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

[Topher]

- take S/X 100 as given power output (say 550kW battery power) and input (say 120kW charge rate)
- If you up the total capacity of 102.4kW (100/18650) to say 125kW (125/2170)

Nope, still makes no sense.
You give 550kW battery output, 120kw charge input. Where does the 102.4kW come from? Why would you call that a 'capacity'? When is Power ever a capacity?
What the heck does 100/18650 mean? 100 kWh (Model S) divided by a battery size (volume?)?

Care to try again?

Thank you kindly.

 

[stopcrazypp]

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"...

Elon said two relevant things.
@shashwatbakhshi Jun 19 @elonmusk when will the 2170 batteries make it to model s and model x?
@elonmusk Replying to @shashwatbakhshi No plans to change cell form factor for X and S
Elon Musk on Twitter

@elonmusk Replying to @dadxseven
No plans to change 100 kWh pack tech. You'll never worry about running out of range. Model 3 pack is about cost reduction, not performance.
6:38 PM - 20 Jun 2017
Elon Musk on Twitter

Of course that should be taken with grain of salt and certainly Tesla can change plans depending on how far forward we are looking. For example when the next gen Model S/X comes, it's likely they will consolidate to the same cell form factor. But before then there are still reasons to stick with 18650 (existing contracts with Panasonic, manufacturing capacity to satisfy volume, better heat dissipation on a per cell basis, continuing to use same module/pack architecture, etc).

 

[AnxietyRanger]

Because the 18650s FIT in the Model S and X packs (we don't know what it would take to fit 2170s). Improving the chemistry, improves the range etc. Why WOULDN'T they do it.

It is my understanding 2170s fit or can be made to fit. I can be wrong, of course. If so, moving onto 2170s and getting the scale of the Gigafactory production process would make sense. I can be wrong on that too, but just explaining my thinking.

Nope. They built the Gigafactory to produce battery cells; just that. Of whatever size, chemistry, pack configuration they need at any given time. If state of the art in batteries changes, do you expect them to demolish it, and build a new one? Neither do I.

Of course not. Obviously the Gigafactory is capable of producing whatever they set it up to produce. It is just my genuine understanding from past Tesla communicationst that they're moving attention away from 18650s to 2170s. If so, setting up 18650 production at the Gigafactory might be sort of a dead-end they'd rather avoid. This is the speculation. Obviously years down the road they will eventually replace 2170s with something new etc.

 

[AnxietyRanger]

Seeing that @Cloxxki is basically making my point again and again (as well as going on to making some interesting new ones), I am encouraged to try one more time.

@R.S @Topher

OK, let's - for the sake of argument - forget two flammable topics. They are not relevant to my thinking at all.

a) Let's forget Elon said anything, OK? It doesn't matter what he said about 100 kWh, for my argument. He has said nothing that we can rely on and let's just forget that soundbite.

b) Let's forget the 130 kWh rumor too. Let's be like it never happened, can't trust it even if it did, doesn't matter for my point in the least. I know I liked to toy with it, but it is a red-herring. Let's forget it.

OK, fair enough?

I hope that allows you see my real thinking here:

1) I believe 2170s has been found to be the optimal size for a cell, for Tesla, at this time. I believe this is more than just a cost-optimization, I believe it is an overall optimization. Whatever they learned (together with Panasonic), they put into it.

2) There may or may not be chemistry optimizations from the get-go, on the 2170. I am confident there are chemistry optimizations eventually, if not from the beginning. But be that as it may, they don't matter for my initial point.

3) I believe it is possible 2170s, even without any chemistry benefit, can fit more kWh in the same space as 18650s. Why? Because I believe Tesla has been able to lessen the amount of "scaffolding" inside the battery.

4) Given the optimization in point 1), I believe Tesla has also found 2170 to be a more optimal size for this. I.e. less wasted space compared to 18650s when considering how they can pack and heat manage them.

