ElectricMotorcycleForum.com
General Category => General Discussion => Topic started by: Richard230 on October 06, 2020, 03:41:21 AM
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Here is an article that was in my newspaper yesterday that describes Tesla's new larger battery cell, which I thought most people here would find interesting if they already didn't know about it.
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That last bit about "too many electric vehicles concentrate on high end performance" strikes a chord with me. I like my Zero S because it is practical. It's fast enough to go on the highway, and thanks to the charge tank I can get back on the road after a leisurely meal. That's all I really need... I don't need all the power of the SR or the SR/F. I hope Zero continues to make relatively inexpensive and practical electric motorcycles for those of us who outgrew the need to be the fastest kid on the block.
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That last bit about "too many electric vehicles concentrate on high end performance" strikes a chord with me. I like my Zero S because it is practical. It's fast enough to go on the highway, and thanks to the charge tank I can get back on the road after a leisurely meal. That's all I really need... I don't need all the power of the SR or the SR/F. I hope Zero continues to make relatively inexpensive and practical electric motorcycles for those of us who outgrew the need to be the fastest kid on the block.
I feel the same way. My Zero S is plenty fast enough for me. ;)
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One of the things I like about ev's is that (other than initial cost perhaps), there 's no real penalty during normal day - to-day use. No change in efficiency, drivability, etc.
Sent from my SM-T380 using Tapatalk
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S represent! ^-^
Yeah, I love my bike and wouldn't have as much fun on any other. If I could have 2C charging while I was out, tho...
-Crissa
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Agreed about bike power outputs here... but the same problem is afflicting the motorcycle industry as a whole, with spiralling power outputs at odds with actual customer needs. I hope Zero doesn't go down the "more power" route and spends the R&D money on range, quality, and farkles instead.
Cas :)
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Agreed about bike power outputs here... but the same problem is afflicting the motorcycle industry as a whole, with spiralling power outputs at odds with actual customer needs. I hope Zero doesn't go down the "more power" route and spends the R&D money on range, quality, and farkles instead.
Cas :)
For several years now I've been wondering why motorcycle manufacturers are making bikes with motors SO powerful you need all kinds of electronic "policemen" to prevent the rider from killing themselves. I can understand why road racers would want this, but I see no reason why a street rider on public roads would want them. When the BMW S1000RR first came out, a friend did a track day with his. Out of curiosity, he turned off all of the rider aids for a session and found out he could barely keep the bike on the track and nearly crashed several times. This from a guy whose ridden powerful liter bikes longer than I'd known him.
Sadly, the real reason the manufacturers pursue this is because it's what customers WANT. The SR outsells the S even though it costs thousands more to purchase and hundreds more per year to insure BECAUSE it is more powerful, not because of any practical real world reason. Zero has doubled down on this by not selling the larger battery in the S to give the SR one (artificial) advantage; that of increased range. Make the same battery available in the S (in the US; Europe can still get the larger battery in the S and DS) and there is no practical advantage to the SR.
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Getting back on track: I seem to remember Zero went with Farasis because, unlike Tesla, they uses flattened, sheet-like cells and not the cylindrical ones used by Tesla. This allows them to pack more cells more tightly together than the cylinders which would leave a lot of empty space within the battery. In a car, battery size isn't all that important; I understand the entire chassis of a Tesla is a battery pack. Motorcycle designers don't have that kind of freedom.
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Getting back on track: I seem to remember Zero went with Farasis because, unlike Tesla, they uses flattened, sheet-like cells and not the cylindrical ones used by Tesla. This allows them to pack more cells more tightly together than the cylinders which would leave a lot of empty space within the battery. In a car, battery size isn't all that important; I understand the entire chassis of a Tesla is a battery pack. Motorcycle designers don't have that kind of freedom.
That is my understanding also. But flat cells do make it more difficult to cool the battery pack. Using cylindrical cells no doubt are easier to cool when they are all packed together, especially when they are liquid cooled as they are in almost all cars. As usual, there are always trade-offs with every design decision. ;)
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Flat cells produce less heat than tabbed cylindrical cells, and you can put the cooling at the edges instead of the sides. (Which is the two reasons the tabless design is such an improvement)
Tesla chose cylinders because they were cheap.
