineers have brains too.

        But is it possible the person who has not considered the situation is you? When a person reaches the answer on Wheel of a Fortune before the contestants can it not be because they are freed from the constraint of waiting their turn to act? It doesn’t have to be that the person at home is smarter.

        1. Pushmi-Pullyu says:

          Since you’ve chosen to make this about personalities rather than fact, Unlucky, I’ll point out that you are rapidly developing a reputation for making up your mind and refusing to be confused by the facts. For example, your repeated attempts to refute the reality that Gigafactory 1 will free Tesla of any constraint on production of its cars due to battery supply, while other auto makers — those which don’t control their own battery factories — will be production constrained.

          Tesla has a very sophisticated battery analysis lab, and they do a great deal of very thorough testing of different types of cells available from different battery makers. If Tesla is sticking with the cylindrical form factor cell, then it must be because Tesla sees some practical advantage to it. Your attempts to cast doubt on this reality by suggesting that it’s just Elon being stubborn… well, Elon’s not the one being stubborn here. It’s you.

          1. ¯\_(ツ)_/¯ sven says:

            Ain’t that the pot calling the kettle black!

          2. unlucky says:

            Even a gigafactory has a fixed output. The idea that Tesla cannot be supply constrained on parts (including cells) is just ridiculous. Again, just because they make cells in the same building doesn’t mean they can scale without restraint.

    4. Ambulator says:

      “This is a good improvement for Tesla but I just can’t understand why they stick with such small cells.”

      Just look at what BMW is achieving with pouch cells. 80 Wh/kg now and hoping to get 200 by 2025. Tesla’s small cells were somewhere around 260 Wh/kg initially, and possibly better now.

      1. agzand says:

        With current 94 ah cells the weight/kwh difference is about 25%. If BMW switch to 120 ah cells their pack will be about the same weight/kwh as current Tesla pack. So the difference is not that dramatic. Also for a larger pack they can drop the weight, it is not linear.

        1. John says:

          Smaller cell size gives a lot more versatility in packaging.

          Powerwall, Powerpack, cars, trucks, tools, etc.

          They have a lot more options this way.

    5. Alonso Perez says:

      Thermal properties are better with a smaller cell, the cells are more robust, and a cell failure has a lot less impact.

      All three of those parameters get worse with increases in size.

      1. Pushmi-Pullyu says:

        ^^ this.

        With larger pouch cells, the failure of a single cell may reduce a pack’s capacity by as much as 1/2 a kWh. With the thousands of small cylindrical cells Tesla uses, losing just one is hardly noticeable.

    6. przemo_li says:

      Ohters go with pouch style, cause they do not have whole floors to spare.

      On top of that Tesla had Panasonic to buy from and Panasonic had lots of equipment for round 1867 cells…

      Still, Tesla+Panasonic could go any route for Gigafactory. Bigger but still round cell format sugest it’s really best for the scale and use Tesla+Panasonic have in mind.

      1. unlucky says:

        Bolt had a floor to spare. Used pouches.

        1. Windbourne says:

          Exactly right. GM choose pouches which means the bolt does not have the performance on acceleration or charging.

          Worse, you have to use large numbers of cells for driving and charging. With 8000 cells, you can use smaller fractions.

          And finaly, lose a pouch, u lose .5% (200 pouches ). Lose a cell, and it is 1 in 8000.

          Quite the difference.

    7. pjwood1 says:

      ” I just can’t understand why they stick with such small cells. ”

      That’s OK. As a consumer, I still wonder why others stick with such small packs.

    8. Murrysville EV says:

      Small cells permit more flexibility in packaging the whole car, and in tuning the total pack capacity.

      Perhaps some day the packs will no longer be a large flat slab, but will be a variety of sub-packs dispersed throughout the car. Small cells would be quite amenable to such an approach.

    9. speculawyer says:

      I think you might need to study some geometry.

      Cylindrical reduces cell casing material compared to pouch. Yes, Cylindrical introduces some wasted space between the cells…but this turns out to be a feature not a bug because it provides a place to have coolant flow past the cells.

      1. unlucky says:

        I think you might need to study up on packing. A cylinder is better if you have just one and no constraints on the dimensions. If I have a truck to fill with liquid will I get in more liquid if I pack it in cylinders or if I pack it in juice boxes? The TetraPack company already figured this out for us long ago.

