Tesla's Model 3 2170 cells=same energy desity as 18650's

[AnxietyRanger]

@stopcrazypp Why would we assume Tesla putting round objects next to each other in a rectangular manner?

 

[stopcrazypp]

@stopcrazypp Why would we assume Tesla putting round objects next to each other in a rectangular manner?

Not rectangular manner, but triangular manner (that's the packing method I used).

The Model S uses a similar pattern, although there are coolant lines in between. It's an efficient patterned method to pack circles into a rectangle (which is largely the challenge of packing cylindrical cells into a rectangular module).

Edit: Model 3 modules seems similar in the packing method:

There are other more specific algorithms that involves tweaking a couple of cells into an unusual position (such that you won't have straight rows across), but it increases the difficulty of manufacturing.

It's just an academic exercise to see if a smaller diameter cylinder is easier to pack than a larger one.

 

[AnxietyRanger]

It's just an academic exercise to see if a smaller diameter cylinder is easier to pack than a larger one.

While I appreciate the exercise, I fear it is misleading as far as my theory goes at least. I am assuming one point Tesla optimized with this cell-size was their packaging.

I see others may believe 2170s are only about cost and may actually come with deterimental or neutral packaging effect. My theory is, I admit, against that thinking.

So, yes, my working theory is that even with chemistry being equal, a Model S/X sized pack of 2170s can contain more kWh than a pack of 18650s (assuming potentially a modest pack height increase).

It will be easy to see if this theory is wrong, eventually.

 

[stopcrazypp]

While I appreciate the exercise, I fear it is misleading as far as my theory goes at least. I am assuming one point Tesla optimized with this cell-size was their packaging.

I see others may believe 2170s are only about cost and may actually come with deterimental or neutral packaging effect. My theory is, I admit, against that thinking.

So, yes, my working theory is that even with chemistry being equal, a Model S/X sized pack of 2170s can contain more kWh than a pack of 18650s (assuming potentially a modest pack height increase).

It will be easy to see if this theory is wrong, eventually.

The thing is I don't think they will use the same chemistry for both types of cells, so perhaps we will never really find out about this theory. The pack height is also a mystery too in terms of how to count it (would that be counted as "free" or factored in into the density calculation).

 

[AnxietyRanger]

The thing is I don't think they will use the same chemistry for both types of cells, so perhaps we will never really find out about this theory. The pack height is also a mystery too in terms of how to count it (would that be counted as "free" or factored in into the density calculation).

Well, surely the height is a part of my theory, so my theory by no means is only that the cell diagmeter is more optimal. It is the whole thing that reeks to me they have optimized this.

I don't know if there is anything to the 130 kWh rumor exactly. I am just surprised people seem so reluctant to entertain Model S/X packs beyond 100 kWh in this thread. I think that is potentially quite misleading thinking.

I mean, Tesla is strangely silent on what Model 3 achieved with the 2170s and there is the rumor of the 85 kWh Model S/X pack replacing the 75 kWh... What if there is a positive surprise in how much kWh they managed to fit into the Model 3 too? Maybe not, just thinking.

We shall see eventually of course. If Model S/X are still stuck at 100 kWh when the 2170s come, then I was wrong obviously.

 

[stopcrazypp]

Well, surely the height is a part of my theory, so my theory by no means is only that the cell diagmeter is more optimal. It is the whole thing that reeks to me they have optimized this.

I don't know if there is anything to the 130 kWh rumor exactly. I am just surprised people seem so reluctant to entertain Model S/X packs beyond 100 kWh in this thread. I think that is potentially quite misleading thinking.

I mean, Tesla is strangely silent on what Model 3 achieved with the 2170s and there is the rumor of the 85 kWh Model S/X pack replacing the 75 kWh... What if there is a positive surprise in how much kWh they managed to fit into the Model 3 too? Maybe not, just thinking.

We shall see eventually of course. If Model S/X are still stuck at 100 kWh when the 2170s come, then I was wrong obviously.

I think that will depend on how far forward that point is (S/X still using same pack footprint or different, what about chemistry improvements?) and also Tesla's strategy at that point more than the technicality of whether a 18650 size cell is more efficient to pack than a 2170.

For example, if Tesla decided 100kWh was the "good enough" point, then even if they could have added more capacity, they rather just use it to reduce the size/weight/cost of the pack.