-Crissa
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Tesla also point out that the sides of the batteries do not get hot: it's the top and bottom that heat up.
If you look at the spaces between the packed cylindrical cells you can also see that there's not too wasted space (just under 10% in fact), and doubtless the gaps can be used for additional structure or cooling channels anyway so ... I suspect it's good.
Cas :)
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Here is a lot more information regarding Tesla's new battery design: https://www.youtube.com/watch?v=Y0xseoeriPE&feature=youtu.be
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That last bit about "too many electric vehicles concentrate on high end performance" strikes a chord with me. I like my Zero S because it is practical. It's fast enough to go on the highway, and thanks to the charge tank I can get back on the road after a leisurely meal. That's all I really need... I don't need all the power of the SR or the SR/F. I hope Zero continues to make relatively inexpensive and practical electric motorcycles for those of us who outgrew the need to be the fastest kid on the block.
I have said this hundreds of times. Almost all vehicles today are too powerful. Except for some sections of the German Autobahn every road in the 1st world has speed limits, usually aggressively enforced. Almost every vehicle sold in these markets can go much faster than the speed limit. Why? To get to work 1 minute earlier? Less power means lighter vehicle, means longer range for same amount of energy.
Edit.
PS. These are not Tesla batteries. There are no Tesla batteries. Tesla is not a battery manufacturer. Panasonic supplies nearly all cells Tesla uses, making them Tesla branded Panasonic batteries. :o
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PS. These are not Tesla batteries. There are no Tesla batteries. Tesla is not a battery manufacturer. Panasonic supplies nearly all cells Tesla uses, making them Tesla branded Panasonic batteries. :o
That has changed. They are making battery cells at the new facility in Fremont where the battery presentation was held. It is expected to produce 10 GWh/year when up to speed, which will make it (briefly) one of the largest battery cell factories in the world by output.
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Alas. While Tesla is believed to be building their own battery factory I believe the "new facility in Fremont" is not up and running yet.
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The test factory in Fremont is running, yes.
But they plan to build full-size ones at their other facilities once they have the kinks knocked out.
Basically, Fremont is where they put pilot programs, learn how to lay things out, while the other facilities is where they multiply it. Fremont is closest to a port and other tech facilities, so while some may be optimized for other things, Silicon Valley is optimized for development. All the things are there.
They also said they were already testing cars with the batteries in them.
-Crissa
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So it's a test factory (still). :)
I do find it funny how people treat batteries from trashed Tesla cars as some sort of treasures. Not realizing they are actually nothing more than used Panasonic (and in some cases, in the newest cars, LG or CATL) cells.
According to this https://www.theverge.com/2020/9/22/21449238/. "Tesla’s new cell manufacturing system is “close to working” at the pilot plant level." "The company’s 2170 cells, which are currently used in Model 3 and Model Y vehicles, are produced by Panasonic"
I do find it sad when Tesla talk about their new 4680 (46mm diameter, 80mm length) cells as huge step forward, having 5 times the energy of their old cells, 6 times the power, neglecting to mention they take much more space than the 18650 (18mm diameter, 650mm length) cells. I calculate them as taking 8 times the space. :o I'm sure someone will double check it and let me know if I'm wrong. ;D
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(46*80)/21*70=2.5 not 8.
The new cells are also more space efficient, with how they go into the car; they require less adhesive, less insulation, and are more structural. So they will be able to fit more cell mass into the same space.
-Crissa
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Thank you Crissa.
Volume of a cylinder is Pi x R2 x H. So for 4680 cell it is Pi×232×80 = 42320 x Pi = 132952 mm3, and for 18650 cell it is Pi×82×65 = 4160 x Pi = 13069 mm3. I used this website for the calculations https://www.calculator.net/volume-calculator.html?
