ALL CyberTruck discussion

[mad474]

Sorry, simply had to ...

 

[JRP3]

Disagree with @Artful Dodger, can't imagine why the newest Tesla vehicle would use the oldest battery pack architecture. Plus the costs they are targeting are surely counting on some battery breakthrough. Also as Mongo said you don't get cold rolled stressed skin stainless steel construction from castings.

 

[Sean Wagner]

Cybertruck AWD ($50K version) will have the Raven powertrain from the S/X. Those are 18650 cells from Panasonic in Japan. There is also spare capacity on the S/X line right now, since they are down to 1 shift per day. At least all the powertrain components are available in volume now.

Even if Tesla plans for a build rate of merely 100'000 Cybies per annum, only Nevada will be able to supply the cells and packs in sufficient quantity. Let's not forget that the newer cells are more weight-efficient, and with the required kWh per truck, that matters too.

We've gone over the reasons Models S & X are staying with the 18650s for now.

While the manufacturing setup should indeed be uniquely simple. It's just that the design and engineering phase need to be completed. I do hope the finished truck's looks will be just a little less stark - it would age a lot better.

 

[JRP3]

I do hope the finished truck's looks will be just a little less stark - it would age a lot better.

Rather difficult to predict. This may be the new trend setting look for the future.

 

[Artful Dodger]

Are you sure about that? The presentation specifically stated that all versions of Cybertruck would be able to charge at 250+kw.

Or are you saying that the limitation in the S/X from charging at 250+kw is not associated with the batteries, but something else?

Yes, even the most modest 75 KWh Model 3 pack can charge at 250 KW. The larger 100 KWh S/X pack is only limited by its old-style cooling (wiring is trivial, likely already updated in S/X Raven), which will be redone (and likely in common) for Cybertruck.

Its the chemistry that's more interesting. Right now, even if Tesla goes with there existing NCA formula, they can achieve the stated charge rates. If they update to the newer Dahn 'secret-sauce', they'll beat today's spec.

Cheers!

 

[MP3Mike]

Yes, even the most modest 75 KWh Model 3 pack can charge at 250 KW. The larger 100 KWh S/X pack is only limited by its old-style cooling (wiring is trivial, likely already updated in S/X Raven)

I don't think it is the cooling. Most of the time the 3 is supercharging it is actively heating the battery. And the 100 pack has updated cooling from the original packs.

 

[Artful Dodger]

Disagree with @Artful Dodger, can't imagine why the newest Tesla vehicle would use the oldest battery pack architecture.

Imagine these reasons:

• They have spare capacity for S/X packs at Fremont
  • won't limit Model 3/Y producition if they ship CT AWD 1st
• their architecture is easily updated for improve cooling
  • have to do this work already due to Plaid S
  • already announced for Summer 2020
• Model 3 architechture is already on it 2nd iteration
  • new Grohmann machine builds SR+ and LR packs

But you seem to be stuck on opitimizing the CT as a new product. I promise you Elon is not thinking about that; his primary concern is finding the fastest way to the market with a new product that's better, not perfect.

Tesla will reuse existing powertrains, the 2 that exist now. First will be Model S/X for AWD; then next will be Model 3 for RWD as new capacity becomes available (when Shanghai and Berlin come online)

Plaid will be the third version simply because that powertrain is still in development, and will be released initially in the Model S (Supercar).

If its any comfort, Ford used the same Coyote V8 drivetrain in the Mustang GT and the F-150 Raptor pickup. FCA uses their 6.3L Hemi in several sedans and pickups. Reusing powertrains across car and truck lines is common industry practice, and is the OBVIOUS next move for Tesla to expand their addressable market.

Cheers!

 

[Artful Dodger]

Even if Tesla plans for a build rate of merely 100'000 Cybies per annum, only Nevada will be able to supply the cells and packs in sufficient quantity. Let's not forget that the newer cells are more weight-efficient,

Panasonic has spare cell capacity in Japan for 18650s. There is no spare capacity for 2170 cells in Sparks, and with Model Y and Semi coming in 2020, there will not be any spare capacity for a while.

Jack Rickard proved that the 18650s and 2170s have identical specific capacity. He did a video earlier this year providing the measurements. Both cells deliver 250 WHr/Kg. This video was discussed here at TMC.

People constantly overestimate what Tesla can do in the short term (1-2 yrs), while underestimating what they can do long term (5-10 yrs). Remember in mid-November while well-respected members were speculating about 'flying' cybertrucks, or silly submarines? Meanwhile, Tesla themselves actually produced the first prototype only 2-3 WEEKS before the reveal.