However, if they decided they want to continually push higher, then regardless of 18650 or 2170 they will probably figure a way to push it higher (whether through chemistry change or packing more cells like they did for 100kWh).

 

[calisnow]

I am just surprised people seem so reluctant to entertain Model S/X packs beyond 100 kWh in this thread.

me too

 

[AnxietyRanger]

I think that will depend on how far forward that point is (S/X still using same pack footprint or different, what about chemistry improvements?) and also Tesla's strategy at that point more than the technicality of whether a 18650 size cell is more efficient to pack than a 2170.

For example, if Tesla decided 100kWh was the "good enough" point, then even if they could have added more capacity, they rather just use it to reduce the size/weight/cost of the pack.

However, if they decided they want to continually push higher, then regardless of 18650 or 2170 they will probably figure a way to push it higher (whether through chemistry change or packing more cells like they did for 100kWh).

Are you seriously expecting Tesla to continue innovating around the 18650?

What am I missing here. For me it is so obvious 2170 is the future of Tesla and that we are likely to see significant pack, range and performance improvements through it. Model S/X included.

Don't believe Tesla's anti-sell or Elon's "we'll stop at 100"...

 

[calisnow]

Well, surely the height is a part of my theory, so my theory by no means is only that the cell diagmeter is more optimal. It is the whole thing that reeks to me they have optimized this.

I don't know if there is anything to the 130 kWh rumor exactly. I am just surprised people seem so reluctant to entertain Model S/X packs beyond 100 kWh in this thread. I think that is potentially quite misleading thinking.

I mean, Tesla is strangely silent on what Model 3 achieved with the 2170s and there is the rumor of the 85 kWh Model S/X pack replacing the 75 kWh... What if there is a positive surprise in how much kWh they managed to fit into the Model 3 too? Maybe not, just thinking.

We shall see eventually of course. If Model S/X are still stuck at 100 kWh when the 2170s come, then I was wrong obviously.

I don't think you're wrong. If we don't get 130 kwhr then maybe 105/110/115/120. But I'd think that *something* is more likely than nothing during the next 12 months.

 

[AnxietyRanger]

I don't think you're wrong. If we don't get 130 kwhr then maybe 105/110/115/120. But I'd think that *something* is more likely than nothing during the next 12 months.

Thanks @calisnow. I was thinking I must be a going crazy, because to me it seems so obvious this is a possibility - even likelihood. The pushback just seemed so odd.

 

[AnxietyRanger]

Are you seriously expecting Tesla to continue innovating around the 18650?

What am I missing here. For me it is so obvious 2170 is the future of Tesla and that we are likely to see significant pack, range and performance improvements through it. Model S/X included.

Don't believe Tesla's anti-sell or Elon's "we'll stop at 100"...

And @transpondster actually Disagreed with that message.

What am I missing here?

 

[R.S]

I don't think you're wrong. If we don't get 130 kwhr then maybe 105/110/115/120. But I'd think that *something* is more likely than nothing during the next 12 months.

I do agree, there will be another increase, but I also do think it won't involve putting in even more battery mass, by using the extra 5mm. I do think the next increase in range will only come through energy density improvements and might not necessarily involve the 2170s, or at least not to get to more kWh.

Thanks @calisnow. I was thinking I must be a going crazy, because to me it seems so obvious this is a possibility - even likelihood. The pushback just seemed so odd.

I don't think there is a pushback against the idea of Tesla getting more kWh into the cars, but rather that it will be 130 kWh, or your assumptions in general. If someone says a bigger cylinder is easier to package than a smaller cylinder, I just have to disagree. I'd do the same if you would have said 5 is bigger than 7.

So while I do agree that there will be a Model S with over 100 kWh, maybe even 130 kWh some day, I don't think there will be a S130D any time soon.

 

[AnxietyRanger]

Well @R.S, fair enough, at least one disagreement is nicely articulated there. I appreciate it.

As for numbers, I am using the 130 kWh rumor just as a sort of reminder what the chatter has been, I don't mean to be fixated on that.

Basically my logic is: the Model S/X battery, as is, is pretty much "full" on 18650's at 100 kWh. Even Elon Musk said they'd stop there, which I didn't take literally but more as an acknowledgement they'd come to the end of the line with the current setup. So IMO it makes sense the next step involved the new cells.