        1. Pushmi-Pullyu says:

          I think you might need to start considering what others are saying, instead of just arguing with them as if learning is a zero-sum game for you.

          Speculawyer is correct.

          1. unlucky says:

            Learn something sometime. Jeez. Learn about packing. Here is a fun video to start with.


        2. Mint says:

          Tetrapaks don’t need coolant flowing around them.

          Tetrapaks aren’t filled with a solid that is cheaper to roll than to stack in sheets.

    10. love_my_models says:

      There’s a few things going on here. One is “density”. Density is measured by volume or by weight. The “highest density” claim of the cylindrical cell is by volume, not weight.

      Tesla originally choose the cylindrical format mostly because of cost and performance. The format was already widely available for cheaper than prismatics. Having a smaller cell also means they can charge/discharge quicker. Having smaller cells also means better temperature management; this also translates into better charge/discharge performance.

      Since they were designing the car for the cell format, they could use the packaging to their advantage.

      The decision to stick with cylindrical is because of the same trade-offs. Tesla has decided they can make cylinder cells cheaper, denser by volume, with higher performance. Even though it is heavier, you can ultimately cram more power into a car with cylinders than with pouches.

      You may note that Teslas are not particularly efficient compared most other EVs. Much of this is the higher weight of the cylinder format. Tesla has decided to take the hit on weight; and market towards the better range and performance that is achievable with cylinders.

      (disclaimer: I f’ing love my Model S)

      1. unlucky says:

        Tesla originally selected the cylinder because they were a broke, unproven company who claimed it would a lot them to use commodity cells. Tesla could order 18650s without having to enter into a huge supply contract because Panasonic could make them with little upfront cost since they were already making a lot of them for other companies. In a supplier contract the supplier will fold the up front costs into the unit costs by amortizing those costs across the minimum number of cells you can guarantee you will buy.

        Since Tesla could not guarantee a large number of sales they would have a small minimum in their contract and so the upfront costs would show up disproportionately much in the per-cell costs.

        So they minimized their cell costs and thus total cost per unit capacity by using cells that required little engineering cost on their supplier’s part. Now that they can guarantee a high number of sales using a custom design (as we see here) makes financial sense. The extra per cell cost up from up front costs us more than absorbed in the reduced cost of production per unit energy.

        The question I ask is why if you are going to make a custom new design do you not make the cell much bigger driving down the price of the cells on a per unit energy basis even more.

    11. NeverFollow says:

      “Pouch cells are higher density, that’s why everyone uses them… Look inside your cell phone.”

      I think that one advantage of cylinder versus flat is that current flow and heat transfer are more uniform, which is crucial under heavy load.

    12. Windbourne says:

      This is why Tesla hires engineers and smart ppl, rather than shysters who have no knowledge of what they speak of.

      The single biggest difference between.tesla’s AA cell approach, is ability to give lots of energy quickly, while also having GREAT thermal control. Those large pouches are cheaper to make, but then require a load of labor, and all sorts of extra work to even have the edges cooled decently, let alone the center’s.

  2. Bob says:

    It is about fast/cheap production process and coolinh.

    1. Ron M says:

      Who said the shell is a steel case I say the video for making these cells it didn’t appear that any component of the cell is steel.

      1. Pushmi-Pullyu says:

        Well, the Gigafactory flow chart shows both steel and aluminum being used to make the “can & cap”, which means the battery shell.

        1. Nix says:

          cool. Nice graphic.

      2. unlucky says:

        steel is more orange than aluminum. You can tell in the pictures and video above that the material is not aluminum but steel.

  3. Ambulator says:

    Randy Carlson has no basis except for wishful thinking for his speculative numbers. Using the numbers here I get somewhere between 300 Wh/kg and 350 Wh/kg.

    The cells are going to be vertical.

    1. ffbj says:

      I heard around 340, so you are right in the ball-park.

      1. ffbj says:

        Also top end M3 70kWh.

        1. MikeG says:

          From this article, I calculated the total battery capacity (using both 5.75 and 6 Ah values) and came up with 37-39 kWh total capacity.

          3.7 V * 6 Ah * 220 * 8 = 39 kWh

          1. ffbj says:

            So a 40kwh pack for the entry level and a 70kWh for the top end? Sounds about right.
            I heard 5750mA.

            A bit tedious but interesting.

