A look at the new Tesla cells

11919 Views 124 Replies 14 Participants Last post by Kevin Sharpe, Dec 1, 2017

PhantomPholly

Discussion Starter · May 28, 2017

2170 cells replaces 18650 standard at the Gigafactory.

Doubtful they will be available to DIY community, though. The big boys will probably contract full production.

81 - 100 of 125 Posts

Solarsail

· #81 · Nov 27, 2017 (Edited)

Kevin Sharpe said:
I thought the 21700 in the Model 3 was 'confirmed' as ~4.6Ah given we 'know' the long range version has 4416 cells and a capacity of either 74kWh (here) or 80kWh (here)

The 3.4Ah capacity is for a 18650. Now since the 2170 is 1.466x the volume of the 18650, one would expect the proportional capacity for the 2170 to be 4.98Ah. But if the capacity is confirmed at 4.6Ah, then that is a step backward! (Note that the 'chemically usable' volume proportion of the 2170 is actually higher - about 1.5x, which implies a capacity of 5.1Ah.)

The T3 LR pack is estimated at 78 kWh nominal (and 74 kWh usable). 78 / 4416 / 3.6 = 4.9Ah -- which I believe is more likely (than 4.6Ah).

Kevin Sharpe

· #82 · Nov 27, 2017 (Edited)

brian_ said:
Since Model 3 modules built of the 2170 cells are presumably superior to the 18650's in current production models, my guess is that modules which you salvage from Model 3's after they go into actual production will be the same as what will be used in the Semi (and presumably Roadster 2). Or at least the cells in them will be the same.

The Tesla Model 3 battery capacities announced by Elon Musk suggest that the 2170 is 'simply' a repackaging and cost reduction exercise. Clearly a 200kWh battery will not fit in the Roadster 2 without some major improvements in energy density (at least x2). It's hard to know whether Tesla can deliver this in two years, but given Musk has never met a date I guess two years could turn into five and then maybe it's possible

Kevin Sharpe

· #83 · Nov 27, 2017 (Edited)

Solarsail said:
The 3.4Ah capacity is for a 18650. Now since the 2170 is 1.466x the volume of the 18650, one would expect the proportional capacity for the 2170 to be 4.98Ah. But if the capacity is confirmed at 4.6Ah, then that is a step backward! (Note that the 'chemically usable' volume proportion of the 2170 is actually higher - about 1.5x, which implies a capacity of 5.1Ah.)

The T3 LR pack is estimated at 78 kWh nominal (and 74 kWh usable). 78 / 4416 / 3.6 = 4.9Ah -- which I believe is more likely (than 4.6Ah).

Thanks, that makes a lot more sense

brian_

· #84 · Nov 27, 2017

Kevin Sharpe said:
Clearly a 200kWh battery will not fit in the Roadster 2 without some major improvements in energy density (at least x2).

While the Semi's battery size and packaging are mysteries at this point (it could have five tons of battery), that's a good point about the Roadster - it's hard to see that body with double the battery volume (or mass) of a Model S.

electro wrks

· #85 · Nov 27, 2017

brian_ said:
While the Semi's battery size and packaging are mysteries at this point (it could have five tons of battery), that's a good point about the Roadster - it's hard to see that body with double the battery volume (or mass) of a Model S.

The Tesla Semi main designer, Jerome Guillen, said in a recent presentation in Europe that the Tesla truck weighs no more than a diesel truck. If you take a modern diesel semi (also designed by a team lead by Jerome Guillen when he worked for Daimler/ Freightliner) and pull the engine:https://freightliner.com/demand-detroit/engines/dd16/ ; transmission:https://freightliner.com/demand-detroit/detroit-dt12-transmission/ say ~1000# of tanks, radiators, non-fuel fluids, and other ICE related equipment; and 200gal(~1400#) of fuel. You save ~6000# (if I haven't left any thing out). So how much energy will ~6000#(~2700kg) of batteries give us?

brian_

· #86 · Nov 27, 2017 (Edited)

electro wrks said:
The Tesla Semi main designer, Jerome Guillen, said in a recent presentation in Europe that the Tesla truck weighs no more than a diesel truck.

Good info from Guillen.

The weight has been missing from most of the fluff publicity around the Semi.

electro wrks said:
If you take a modern diesel semi (also designed by a team lead by Jerome Guillen when he worked for Daimler/ Freightliner) and pull the engine:https://freightliner.com/demand-detroit/engines/dd16/ ; transmission:https://freightliner.com/demand-detroit/detroit-dt12-transmission/ say ~1000# of tanks, radiators, non-fuel fluids, and other ICE related equipment; and 200gal(~1400#) of fuel. You save ~6000# (if I haven't left any thing out). So how much energy will ~6000#(~2700kg) of batteries give us?

And it's even worse than that, because the electric truck still needs a cooling system (although lighter than the diesel's), and - much more importantly - that 2700 kg would need to include four motors. You could delete the diesel's differentials, roughly offsetting the reduction gearing that goes with the motors. Then there's the electronics... four inverters, the chargers, etc.

This could also mean that the claim of matching diesel weight is just bunk.

To be fair, this claim was likely for a shorter-range version, not the 500-miler.

aeroscott

· #87 · Nov 27, 2017

Everthing can be made lighter with less vibration . Battery packaging will save weight over the multiple car batteries . Small improvements in batteries
are a given.
That's not " just bunk" it's good engineering.

brian_

· #88 · Nov 27, 2017

aeroscott said:
Everthing can be made lighter with less vibration .

I'm not sure what components might be part of this "everything", since the Semi is using the same hitch, tires, wheels, suspension, and frame design as a conventional design truck. Are the frame rails lighter? That could make a few kilograms of difference, I suppose.

aeroscott said:
Battery packaging will save weight over the multiple car batteries . Small improvements in batteries
are a given.
That's not " just bunk" it's good engineering.