Basically my thinking is: Bigger cells means more chemistry and less metal structures taking space (and weight). It also IMO (I speculate) likely means a more optimal heat-management structures have been made possible (not just considering how to fit cells separately like a puzzle to a rectangle, but considering all the other elements as well how they fit optimally).

To sum it up: I think the 2170s, together with Tesla's and Panasonic's other advancements in battery making for that cell size, mean they can pack more kWh into a space than with 18650s.

Add to this the fact that the cells are higher, so assuming they fit, they will through that also pack more into the same square-footage, and that IMO Tesla is more likely to focus on chemistry improvements for the 2170s than what I assume are dead-end 18650s, I find it very likely Model S/X will get significant range and kWh (and possibly performance) upgrades from 2170s as soon as Tesla can ramp that up without harming Model S/X/3 sales...

The role of the 18650s I expect will be to maintain some Model S/X models for the time being, and while some intermediate update to those packs is possible (that "75" 85 kWh pack may be a somewhat new development?), I am expecting the next big thing to be with 2170s...

 

[AnxietyRanger]

Elon said two relevant things.
@shashwatbakhshi Jun 19 @elonmusk when will the 2170 batteries make it to model s and model x?
@elonmusk Replying to @shashwatbakhshi No plans to change cell form factor for X and S
Elon Musk on Twitter

@elonmusk Replying to @dadxseven
No plans to change 100 kWh pack tech. You'll never worry about running out of range. Model 3 pack is about cost reduction, not performance.
6:38 PM - 20 Jun 2017
Elon Musk on Twitter

Of course that should be taken with grain of salt and certainly Tesla can change plans depending on how far forward we are looking. For example when the next gen Model S/X comes, it's likely they will consolidate to the same cell form factor. But before then there are still reasons to stick with 18650 (existing contracts with Panasonic, manufacturing capacity to satisfy volume, better heat dissipation on a per cell basis, continuing to use same module/pack architecture, etc).

Yeah, so basically I don't trust that.

 

[Cloxxki]

Sorry, I think there was a misunderstanding. The density of water in your comment got me confused. I think you wanted to weigh the displaced water, to get to the volume right?

IMO just putting it in some graduated jug halve filled with water should be good enough. No need to measure the displaced water. But your idea seems fine, too.

A measuring cup versus a scale precise to 0.01gram... I know which I'd take to get cell measurements for a complex shape or lack of calipers. It's precise enough to (somewhat) grade precious metal coins.

 

[Cloxxki]

Even if the new cells were 1870's, they'd allow for 7.7% more capacity in a pack with minor adjustments. There's enough head space, we've learned from Tesla hackers.

 

[Cloxxki]

Nope, still makes no sense.
You give 550kW battery output, 120kw charge input. Where does the 102.4kW come from? Why would you call that a 'capacity'? When is Power ever a capacity?
What the heck does 100/18650 mean? 100 kWh (Model S) divided by a battery size (volume?)?

Care to try again?

Thank you kindly.

102.4kWh, of course. Surely you recognized the figure being so well versed in Tesla tech? Having so many disgruntled reply to get into, I got more sloppy with my typing that usual.

I will say this and then give up on explaining stuff to you.
>What the heck does 100/18650 mean?
Current 100 nominal pack made up of of 18650's.

 

[Cloxxki]

That rumored 85 pack may be the new "standard range" S/X pack with unaltered typical range. Just a significant reserve to prevent 100% charges (similar to the software limited packs we had), but used to prevent noticible battery degradation. In case any degradation is measured, some reserve is brought into play. Easy. That's just my speculation, I'm not giving anyone credit for hypothesizing that before me.

 

[R.S]

A measuring cup versus a scale precise to 0.01gram... I know which I'd take to get cell measurements for a complex shape or lack of calipers. It's precise enough to (somewhat) grade precious metal coins.

But how would you catch that excess water w/o spilling it? And then there is surface tension and things like that, so those .01 grams won't really be necessary.