Now, how much of that additional capacity comes from larger physical cells (say, higher) or new chemistry, that is an open question. I am not discounting the possiblity of new chemistry, just noting that so far most of the talk seems to be that energy density on the chemistry level is not (yet) changing...

Something I struggle with most is when people don't seem to believe the next step will be 2170 batteries. Why is that? Elon Musk has called the 18650 an accident of history and not optimal. Sure, they'll run it for the transition duration, maybe still many months, but why wouldn't they move to the 2170 on Model S/X as well? Why make some interim pack with 18650's?

I'm not saying the latter is impossible, but it seems very unlikely to me. I find it surprising so few people are talking about 2170s coming to Model S/X. To me it seems obvious they are coming and probably sooner rather than later.

 

[R.S]

Well @R.S, fair enough, at least one disagreement is nicely articulated there. I appreciate it.

As for numbers, I am using the 130 kWh rumor just as a sort of reminder what the chatter has been, I don't mean to be fixated on that.

Basically my logic is: the Model S/X battery, as is, is pretty much "full" on 18650's at 100 kWh. Even Elon Musk said they'd stop there, which I didn't take literally but more as an acknowledgement they'd come to the end of the line with the current setup. So IMO it makes sense the next step involved the new cells.

Now, how much of that additional capacity comes from larger physical cells (say, higher) or new chemistry, that is an open question. I am not discounting the possiblity of new chemistry, just noting that so far most of the talk seems to be that energy density on the chemistry level is not (yet) changing...

Something I struggle with most is when people don't seem to believe the next step will be 2170 batteries. Why is that? Elon Musk has called the 18650 an accident of history and not optimal. Sure, they'll run it for the transition duration, maybe still many months, but why wouldn't they move to the 2170 on Model S/X as well? Why make some interim pack with 18650's?

I'm not saying the latter is impossible, but it seems very unlikely to me. I find it surprising so few people are talking about 2170s coming to Model S/X. To me it seems obvious they are coming and probably sooner rather than later.

Yea, they would definitely use new cells, the question is if they are 2170s, or 18650s. I personally don't think adding more mass is the right solution, so I do think any improvement will come through energy density improvements. Making the pack heavier and heavier can't really be a long term solution.

In theory going for the larger cells would be a good idea, but there are two problems, that might give a reason for keeping the 18650s

1) We don't know how much the bigger form factor has an influence on discharging, charging and general cooling. So it might make sense to keep the 18650s, if a 2170s pack would perform worse.

2) They actually need to fit, before Tesla can use them in the S and X. Depending on how hard the change will be, we might have to wait for a totally new generation of the S/X platform. And no, "it looks like it might fit" isn't an argument.

So only if those two aren't problems, we will see 2170s in the S/X soon. And if they change it, there will probably be at least a small improvement in range, just because it's hard to get exactly the same kWh with two different cells/formats and they will rather over-, than undershoot.

Elon's comments on not going over 100 kWh are more or less useless, because they are exactly what you'd expect no matter if something was planned, or not. I remember when they introduced the 70 kWh pack for the Roadster and Elon said there is no new one for the S planned. I think it took halve a year before they introduced the 90...

 

[Topher]

so have to just agree to disagree I guess.

No we don't. [And you don't seem at all willing to do so] I am happy to change my mind, just show me the math. I am happy to change your mind, but you have to do (or at least accept) the math. If the 2170 uses less material in the casing, show us how much that improves space utilization. If packing makes a difference let's see it (though I think the math shown so far is pretty definitive that we are talking about tenth of percents).

Vague assertions don't convince anyone.

I see others may believe 2170s are only about cost and may actually come with deterimental or neutral packaging effect.

Where did you see that? I see NO ONE making that claim. I claimed that even if you TRIED to achieve a detrimental effect, it could only be a few percent.

Thank you kindly.

 

[bmzl]

When the 2020 MS2 comes out, it will have 130kWh of 2170s for the same price as todays S100D.

 

[AnxietyRanger]

Yea, they would definitely use new cells, the question is if they are 2170s, or 18650s. I personally don't think adding more mass is the right solution, so I do think any improvement will come through energy density improvements. Making the pack heavier and heavier can't really be a long term solution.

