LFP Cybertruck

Bill906

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Right. But then you need four casting machines and then the machines to put the four pieces together so...
True... But what if the part you're making is symmetrical in a way that the same part could be used on the left side and the right side, or front and back. That would probably make the part less efficient than if it was made specifically for one side and the press would have to make multiple cycles to make one vehicle... Just a thought.
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firsttruck

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Tesla Cybertruck LFP Cybertruck one-bat-Screenshot_20220524_211743




But it does mean that there is structure is in the ribs and not the battery. It means the pack wastes some of its mass specifically on structure instead of batteries.

-Crissa
If the picture is accurate to rib details it shows them to be non-continuous. I would think a structural rib would be continuous. Also the height of the rib seem too short ( only 1/2 to 3/4 height of case ).

The ribs in the picture might be more for thermal cooling and as separators so individual cells are not directly pressed against each other.

I have seen several designs where packs of prismatic cells had separators (non-thermal type) between each cell with whole row of cells compressed in line.
 

Ogre

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Having ribs in the case does not mean the assembly is NOT structural.
My understanding of what makes a structural pack is that the batteries are part of the structure.

In this case, it looks very much like the ribs are the structure and the batteries are just dead weight.

BYD Blade cells are long and rigid which means they can be aligned to enhance the structure of the pack. 4680 cells are tall and cylindrical and when they are encased in resin become a structural honeycomb.

This pack looks like the batteries are supported by the rib structure.

Though I don’t think it much matters here because these are for heavy equipment and the extra weight won’t be a problem.
 

firsttruck

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Do you need to compress LiFePO4 cells?
Lack of compression can lead to LiFePO4 battery cells damage such as swelling and premature battery failure. Properly increasing external pressure can effectively extend the life of LiFePO4 battery cells.
https://energiepanda.com/how-to-compress-lifepo4-battery-cells/

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Do CALB LFP cells need to be compressed?
Data sheets for CALB cells require compression; Aluminum case cells have the same internals with a different case... it seems logical that compression would also be recommended here. Data sheets for prismatic cells (i.e. Higee) list compression values for internal testing.16 abr 2020
https://diysolarforum.com › threads › lifepo4-battery-b.

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Primastic aluminum cased LFP cells - do they require compression?
https://groups.google.com/g/electrodacus/c/FsPX025N2GQ

.....
Dacian Todea Jun 24, 2021
to electrodacus
Barry and Peter,
Obviously cells will work even without any compression but cycle life is dramatically reduced by a factor of at least 2 or 3x Compression is need only on the wide side of the cells. to keep the cathode and anode tightly packed. Bellow is a open Winston LiFePO4 cell but the construction on those CATL, EVE, Lishen ... cells is the same.

Tesla Cybertruck LFP Cybertruck unnamed%20(2).jpg?part=0



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LFP Cell Compression || The What Why How & Very Important Considerations || Step-By Step Tutorial
Aug 5, 2021
HighTechLab

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** also has chart of prismatic LFP cycle life vs compression pressure

Why compressing battery cells is (not) worth it - Here is what I found... Should you compress you battery cells or not? After having a look at the new updated specs of the battery cells, it clearly shows compressing the cells will prolong their life. But how do you do it and is it worth it? I did some digging and here is what I found so far.
Dec 26, 2020
Off-Grid Garage

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LiFePO4 Battery Compression, Fixture, and Assembly - What's the Deal?
Today, we're going to talk about battery pack assembly. What is compression and is it actually required? If fixture is so important, why don't many commercially-made battery packs seem to have it? What about stress on the terminals caused by normal expansion and contraction?
Sep 17, 2021
LithiumSolar

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firsttruck

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My understanding of what makes a structural pack is that the batteries are part of the structure.
I agree 100%. "batteries ARE PART of the stucture"

Does not mean 100% of structure.

Probably should not count as structural if batteries contributed only 1% of structural strength.

But if batteries contribute 20% or more it should count.
 


rr6013

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Except the people they sold the first LFP batteries in a region. It was like the one time, they asked some people to take delivery of LFP instead of what they ordered.

But yes, they give a range, not a wattage. They never say which formula is in them. They gave up giving a wattage back in the Model S.

Also... the 4680 structural packs are weird because they're not full of batteries, at least not according to the sample packs we saw at the Cyber Rodeo. They might also be doing something with voltage, too.