The ratio can be done in many ways but without grabbing a calculator it is easiest if you half 132952, then you get 66476, if you half that again (1/4) you get 33238, if you half that again (1/8) you get 16619. So 1/8 of the 4680 cell is a bit bigger volume than 18650 cell.
But I did go to the website again and divided 13069 into 132952. It said said 13069 would go 10.17 times into 132952.
So it was slightly worse than I thought after the quick calculations I did in my head. Tesla gets 5-6 times the energy out of 10 times the volume. Now, this math must be wrong somewhere. Why would they start making much bigger cells if they only get half the power out of the volume? Partial answer to that could be simply fewer cells in a pack. That makes the BMS simpler and cheaper. Maybe they'd get better cooling but the bigger cell has proportionally smaller surface area, so physics would argue that the cells would need more cooling.
Another interesting theory is that they are going to switch to similar chemistry to what the A123 battery manufacturer used. It has higher cycle count than the standard Lithium Ion with Cobalt. It doesn't have Cobalt which is the most expensive part of the battery. They need more of the other materials, but the cost of extra materials will be offset by only using miniscule amounts of the most expensive material. But the A123 chemistry only has half the power density of Lithium Ion cells.
I guess the future will show us what is actually going on. Hindsight is 2020. ;D
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I don't know where you get your volume numbers.
(3.14*((46/2)^2)*80)/(3.14*((21/2)^2)*70)=5.5
The ratio doesn't change from cubic to cylinder here; I forgot the third dimension but that doesn't make it tenfold.
The actual 'cell' is a flat sheet, anyhow, so the change isn't really cubic.
-Crissa
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I see the problem. You are comparing the 4680 cell with the 21700 cell. I am comparing the 4680 cell with the 18650 cell. Now which cells was Tesla comparing?
The 4680 cell is 132952 mm3 in volume.
The 21700 cell is 24245 mm3 in volume.
The 18650 cell is 13069 mm3 in volume.
The cells are cylindrical in shape, not cubed.
PS. I used this website for volume calculations https://www.calculator.net/volume-calculator.html?
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Probably not directly volume-related by capacity... is cell power not a function of the area of the rolled up sheet of electrolytic material inside?
Anyway, nvm all that... the more pressing concern is if anyone else will ever get to use these batteries in any other vehicles.
Cas :)
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Probably not directly volume-related by capacity... is cell power not a function of the area of the rolled up sheet of electrolytic material inside?
Anyway, nvm all that... the more pressing concern is if anyone else will ever get to use these batteries in any other vehicles.
Cas :)
If you were Tesla, manufacturing your own batteries in several very expensive factories around the world because you needed every battery you could make to power your cars and trucks, would you sell your batteries to any other competitor, or to a motorcycle or some other power-sports company? I don't think I would. ;)
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Well, absolutely not :)
Cas :)
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An EV news video said LG Chem teased it will be announcing a very similar cell in the very near future.
I found it interesting because Damon had mentioned their cells would be Korean.
This is my own theory based on a few puzzle pieces. We'll see.
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Probably not directly volume-related by capacity... is cell power not a function of the area of the rolled up sheet of electrolytic material inside?
Yes. The sheet does have a height, so volume does have an impact, but yes.
The tabless means there's no choke point at the edge of the end of the sheet, which frees the cylinder from it's size constraint. So the whole sheets gets to be used.
And I'm not sure why I wouldn't compare the cells Tesla is using now vs the cells they will be using.
-Crissa
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I see the problem. You are comparing the 4680 cell with the 21700 cell. I am comparing the 4680 cell with the 18650 cell. Now which cells was Tesla comparing?
The 4680 cell is 132952 mm3 in volume.
The 21700 cell is 24245 mm3 in volume.
The 18650 cell is 13069 mm3 in volume.
The cells are cylindrical in shape, not cubed.
PS. I used this website for volume calculations https://www.calculator.net/volume-calculator.html?
But you got it wrong. In your first message you use 8 as the radius of an 18650. Half of 18 is 9, not 8.
9 x 9 x 65 x PI = ~16540 mm3
I think the other two calculations are correct.