Why do you think they would use 18650 cells with new chemistry? (Genuine question.) 2170 is what they built the Gigafactory for, right? I would expect them to retire the 18650's when possible. Maybe use them for lower-end batteries as long as needed for transition and move to 2170s for the next performance boost on the high-end... I mean, I'm not saying what you think is impossible, it just doesn't make sense to me - unless the reason is something akin to not enough 2170s being available. My timing depends on 2170 availabilty, of course...

As for the added mass, why would 2170s necessarily mean added mass? Or much added mass? I'm thinking perhaps the new cell design allows for more optimal cooling and less space used for metal inside the packs, so more could be done with the same space. The Reddit quote some messages back some along the lines of this thinking...

Now, this is speculation of course. I'm just trying to challenge some assumptions I think are in this thread... It is good to get challenged in return, so thanks @R.S for taking the time to articulate it.

Elon's comments on not going over 100 kWh are more or less useless, because they are exactly what you'd expect no matter if something was planned, or not. I remember when they introduced the 70 kWh pack for the Roadster and Elon said there is no new one for the S planned. I think it took halve a year before they introduced the 90...

Of course, but reading between the lines can still get to some nuggets. The idea of "stopping there" might well have referred to something... end of the line for 18650's could well be it IMO.

 

[R.S]

When the 2020 MS2 comes out, it will have 130kWh of 2170s for the same price as todays S100D.

And it will come with a plush unicorn mounted at each door, to keep others from damaging your doors, when opening theirs. Pretty genius actually, but it will be $8254 more expensive, which will totally suck...

 

[R.S]

Why do you think they would use 18650 cells with new chemistry? (Genuine question.) 2170 is what they built the Gigafactory for, right? I would expect them to retire the 18650's when possible. Maybe use them for lower-end batteries as long as needed for transition and move to 2170s for the next performance boost on the high-end... I mean, I'm not saying what you think is impossible, it just doesn't make sense to me - unless the reason is something akin to not enough 2170s being available. My timing depends on 2170 availabilty, of course...

As for the added mass, why would 2170s necessarily mean added mass? Or much added mass? I'm thinking perhaps the new cell design allows for more optimal cooling and less space used for metal inside the packs, so more could be done with the same space. The Reddit quote some messages back some along the lines of this thinking...

Now, this is speculation of course. I'm just trying to challenge some assumptions I think are in this thread... It is good to get challenged in return, so thanks @R.S for taking the time to articulate it.

Of course, but reading between the lines can still get to some nuggets. The idea of "stopping there" might well have referred to something... end of the line for 18650's could well be it IMO.

My main argument for the 2170s not being used is that they don't fit. If they fit, they will probably use them, if there is no disadvantage in using a larger format, like less charging/discharging performance. A larger cell should be harder to keep cool, because the surface area to volume ratio is worse.

Actually the 2170s are still Panasonic cells, just as the 18650s, so there might also be some supply contracts to be fulfilled. IDK if they will also continue to get cells from Japanese Panasonic factories, or if Panasonic will use them for something else.

Elon also said there are no plans to go for 2170s with the S and X, which of course is something I don't really trust. But because of that I don't think he meant that they won't go for more than 100 kWh with the 18650s, but just with 2170s. Why would he say something between the lines, to then just contradict the little hint with another tweet?

Elon just wants people to continue buying Teslas and Tesla stock, so he will say whatever he has to say. That's his job and I don't blame him for not announcing things in advance. A bit less optimism would be nice with other things, especially when it comes to upcoming features of the car that will come through SW, but if he says there won't ever be a more than 100 kWh Model S, or that they will sell 700k Model 3s a year, I don't mind. But I won't accept Elon quotes as proof for anything.

 

[transpondster]

And @transpondster actually Disagreed with that message.

What am I missing here?

what others said: we need chemistry breakthrough to get 30% improvements. Weight is big problem 30 kWh of extra cells are about 110kg cell level or about 140kg module with coolant level.

• Increasing cell size gives about 2% volumetric active material increase, gravimetric hopefully 3%
• height gives some improvements at pack level, only pack wall increases, but then pack "box" is about 20% total so savings will be in 1-2Į region
• any easy arrangement increases probably already implemented last year with 100 pack

What really Tesla needs to do is to create power not energy cells and let customers choose. With advent of 150kW CCS it would be logical to offer 100kWh 1,5C pack, not 105kWh 1,2C pack