            1. AlphaEdge says:

              That was very interesting. Thanks

          2. SimonAVEQ says:

            It doesn’t really make sense. If the 8 modules equate 40 kWh, where will the other packs go to bring it to 70 kWh for the premium trim M3?

            It would seem that the 8 modules would equate 70 kWh, and less modules would be used for the base trim M3, no?

            1. Pushmi-Pullyu says:

              At this point, nobody outside Tesla knows just how the Model 3 battery pack is configured. Any statements along that line must be speculation. The only things we can say for certain is it will use the 2170 Gigafactory cells, and that it will be configured differently than the Model S/X packs.

              Tesla is very close-mouthed about the details of its battery packs. We only know as much as we do about Model S/X packs because people have taken apart salvaged packs to see how they are put together. It’s almost certain that we won’t know much about the M3 pack until that same process occurs with the new car.

  4. Mister G says:

    Finance industry is essentially worthless to any cause unless you need to borrow money lol

  5. Seth says:

    Another benefit of multiple smaller cells over monolithic cells is reliability. Lose a single 18650 of a 96s74p pack as Tesla uses and you loose about 5% of available energy. But your car will still work.

    My MiEV failed a single 50Ah cell and halted the vehicle. The drawback of a 88s1p pack. For the Leaf it’s 96S3P iirc, so better, but not great.

    So with a 2170 it would still be a 96s50p pack (if they are going with 96 in series as seems to be the most common now). But still generally quite reliable.

  6. SparkEV says:

    I would love to have these cells for my power tools!

  7. Arthur says:

    Yes, Boeing used very big cells in their 787. And got a hell of problems.

  8. DangerHV says:

    I’m estimating around 5 Ah per 2170 cell. has anyone seen the above estimate before “…and the 2170 has been tested at 5,750-6,000 mA”?

    1. ffbj says:

      That’s what is claimed. Sounds about right on the low end.

    2. Jake Brake says:

      Im thinking 5500 tops, 4800mah minimum.

  9. agzand says:

    I think the cells will continue to be vertical. The headroom issue with rear seat indicates a thick floor.

    1. agzand says:

      Also a thick pack provides more rigidity, which is desirable both for the chassis and safety.

      1. Robert K says:

        You could only use the battery casing, and yes thicker pack increases stiffness, but because of the roof structure there is so to say already a high second moment of area.

        Furthermore is the idea behind the casing that it should protect the cells in case of an accident. If you apply an additional load case by including it to your chassis, the cells won’t be protected sufficiently.

        But generally speaking it is a problem with the thick floors. On the one hand the seating position in future evs will be higher due to the thick floor (which complies with the current SUV trend) on the other hand car companies reduce drag by reducing the car’s frontal area, which is especially important for ev range. This leads to a reduced interior height.

        Sitting in the back of Model S/X ist already not a real pleasure. The leg angle is not really convenient and head room is also scarcely dimensioned. I was especially disappointed by sitting in the back of the model x.

  10. Priusmaniac says:

    On the long term it may be further optimized on cooling by having a hole in the center of the cylindrical cell. A kind of donuts cell but which would have the same height as a cylindrical cell. Thanks to the coolant through the center, the outer diameter could be increased somewhat further.

  11. arne-nl says:

    “but it can deliver almost double the current (the 18650 delivers 3,000 mA, and the 2170 has been tested at 5,750-6,000 mA).”

    I never know how to judge these EV sites that don’t know their stuff. It’s 3000 resp. 5750-6000 mAh of energy these cells can store. They can deliver a multiple of that in current (> 5C)

    1. Djoni says:

      So, you’re describe available power from an energy content.
      The energy content or capcity stay the same.
      Power is an other matter.
      What’s new here?

      1. arne-nl says:

        What’s wrong here (not new, it happens all the time) is that they want to describe the energy content and use power ratings instead. The max current a cell can deliver determines how much power you can draw from it, not how much energy it stores.

        Power and energy are different things.

    2. Pushmi-Pullyu says:

      Engineers seldom write newspaper articles.

      But it certainly would be nice if writers had their articles proofread by someone technically qualified before publication. Sadly, journalism is rarely up to that standard. For most publications, getting the article by 5 PM is more important than getting it right.

      Major print news magazines are, in my experience, the best source for accurate facts. They usually have more time to fact-check their articles before they go to press, since they’re on a monthly schedule rather than a daily one.