The primary purpose of the larger cells is to drive down manufacturing costs. Fewer cells means fewer parts, fewer manufacturing and assembly operations, and fewer potential failure points.
The new form factor also may make the use of the cells as structural components more tenable. The aspect ratio between cell diameter and height is more favorable from a structural perspective. Is the wall thickness the same? I don’t know.
Despite all the online speculation otherwise, when Tesla introduced the 2170 format Elon said the primary driver was cost. It’s likely the same for the 4680.
The tabless design makes the larger cell practical, solving cooling and charge/discharge rate issues with a traditional single tab in such a large cell. It might also benefit the smaller form factors.
Regardless of the cells, it’s the pack as a whole that matters. Certainly eliminating the cooling ribbon used by the 18650 and 2170 packs will improve the horizontal density of the Tesla battery pack.
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Thank you Alan.
Good points. It's amazing how much 1 mm changes. :)
132952/24545=5,5. Volume of 21700 cell goes 5,5 times into 4860 cell. Since Tesla claims 5-6 times better cell that sounds about right. But it's more or less the same energy for the same volume. There is probably small weight savings, just in the casing materials.
I doubt the cells will become structural, that would require relatively larger wall thickness, adding weight to the cells, and taking up precious space that could be used to store energy. If you are taking the same amount of energy out of the same volume it should heat up the same. With the bigger cell having less surface area for cooling it would heat up more, especially in the core.
While there are fewer potential failure points, each failure is likely to have more effect. Cell that goes into thermal runaway is burning with 5,5 times the energy release. Harder to put out, and 5,5 times the material lost. But that sort of failures probably does not happen much in modern cell factory.
132952/16540=8. Volume of 18650 goes 8 times into 4860. 18650 is, as far as I know, still used in the older Tesla car designs. Tesla X for example.
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Having less wasted space will make the cells more structural, especially as they're compressed. Right now they use big I-beams and the cells will instead be packed tightly with cooling rails atop or below them. All that means they can mount them in something that itself is rigid instead of gooey or soft like the material they use now.
Basically, no ribbons, plus rigid mounting medium, means no I-beams, which means even more space saved.
And Tesla is looking at sheathing them in even less material! Denser means more structural. The cylinders already expanded less than pouches!
-Crissa
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If you are taking the same amount of energy out of the same volume it should heat up the same. With the bigger cell having less surface area for cooling it would heat up more, especially in the core.
Not necessarily since the tabless design of the new cells will have lower internal resistance. This is how they're claiming much faster charging speeds.
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Having less wasted space will make the cells more structural, especially as they're compressed. Right now they use big I-beams and the cells will instead be packed tightly with cooling rails atop or below them. All that means they can mount them in something that itself is rigid instead of gooey or soft like the material they use now.
Basically, no ribbons, plus rigid mounting medium, means no I-beams, which means even more space saved.
And Tesla is looking at sheathing them in even less material! Denser means more structural. The cylinders already expanded less than pouches!
-Crissa
How are they cells compressed? So the cells will be "packed tightly with cooling rails atop or below". Mounted in "something that itself is rigid". That sounds like regular standard batterypacks, i.e. loose cells in structural container. The cooling rails will simply take up space atop or below the cells, instead of between them, unless the cooling rails will be structural part of the cell container. I guess we'll see what the Tesla geniuses have designed when it actually reaches the market.
Cylinders expand less than pouches because the expansion is inside the cylinders. The cylinders have to be slightly bigger, little bit of wasted space, to allow for the expansion of the materials inside.
I still call phooey on the claims of 5-6 times improvement, simply because they're not comparing same size cells. I'd say the cell changes are at most 10% improvement (probably closer to 5%) for same volume. And they could have continued using the 18650 or 21700 cells with the cooling rails moved "atop or below" the cells "packed tightly" and get similar improvements. And they could have made the no ribbon improvement to the 18650 or 21700 cells. I think Alans suggestion of them simply using fewer cells to drive down costs is the main reason for the new cells. Battery technology these days is big investment for small gains.
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And they could have made the no ribbon improvement to the 18650 or 21700 cells.