 

[R.S]

Seeing that @Cloxxki is basically making my point again and again (as well as going on to making some interesting new ones), I am encouraged to try one more time.

@R.S @Topher

OK, let's - for the sake of argument - forget two flammable topics. They are not relevant to my thinking at all.

a) Let's forget Elon said anything, OK? It doesn't matter what he said about 100 kWh, for my argument. He has said nothing that we can rely on and let's just forget that soundbite.

b) Let's forget the 130 kWh rumor too. Let's be like it never happened, can't trust it even if it did, doesn't matter for my point in the least. I know I liked to toy with it, but it is a red-herring. Let's forget it.

OK, fair enough?

I hope that allows you see my real thinking here:

1) I believe 2170s has been found to be the optimal size for a cell, for Tesla, at this time. I believe this is more than just a cost-optimization, I believe it is an overall optimization. Whatever they learned (together with Panasonic), they put into it.

2) There may or may not be chemistry optimizations from the get-go, on the 2170. I am confident there are chemistry optimizations eventually, if not from the beginning. But be that as it may, they don't matter for my initial point.

3) I believe it is possible 2170s, even without any chemistry benefit, can fit more kWh in the same space as 18650s. Why? Because I believe Tesla has been able to lessen the amount of "scaffolding" inside the battery.

4) Given the optimization in point 1), I believe Tesla has also found 2170 to be a more optimal size for this. I.e. less wasted space compared to 18650s when considering how they can pack and heat manage them.

Basically my thinking is: Bigger cells means more chemistry and less metal structures taking space (and weight). It also IMO (I speculate) likely means a more optimal heat-management structures have been made possible (not just considering how to fit cells separately like a puzzle to a rectangle, but considering all the other elements as well how they fit optimally).

To sum it up: I think the 2170s, together with Tesla's and Panasonic's other advancements in battery making for that cell size, mean they can pack more kWh into a space than with 18650s.

Add to this the fact that the cells are higher, so assuming they fit, they will through that also pack more into the same square-footage, and that IMO Tesla is more likely to focus on chemistry improvements for the 2170s than what I assume are dead-end 18650s, I find it very likely Model S/X will get significant range and kWh (and possibly performance) upgrades from 2170s as soon as Tesla can ramp that up without harming Model S/X/3 sales...

The role of the 18650s I expect will be to maintain some Model S/X models for the time being, and while some intermediate update to those packs is possible (that "75" 85 kWh pack may be a somewhat new development?), I am expecting the next big thing to be with 2170s...

Sure all of that could be, but there is no way to really prove it, or to take any conclusions from it. It's all based on speculation w/o any real evidence to back it up.

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...

Like my plush unicorn speculation it's cool to speculate about, but it really doesn't lead somewhere. The OP did calculations based on what we know, you only assume some things and then draw conclusions from it. Just take your bullet points and replace "I believe" with "I don't believe" and suddenly the conclusions change. But the bullet points stay as valid as before.

 

[AnxietyRanger]

Sure all of that could be, but there is no way to really prove it, or to take any conclusions from it. It's all based on speculation w/o any real evidence to back it up.

Of course it is speculation. Only time will prove the speculation either correct or not (probably).

The OP made calculations, but offered no perspective on these packaging benefits the 2170s might employ - instead parroting the potential anti-sell line of 2170s only being about cost.

We have heard from several Tesla communications over the years that the 2170s were totally not only about cost, but about the optimal form-factor overall. I think this is wise to keep in mind, not parrot the cost-line without question.

 

[R.S]

Of course it is speculation. Only time will prove the speculation either correct or not (probably).

The OP made calculations, but offered no perspective on these packaging benefits the 2170s might employ - instead parroting the potential anti-sell line of 2170s only being about cost.

We have heard from several Tesla communications over the years that the 2170s were totally not only about cost, but about the optimal form-factor overall. I think this is wise to keep in mind, not parrot the cost-line without question.