Tesla will REUSE POWERTRAINS. There is no other way to market without an unacceptably long development cycle.

Bonus Estimate: Based on known data for Model 3 LR RWD weight and acceleration, Cybertruck RWD (using Model 3 powertrain) will produce 386 hp and weigh 5405 lbs

Cheers!

 

[JRP3]

But you seem to be stuck on opitimizing the CT as a new product. I promise you Elon is not thinking about that; his primary concern is finding the fastest way to the market with a new product that's better, not perfect.

You seem to be stuck thinking of the CT as a soon to be released product. In 2-3 years cell production will have significantly increased. You know Elon's primary concern is iterating as fast as possible, but not necessarily rushing a new product. We don't even know if S/X will be using 18650 3 years from now. The obvious next move is to use their newest cells in their newest vehicle. I'll predict it will be an NMC chemistry not NCA, or maybe a "C" free version. Don't forget battery day is still coming up.

 

[MP3Mike]

magine these reasons:

• They have spare capacity for S/X packs at Fremont
  • won't limit Model 3/Y producition if they ship CT AWD 1st

Panasonic has spare cell capacity in Japan for 18650s.

Where are you getting information that there is spare 18650 capacity? Yes, Tesla reduced the number of S&Xs that they make but they also eliminated all but the 100kWh versions. (And the smaller packs were the majority of what they were making before.)

I think they are still using ~100% of the 18650 capacity that is available to them. (Which is why they said that there is a backlog of S&X orders and they are filling them as fast as they can.)

 

[MC3OZ]

My hunch is the Cybertruck and Plaid Model S/X using new battery modules..

IMO the next step is all Model S/X using new modules.

18650 production in Japan can be re-purposed to make 2170 cells for Tesla energy.

 

[AudubonB]

As long as we're discussing the Way Out There manufacturing ideas, I wonder what the metallurgical characteristics are for built-up (ie, 3D printed) large scale 30X stainless is? Knowing something about the crystalline structure of austenitic (and martensitic) iron alloys, I have a lot of difficulty envisioning it can bring the malleable....rigid....even "stainless" attributes that traditional cold-rolling imparts to these melds.

I am all but completely clueless, however, in how these translate when one sputter-forms these materials. And all this is moot if it cannot be done - in the short- and medium-term - in fast enough time to be considered for mass production of, e.g., a CT.

 

[Artful Dodger]

It wouldn't be exactly the same though since you can't make cold rolled stainless from a casting. Strength and hardness could be cut in half resulting is thicker/ heavier walls. That said, they could go stainless on the vehicle lines for longevity.

@mongo @AudubonB

Yeah that's right, Tesla wouldn't use the cold-rolled process for casting stainless steel bodies. Instead, they'd likely prefer an open-cell metal foam, for example the stainless steel in this 2019 study:

Frömert, Jan, et al. "Investment Casting and Mechanical Properties of Open‐Cell Steel Foams." Advanced Engineering Materials (2019): 1900396.​

From the Abstract: (emphasis mine)

"This study presents a novel manufacturing process for open‐cell stainless steel foams using a modified investment casting process and a novel approach to identify transitions between elastic‐plastic, plateau, and densification region in the stress–strain history of compressed foams, based on its strain and structural hardening behavior.

"The influence of microstructure on the mechanical properties under quasi‐static compression loading (plateau stress, energy absorption, and strain hardening) of austenitic (AISI 304, 316L) and super duplex (AISI F55) stainless steels is investigated.

"The manufacturing process yields open‐cell foams with relative densities in the range of 14–20%, solid struts being circular in shape and defect‐free surfaces.

"Among the manufactured open‐cell steel foams, F55 foams with fine‐grained duplex microstructures show highest yield strength, strain hardening, and energy absorption with a sufficient ductility.​

Figure 1. Macrostructure of electropolished open-cell stainless steel foams: a) specimen for compression tests (3030 mm2) and b) SEM micrograph of a single strut.

More from the Paper: (emphasis mine)

4. Conclusions

Open-cell stainless steel foams were manufactured using a modified investment casting process and characterized regarding the microstructure and mechanical properties. The following conclusions can be drawn from this study:

1. The investment casting process is suitable to produce open cell stainless steel foams with different chemical compositions not especially designed for casting.
2. Determination of characteristic points during compressive deformation in materials with high strain hardening is possible by analyzing the strain hardening behavior.
3. The energy absorption in steel foams increases with increasing strain hardening, yield strength, and relative density. In contrast, the energy absorption efficiency decreases with increasing strain hardening.
4. Minimizing near surface and edge defects, porosity in the micrometer range or embrittlement in the struts result in a significant increase in the mechanical properties compared to sintered steel foams.