I think the removal of the cooling ribbon is made possible by the tabless design. In addition to reducing resistance it conducts heat from the interior of the cell to the end caps, so cooling via top and bottom plates becomes effective. As I said earlier it seems like the tabless design could be applied to other (cylindrical) cell formats such as 18650 and 2170 to give the same benefits as it does to the 4680 format.
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How are they cells compressed?
In between the cooling rails?
So the cells will be "packed tightly with cooling rails atop or below". Mounted in "something that itself is rigid". That sounds like regular standard batterypacks, i.e. loose cells in structural container.
Yes and no. Tesla is trying to get approval for a safety medium which is also rigid. So right now the box itself is the structure, but they want something which is laminated together where the cylinders are part of the structure instead of contained in it. I don't know if that means they're countervailing forces or just glued in place; but their anti-fire resin itself is supposed to be rigid structure. Which is wholly unlike how Zero or Energica cells are potted.
I still call phooey on the claims of 5-6 times improvement, simply because they're not comparing same size cells.
Per cell, which is how fast they come out of the factory, their numbers hold. But yes, that's nearly all from just 'being bigger'. But no one could make bigger cylindrical cells and have them perform as well until now.
Bigger cells means they can make more battery capacity in the same per-unit time. Bigger cells means they can try their 'structural medium'. Dry cells means smaller factory, so they can fit more production lines in the same place. Bigger, in their case, is better. And the tabless allows that to happen.
-Crissa
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My English comprehension seems to be failing me. :(
But to the part I understood.
But no one could make bigger cylindrical cells and have them perform as well until now.
Bigger cells have been made, maybe not cylindrical, but there are huge Lithium based cells available. Once they get up to this size the fact that they're cylindrical starts to hold them back. IMHO, they'd make bigger steps by switching to pouch cells. Don't forget that the original 18650 were only used because they were readily available for "low prices" in high quantities.
There are many performance parameters, which one you think is most important is up to you.
Energy density, Operating temperature, Safety, Durability, Charging time, Output power, Elimination of cobalt. These cells
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The cells used in my 2008 Electric Motorsport GPR-S were made by Hi Power (not exactly the right name for that company ::) ) and were about the size and shape of a home Webster Dictionary. Their claim to fame were that they couldn't handle power draws of over about 50 amps very well and when used to power an electric motorcycle sometime tended to expand like a balloon and vent gas at inopportune moments. :o I suspect they were designed more for storing electricity to power decorative lights on Asian buses than they were for EV motivation. ::)
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There's also how fast the cells can be manufactured, how cheap it is to manufacture, how much resources it takes, etc.
That's why Tesla went with cylindrical cells: They are cheap and fast to manufacture. But manufacturing machines can only run so fast, so at that point, to speed up you need more factory or bigger cells to have more capacity.
Bigger cells were not reliable in cylinders because of the tabs. Hense the new design.
-Crissa
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Congratulations on 2000 posts Crissa.
Here is a nice youtube video at the EEV blog about the 4680 cell. A guy who actually knows a little bit about electronics and is mildly impressed.
https://www.youtube.com/watch?v=hbPKE62aM0U
Edit. Real explanations instead of marketing lies speech. If I'd found this video in the beginning I would have linked to it. It would have saved me few posts. ;D
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That certainly was an interesting video, Zarathustra. Thanks for posting it. My feeling has always been the the real advantage for Tesla by using the cylindrical cells is the ease of quickly manufacturing millions of them using robotic machines, compared with manufacturing pouch cells. Any other advantages are just gravy. ;) When you are planning to sell millions of electric vehicles a year, money becomes a big deal, especially when government subsidies are shrinking and in their case, disappearing.
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Here is a nice youtube video at the EEV blog about the 4680 cell. A guy who actually knows a little bit about electronics and is mildly impressed.
If the ideas behind the 4680 cell format are so obvious why has it taken a number of decades for anyone to implement them? Many innovations are obvious after the fact, physics is just physics. Brilliance is in seeing how to take best advantage of physics, and in the case of commercial products, costs also. The largest barrier to EV adoption is cost.