Well, we know that the cells don't really hold more energy per volume and we know that w/o cooling the bigger cells can't be packaged more closely, than the smaller ones. That's just a mathematical problem. So the only reason why they could offer more energy density per volume would be cooling, which again should be harder with bigger cells. Now surely it could be that there is less cooling, but they could also do that with the 18650s.

The mass factor might be different though and a slightly larger cell might need less casing, since the modules would be shaped more like a cube. In conclusion any positive difference should be relatively small, at least based on what we know now.

 

[AnxietyRanger]

I'll try to give this a point-by-point go, not to argue you, but to document how I see our agreement/disagreement as well as clarify my speculation some more:

Well, we know that the cells don't really hold more energy per volume

Irrelevant to my speculation because I never claimed they did - assuming by volume we mean volume of chemistry inside. (Volume of supporting hardware may be a different thing as you agree in the last point.)

I do speculate 2170-based packs can hold more of that volume in the same footprint, though (and eventually may of course see chemistry improvements also, but that is beside the point for now IMO).

we know that w/o cooling the bigger cells can't be packaged more closely, than the smaller ones.

Irrelevant, because my speculation is that they can be cooled more efficiently, possibly because of a more optimal shape and improvements in pack design overall.

So the only reason why they could offer more energy density per volume would be cooling, which again should be harder with bigger cells.

I don't think we know it is harder with bigger cells. I (and some others) speculate the 2170 size was chosen in part because it would be more optimal to cool rather than the other way around.

The mass factor might be different though and a slightly larger cell might need less casing,

I agree this is one area where a difference can be made. That and the added height of the cells packing more vertically.

In conclusion any positive difference should be relatively small, at least based on what we know now.

I disagree that we know that. I think the positive difference overall might well be double digit percentages.

I am happy to agree to disagree.

 

[Topher]

I believe 2170s has been found to be the optimal size for a cell, for Tesla, at this time.

Until you say what it optimized FOR, this is pretty meaningless. Many people assumed not too long ago, that the 2170 was optimized for energy density. Turns out, not so much. The 2170 form factor (but not chemistry) is shared with the Powerwalls. Is it Optimized for that as well, what design requirements do they share?

I believe Tesla has been able to lessen the amount of "scaffolding" inside the battery.

Meaning? We have discussed cooling, and that would push the other way, what else is there that depends on cell size? Any evidence for this?

Bigger cells means more chemistry and less metal structures taking space

Maybe, pressures increase with volume, so the case may need to be more robust. Even so, the case is not a large percentage of the volume of the battery.

Thank you kindly.

 

[AnxietyRanger]

Until you say what it optimized FOR, this is pretty meaningless. Many people assumed not too long ago, that the 2170 was optimized for energy density. Turns out, not so much. The 2170 form factor (but not chemistry) is shared with the Powerwalls. Is it Optimized for that as well, what design requirements do they share?

First of all, I am offering my theory and speculation. I fully agree we do not know yet.

I have had no opinion on 2170 chemistry personally, ever. I do however think that saying 2170 is only about cost is simplistic and likely falling for Tesla's anti-sell.

Where does the cost benefit come from? Easier packaging with less "scaffolding"/kWh sounds like a plausible part of this to me. So I think this is the area they have optimized with the cell-size: how to fit cells to a pack and manage heat, what is an optimal size and setup for that. (In addition to other possible properties.)

Meaning? We have discussed cooling, and that would push the other way, what else is there that depends on cell size? Any evidence for this?

That is the disagreement. I believe it is possible 2170s allow Tesla to implement more compact/efficient heat management.

Maybe, pressures increase with volume, so the case may need to be more robust. Even so, the case is not a large percentage of the volume of the battery.

I agree a bigger percentage would come from an ability to pack cells more tightly, which in turn would come from - in my theory - more advantageous cell-size for packing and heat managing cells.

Let's not forget the height difference either. That allows making more use of vertical space.