      1. arne-nl says:

        How would you rate a site where the editors don’t know the difference between power and torque? Or acceleration and top speed? Or displacement and rpm?

        When you want to write about a subject, you should know the basics. And if you’re not an engineer, you should LEARN the basics.

        The difference between power and energy, kW and kWh, mA and mAh is some of that basics that you HAVE to grasp before even thinking about writing for an EV site.

  12. Alfred says:

    @EVANNEX: The volume of a cylinder is 𝝅 r2 h, therefore the increase of volume of the 21700 compared to the 18650 is 33%, not 50%. (21.98 cc and 16.53 cc).

    1. Ambulator says:

      It would be 36% if you ignore the length increase. With the additional length it’s 46.5% more volume.

      1. Alfred says:

        Thanx! I’ve made a mistake, using 20 instead of 21 for the 21700… shame on me!

  13. speculawyer says:

    I’ve long been skeptical about Tesla’s usage of cylindrical cells as opposed to pouches & prismatic cells.

    But, like many areas, it seems that I was wrong and Tesla was right. Cylinders provide a nice strong structure that minimizes the packaging material. The spiral insides is an efficient way of creating a lot of anode/cathode contact area.

    Cylinders always seemed a bit clunky due to the gaps between adjacent packed cylinders thus reducing volumetric density. But all battery packs require some gaps for coolant flow thus the gaps provide a feature instead of just being reduced density.

    And the mass production equipment for cylindrical cells seems quite mature and efficient. Long sheets of anode, separator, and cathode are just wound up as a roll to create a cell.

    Tesla does make some mistakes. But they seem to make fewer mistakes than I often blame them for.

    1. Nix says:

      That’s what she said?


    2. bogdan says:

      I think the cylindrical cell packs are more expensive and complex opposed to pouches & prismatic cells. But that’s the price you pay for quality.
      If a small cell fails, the big pack will not really notice.
      The lost space is used for cooling.
      Model S have proven that the aging of the battery isn’t an issue.
      More freedom in the pack design.

      I think Tesla doesn’t have the philosophy of OEM yet:
      – buy the cheapest
      – sell with big profit margin
      – let it fail so u can sell the spare parts with huge margins

      Tesla is still trying to be No#1 in consumer satisfaction. The OEMs don’t give a **** about that.

  14. cab says:

    I can see how all of this could allow Tesla to launch the Model 3 with the requisite 200ish miles of range and simultaneously announce the Model S will now have 400ish. They will need this (and more) to try and justify the higher price point and likely much greater profit percentage of the Model S.

    That’s the kicker with the Model 3 – it has the potential to steal a LOT more sales from the Model S than the average BMW 7 series steals from a BMW 3 series. The “thing” that made the Model S so notable (nice looking, long range powerful electric) will be available a lot cheaper in the Model 3 and Tesla needs to do something to differentiate its profit leader from the Model 3…and they need to do it simultaneously with the Model 3 launch.

    1. arne-nl says:

      Think about it. Is BMW cannibalizing sales of the 7-series with the 5 or 3 series? Or do they put just enough luxury and size and performance into the 7 series to convince buyers?

      The higher price is for many people a pro, because they can then drive something they feel is exclusive and communicates their (financial) success to the world.

      Logic plays only a minor role in choosing a car.

  15. Pushmi-Pullyu says:

    The article says:

    “It’s also assumed (though Tesla won’t confirm any numbers at this point) that the battery chemistry has been improved, yielding a higher energy density.”

    That’s not just an assumption, that has been stated as fact by both Elon Musk and JB Straubel.

    Quoting a transcript of a July 2014 Tesla conference call:

    25:23 Journalist: On the Gigafactory, is the chemistry going to be the same battery chemistry that you’re currently using or is that part of the discussions that are going on with Panasonic?

    25:34 Elon Musk: There are improvements to the chemistry, as well as improvements to the geometry of the cell. So we would expect to see an energy density improvement and of course a significant cost improvement. JB, do you want to add anything?

    25:53 JB Straubel: Yeah, that’s right. The cathode and anode materials themselves are next generation. We’re seeing improvements in the maybe 10% to 15% range on the chemistry itself.

    26:09 Elon Musk:Yeah, in terms of energy density.

    26:09 JB Straubel: Energy density. And then we’re also customizing the cell shape and size to further improve the cost efficiency of the cell and our packaging efficiency.


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