Continual improvements are good engineering. Whether the "same as diesel" claim turns out to be the result of improved design, or is just bunk, remains to be seen...

electro wrks

· #89 · Nov 27, 2017

brian_ said:
This could also mean that the claim of matching diesel weight is just bunk. To be fair, this claim was likely for a shorter-range version, not the 500-miler.

It could be. Although in the presentation, I believe he only talks about the longer range Semi. To clarify, he does parse the weight discussion by saying the Semi has the same cargo capacity as a diesel semi. Hear for yourself at ~ 4:30:
https://electrek.co/2017/11/26/tesla-semi-vp-trucks-electric-presentation/

Solarsail

· #90 · Nov 27, 2017

My guess is that the unit weight for the modules, including packaging, will be 4.5 to 5.5 kg/kWh. A 1MWh pack is out of question, including by volume. A 300 kWh pack will weigh about 1,500 kg or 3,300#.

Karter2

· #91 · Nov 28, 2017 (Edited)

Kevin Sharpe said:
The Tesla Model 3 battery capacities announced by Elon Musk suggest that the 2170 is 'simply' a repackaging and cost reduction exercise. Clearly a 200kWh battery will not fit in the Roadster 2 without some major improvements in energy density (at least x2). It's hard to know whether Tesla can deliver this in two years, but given Musk has never met a date I guess two years could turn into five and then maybe it's possible

I doubt Musk is in any rush to alter/improve the cell performance just yet.
They are having enough problems getting the cell/pack production up to speed as it is (one of the main bottlenecks in M3 production delays), so any more changes in that department are very risky.
Tesla has also recently lost several of their key tech guys on the battery development side including Kurt Kelly the department head , and Jon Wagner , head of battery technology !

brian_

· #92 · Nov 28, 2017 (Edited)

electro wrks said:
To clarify, he does parse the weight discussion by saying the Semi has the same cargo capacity as a diesel semi. Hear for yourself at ~ 4:30:
https://electrek.co/2017/11/26/tesla-semi-vp-trucks-electric-presentation/

Thanks for the clarification.

That's a huge difference. There is no single value for maximum truck weight (it depends on axle count, axle spacing, which road, where...) so it's easy to compare an eight-ton diesel tractor and an 10-ton electric tractor and say they have the same payload because they can both haul a 30-ton trailer.

Commercial trucks in North America have their tare mass and maximum gross loaded mass posted on the side of the truck. Some which operate over wide areas have quite a list of gross combination weight values listed, each annotated with where it applies. The highest values (typically a Canadian federal limit of 62,500 kg - 137,789 lb - for a B Train Double) are more than 1.5 times the lowest values (such as the general US federal limit of 80,000 lb or 36,288 kg). Even within a single jurisdiction, a truck licensed for 40 tons and one licensed for 60 tons are not wildly different in their own weight.

On the other hand, Guillen refers to only a single GVW limit (the US federal value) and says that they are aiming to have the same payload... so nothing has actually been achieved, and we're still talking about aspirations. Even the 800 kilometre (500 mile) range is expressed as a target, not an actual specification. By the time these numbers get from the Truck VP to the Supreme Leader (Musk), of course they become absolutes.

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Kevin Sharpe

· #93 · Nov 28, 2017

Karter2 said:
I doubt Musk is in any rush to alter/improve the cell performance just yet.

I agree... hard to imagine how we get from here to a 200kWh Roadster 2 battery in two years

electro wrks

· #94 · Nov 28, 2017

brian_ said:
On the other hand, Guillen refers to only a single GVW limit (the US federal value) and says that they are aiming to have the same payload... so nothing has actually been achieved, and we're still talking about aspirations. Even the 800 kilometre (500 mile) range is expressed as a target, not an actual specification. By the time these numbers get from the Truck VP to the Supreme Leader (Musk), of course they become absolutes.

The trucking industry is a careful, conservative lot. Tesla is not going to be able to fool them for long, if they can't deliver the goods. I suspect the better cheaper batteries that we speculate must be in the Semi and R2 are here, with full production coming sometime later. I also suspect Tesla isn't bragging about it so as to not tick off the people buying the Model 3, that has the older batteries.

Duncan

· #95 · Nov 28, 2017

One of the things to bear in mind when looking at larger battery packs is that on the current packs a lot of the weight is armour - and also structural weight

When you go larger the structural weight and especially the armour weight do not have to go up anywhere near as fast as the "active" weight so a battery with ten times the capacity may only have six or seven times the weight

aeroscott

· #96 · Nov 28, 2017

That sounds right to me

electro wrks

· #97 · Nov 29, 2017

Here's some quick(some might say frantic!) info on the better batteries that could be in the Semi and R2 starting at ~1:20: https://www.youtube.com/watch?v=MUaEfDkzQfs

aeroscott

· #98 · Nov 29, 2017

Elon said $65/Kwh in materials and at another time said well under $100/Kwh for finished batteries.
It will be closer to the $65. Commodity level manufacturing which by it's nature will be continually refined in a never ending quest for improved production.
He also said the through put is like a machine gun and they slow it down so you can see the cells.

Kevin Sharpe

· #99 · Nov 29, 2017

aeroscott said:
Elon said...

I think that's the problem

All of this would be so much more believable if Tesla actually demonstrated a significant improvement in capacity rather than a change in packaging which, while important, cannot deliver the 200kWh Roadster 2 battery

aeroscott

· #100 · Nov 29, 2017

If the batteries are as cheap as I think and Elon hinted at, and mining and refining and production taking advantage of $.05/w solar cells . That will drive the cost of the batteries lower without improving cell energy density. Energy density is a given with time at this point.

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