This guy is not considering the financial and manufacturing aspects of the 4680, which is the primary reason for the design. 5x energy implies 1/5 as many cells are required to make a battery pack of a given capacity, a great reduction in manufacturing and quality control operations and parts counts and thus, costs. There are also possible benefits in reliability. 6x power is significant because a battery pack of a given capacity will be capable of 20% more power, which also has implications for potential charge rates and charging times. The 16% range increase is a result of weight savings for a battery pack of a given capacity, so smaller battery pack can be used to achieve the same range goal, again reducing vehicle cost.
The primary commercial and practical significance of a battery cell design is the battery pack design it enables.
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The Tesla Battery Day presentation is focused is on how to scale up battery production and decrease battery costs, not on the 4680 cell design or EV range.
https://tesla-share.thron.com/content/?id=96ea71cf-8fda-4648-a62c-753af436c3b6&pkey=S1dbei4 (https://tesla-share.thron.com/content/?id=96ea71cf-8fda-4648-a62c-753af436c3b6&pkey=S1dbei4)
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If the ideas behind the 4680 cell format are so obvious why has it taken a number of decades for anyone to implement them?
Well...
The spending to many the continuous or tabless cell just didn't make economic sense to small cells, which is where the vast majority of cylindrical cells are used. It wasn't just the tabless idea, you also need more precise cell manufacture. Usually saving money in manufacture is about adapting to a less precise but cheaper method.
For larger cells, it made sense to just make larger cells instead of slowly ramping up. Remember, pretty much only Tesla decided to use cylindrical cells as a good atomic unit for larger batteries. This is because just building a large battery was sort-of cheaper than making many small ones. But small ones can be made fast and cheap... But have you seen how complex Tesla battery packs were?
Obvious doesn't mean 'there is money to do it' because often the inobvious part is 'how much will this save me vs the investment to make it so?'
-Crissa
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This guy is not considering the financial and manufacturing aspects of the 4680, which is the primary reason for the design. 5x energy implies 1/5 as many cells are required to make a battery pack of a given capacity, a great reduction in manufacturing and quality control operations and parts counts and thus, costs. There are also possible benefits in reliability. 6x power is significant because a battery pack of a given capacity will be capable of 20% more power, which also has implications for potential charge rates and charging times. The 16% range increase is a result of weight savings for a battery pack of a given capacity, so smaller battery pack can be used to achieve the same range goal, again reducing vehicle cost.
Please don't fall into the trap of thinking that manufacturing costs will be the same for both cells. The 4680 cell will requires 5-6 times the raw materials of 21700 cell. Mining costs for materials that much higher for each 4680 cell. There will be some savings in machines required to make the cells but will that be a game changer? I still don't see what would be that cost reduction game changer.
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Please don't fall into the trap of thinking that manufacturing costs will be the same for both cells. The 4680 cell will requires 5-6 times the raw materials of 21700 cell. Mining costs for materials that much higher for each 4680 cell. There will be some savings in machines required to make the cells but will that be a game changer? I still don't see what would be that cost reduction game changer.
The cost savings is in decrease in the reduction in the number of cells to make a battery pack of a given capacity. One-fifth as many parts and manufacturing operations saves money. Tesla moved to 2170 for the Model 3/Y to save money, per Elon Musk. It’s battery pack cost that matters in the end, not cell cost.
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Most of the per-cell cost is manufacturing it. More cells, more cost. That's why GM went with large prismatic cells, to lower the per-cell cost.
-Crissa
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The new visualization from Tesla shows how they’ll be packing the cells closer together and eliminating the cooling ribbon of current battery packs. Probably the cell bottoms will be fully glued to the cooling plate and the interstices between cells also filled with glue to make a very solid honeycomb-like structural component. Sandy Munro thinks they’ll use manifolds welded to the positive and negative contacts at the top of the cells.
https://insideevs.com/news/456644/tesla-shows-4860-cells-and-pack/ (https://insideevs.com/news/456644/tesla-shows-4860-cells-and-pack/)