So, overall superior properties with this metal foam vs cold-rolled SS plates (ie: higher strength/weight ratio, stiffness). Have you ever seen a production method more ripe for optimium design via FEA? Auto? Meet CAD.

EVENTUALLY, open-cell metal-foam SS body casting could become the host matrix for lithium ion energy storage within the structure of the vehicle body itself (no separate bty pack). Yeah, that's one of those "10-year" goals.

Send me a PM if you need access to the full paper, or find more related articles with Google Scholar.

Cheers!

 

[Artful Dodger]

Where are you getting information that there is spare 18650 capacity? Yes, Tesla reduced the number of S&Xs that they make but they also eliminated all but the 100kWh versions. (And the smaller packs were the majority of what they were making before.)

You'll have to do the math on the product mix. Also Panasonic was looking to convert Japanese 18650 lines to 2170 production. You don't do that with a process running at capaciy.

I think they are still using ~100% of the 18650 capacity that is available to them. (Which is why they said that there is a backlog of S&X orders and they are filling them as fast as they can.)

There's only 1 shift of S/X running. The final assembly line as a minimun could go 2x capacity by simply adding a 2nd shift. Sub-assembly supply lines are easier to duplicate, and generally take less time than major components.

I think this is where they build the AWD CT (same powertrain) and eventually the Tri-motor CT (which will share powertrain with Plaid Model S expected for Summer 2020)

Cheers!

 

[EVNow]

I think this is where they build the AWD CT (same powertrain) and eventually the Tri-motor CT (which will share powertrain with Plaid Model S expected for Summer 2020)

Are you saying CT production capacity will be ~80k a year ?

I hope it will be more like 10k/wk.

 

[Artful Dodger]

Are you saying CT production capacity will be ~80k a year ?

I hope it will be more like 10k/wk.

No, I'm saying Tesla could use the spare capacity on the S/X line to start AWD CT production VERY quickly (much sooner than "late 2021). The actual production numbers for the AWD variant would be something like (total S/X installed capacity) - (current S/X run rate). Then more capacity could be added with new lines (even by using more Sprung structures), then using the Model 3 infrastructure separately to add the RWD variant.

No paint, little body (just laser-etch, bend, and weld), maybe some hull coloring but I think even that'll wait for now and people can always use wraps until then.

Cheers!

 

[EVNow]

No, I'm saying Tesla could use the spare capacity on the S/X line to start AWD CT production VERY quickly (much sooner than "late 2021). The actual production numbers for the AWD variant would be something like (total S/X installed capacity) - (current S/X run rate). Then more capacity could be added with new lines (even by using more Sprung structures), then using the Model 3 infrastructure separately to add the RWD variant.

No paint, little body (just laser-etch, bend, and weld), maybe some hull coloring but I think even that'll wait for now and people can always use wraps until then.

Cheers!

I think they still need to figure out how to make stainless steel body in bulk.

I don't know how easy / difficult it would be to switch between S/X and CT or how long that would take. For eg., can they switch between two shifts, daily or would they switch once a week ?

Ofcourse, the earlier they can make and start selling CT, even in smaller quantities, the better it is.

ps : I expect a F150 to somehow defeat CT and pull it once the production & sale starts

 

[heltok]

 

[Artful Dodger]

The author says "as the vehicle speed increases, the coefficient of drag is actually going down, so this is some clever stuff." and "at 88 mph, it gets down to about 0.38 in reality, I suspect at high speeds this car is probably closer to 0.3"

CD = 0.40 @ 40 mph, CD = 0.38 @ 88 mph. Compare this to the realworld drag coefficient of a F-150 class pickup of 0.45 which also has a larger frontal area.

The author expects Cybertruck to achieve 0.30 at high speed. Wedgie-for-the-Win.

 

[EVNow]

Tesla will reuse existing powertrains, the 2 that exist now. First will be Model S/X for AWD; then next will be Model 3 for RWD as new capacity becomes available (when Shanghai and Berlin come online)

I think there is little chance of Musk wanting to carry technical debt into a new product.

I could envision this - if S/X sales was tanking. But it seems to have stabilized / slowly increasing.