So these are the three things that in my theory add up before we even consider possible chemistry advancements:

1) Less container material when less cells do more
2) Higher cells for more use of vertical space
3) A more optimal cell-size for heat management, can be packed more tightly

 

[stopcrazypp]

3) A more optimal cell-size for heat management, can be packed more tightly

I think this last one is the one that most people pushed you back on. 2170 has less surface area per given volume (which is theoretically worse for heat dissipation). A larger cylinder like 2170 is also slightly less efficient when doing an extremely tight packing into a module (just from basic geometry; the claims about either size being easier for coolant piping design haven't really been fully justified).

For #1 I would put an asterisk: * assuming cell wall thickness remains the same. This may not necessarily be true (as pointed out for example for minimal pressure resistance and structural rigidity requirements).

 

[AnxietyRanger]

I think this last one is the one that most people pushed you back on. 2170 has less surface area per given volume (which is theoretically worse for heat dissipation). A larger cylinder like 2170 is also slightly less efficient when doing an extremely tight packing into a module (just from basic geometry; the claims about either size being easier for coolant piping design haven't really been fully justified).

I understand that, however my speculation is the basic geometry angle is misleading. First of all is the common sense reason: Why would Tesla come up with a new cell that doesn't allow them to pack them up more tightly, but less tightly instead? Wouldn't the Occam's razor here be, obviously Tesla has come up with a design that can be packaged more tightly?

Second is that basic cell geometry is not the only thing that is dictating cell placement anyway. Already in the current packs the cells are not packed as tightly as possible, because there is all that "scaffolding" there. My speculation is 2170 is a more optimal size that allows the requisite "scaffolding", while minimizing the space the "scaffolding" needs as well as miniziming other wasted space.

In my speculation the cell-size is not simply about how to best manufacture a cell on the cheap, but what kind of cell is the most efficient to pack. I think the 2170 size has allowed Tesla to a) maximize vertical space, b) go for bigger possible container that still works chemistry-wise (so less container material), c) find a size that when packed, leaves optimal space for heat management.

I don't claim any particular details on how this is achieved. This is my thinking and speculation - and to me it would make sense that Tesla would optimize pack packaging.

And as mentioned, this is not just my speculation either, here is one other though I came across this after I had already formed my own opinion:

Tesla's 21-70 Vs 18650 battery cooling principles. (possibly derpy analysis). • r/teslamotors

Considering the newer format batteries have a larger radius, this will mean they can be packed more closely together while maintaining a similar radius of curvature in the coolant lines. If this was the case the coolant lines would cover a larger area of each batteries circumference. Therefore the coolant will be able to more effectively cool the larger battery as it has a greater contact with the coolant lines. By having more effective cooling the batteries in each battery line can have a smaller distance between them. Consequently you can achieve a much higher packing fraction with larger radius batteries while maintaining adequate cooling. The higher packing fraction means there is less wasted space in the battery module, and thus you can squeeze more battery density into the same foot print.

For #1 I would put an asterisk: * assuming cell wall thickness remains the same. This may not necessarily be true.

Of course.

 

[AnxietyRanger]

There is also this interesting comment on the Reddit thread:

There are pictures of the new pack showing it has a large cooling plate with vertical cooling fins that fit in between the battery segments. The glycol is circulated through the bottom cooling plate instead of between the cells themselves, allowing a denser structure since a fin can fit in less space than a coolant system.

Could Tesla eliminate the need for the coolant lines entirely and simply pack the 2170s as tightly as possible and use a coolant plate with coolant fins between the cells?

I don't claim to know. Just thinking out loud.

 

[transpondster]

There is also this interesting comment on the Reddit thread:



Could Tesla eliminate the need for the coolant lines entirely and simply pack the 2170s as tightly as possible and use a coolant plate with coolant fins between the cells?

I don't claim to know. Just thinking out loud.

but it is center of the cell that gets hot Thermally conductive separator with hierarchical nano/microstructures for improving thermal management of batteries