-Crissa
That YTube segment is programmatically interesting but proceeds to throw away all the value accumulated sticking to ‘status quo’.
Tesla charge connector is rated up to 900v. So future.
No disagreement with his rationality but its not got that Tesla brazen confidence.
BMS is my BIG”?” whether it programmatically able to drive larger, higher pack sizes AND meet specs for safety, orthogonal charge network implications and performance constraints downstream battery pack level.

SO a better engineer more knowledgeable about battery, batt chem, BMS, chargers and knock-on ramification building out compliant 2170/4680 at voltage increase is in-play.

The battery pack will self-assemble into a structural unit, so that’s a non sequitur. Tesla can offset struct variance between 2170.v.4680 with diff top sheet and/or encasement chem.

At the end of the development cycle, mid supply constraints and SOP Cybertruck anything that rises to % efficiency is gold treasury in the vaults for Tesla.
 

rr6013

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Doubt LFP will make it into CT any time soon. This is the very beginning of LFP research and it has potential to get close to lithium batteries eventually but won’t be for a few years. Maybe Tesla will make even bigger 6990 LFP cells down the road.
WHAAA? At what size volume do we get to the equivalent of a crate of landmines under our asses?

Already we have known risk of wildfire 18650 LiON packs going up in smoke, then where there’s smoke…
 

charliemagpie

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I couldn't read it… I don't want to, lol.

Got as far as the three 3 bullet points:

1. "Our source says .......—We have made this up

2.
Did Tesla .... to remind Detroit automakers who rules the EV market?
.......... Creating an arrogant Tesla

3. Why not cut the Cybertruck from the future product lineup? Because, pride before practicality, particularly when you have all that market cap.
… More denigrating words.


There is nothing to see here… move on.
 
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Tinker71

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Right. But then you need four casting machines and then the machines to put the four pieces together so...

...Why not just the one casting machine?

Another advantage of the gigacasting is that with every time they replace the die, they can iterate the part they're making. The vast majority of the machine and its hard, heavy steel, doesn't need to be replaced.

This is a move to make cars cheaper in perpetuity, basically.

-Crissa
You would not necessarily need 4 presses. Run 200 ( or some # )of each quarter casting and switch dies to run the other 3.

If the rear casting on the CT takes a 9000T press I would imagine to cast a semi rear or front in one piece would require a lot larger press. While technically feasible this would be quite a leap. The heavy duty nature of a semi will make this even more challenging because the thickness of the casting would grow proportionally to the increased payload of the semi. The exoskeleton of the CT reportedly works in conjunction with the cast front rear and structural pack. Would the body of the semi be able to do the same? I doubt to the same degree.

I also doubt the semi will be completely rigid like the CT. There will be little flex between the cab and the dual rear axles.

I suspect the semi will get some pretty tradition high strength steel box beam frame with smaller mega castings integrated for attaching the motors and drives.

There are surprisingly so many players in the EV truck world. Bollinger really? Telsa's real advantage will eventually be their head start in battery production and of course FSD.
 

firsttruck

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You would not necessarily need 4 presses. Run 200 ( or some # )of each quarter casting and switch dies to run the other 3.
...

Changing dies on a machine that large and complicated is a non-trivial task.
Probably cost significant amount of money and time.

Giga-casting machine is much larger and more complicated than standard automotive sheet metal stamping press. Giga-casting dies will be much more complicated & more more expensive than sheet metal dies.
 


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Tinker71

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If is is a huge deal to change out dies it might make sense to do larger runs. Storage might become a problem at some point.
 

rr6013

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Tesla Cybertruck LFP Cybertruck 18AE83F4-8CB2-4BED-9A4C-3FD398DAE582

This photo teaches that Tesla casting its motor assy together with the inner wheel well is inevitable.

A one piece structural motor assy,wheel well casting is another step away from “parts”. Its less assembly. And it invites innovation solving axel shaft angle at max droop(read limiting factor).

Interestingly, it frees Tesla from Double wishbone rear suspension enabling trailing arm.
 

firsttruck

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18AE83F4-8CB2-4BED-9A4C-3FD398DAE582.jpeg

This photo teaches that Tesla casting its motor assy together with the inner wheel well is inevitable.

A one piece structural motor assy,wheel well casting is another step away from “parts”. Its less assembly. And it invites innovation solving axel shaft angle at max droop(read limiting factor).

Interestingly, it frees Tesla from Double wishbone rear suspension enabling trailing arm.

Very interesting.

Where is the picture from (link)?

Is there more info about it?
 

Crissa

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If is is a huge deal to change out dies it might make sense to do larger runs. Storage might become a problem at some point.
They filled up all the green space at Fremont as they were making them before they were using them. Rows upon rows of castings!

-Crissa
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