Investor Engineering Discussions

[nativewolf]

Really it is just savings from the front casting, since the Model Y has always had the rear casting. (At least I think it did, originally as two pieces, and then replaced with a single piece; which would have had minimal weight savings.)

My guess is that the front casting saves 15-20 pounds. (But a whole lot of space, robots, welding, rivets, structural adhesive, etc.)

Thanks... interesting to see one when they finally come off the line. The more I studied it the more compelling it became so we just canceled our Y and decided to wait. I'm really waiting on my CT, the Y is for she whom must be obeyed.

 

[MC3OZ]

I wonder from time-to-time what is happening with the "mining" to extract Lithium from Clay.

Elon and Drew seemed reasonably confident on Battery Day.

I didn't expect that project to be quick or easy, but equally, I don't expect Tesla to give up.

My take on "massive scale" is, battery raw materials are unlikely to stop "massive scale" being achieved, because supplying them will be part of the plan.

 

[MP3Mike]

Troy is claiming that the 828 cell pack is equivalent to the LR and that they remove 2 bandoliers of cells for the Standard Dual Motor variant. So it would only have 690 cells.

 

[mongo]

4680 design seems to me heavily influenced by the desire to only cool on the ends. This in my estimation was(is) most of the end delay in ramping production. They couldn't find a way to safely cool the packs withought cooling the middle of the cells.

If that's the case, and the end-cooling dream is now somewhat out the window, stands reason there's room to stretch the cell length for truck/robotaxi/semi pack design.

In addition to assuming they could solve end-cooling, I'm sure they also thought CT pack design would be 100% locked in by 2Q22. That delay also gives them time to pivot on design if they feel it's considerably more optimal for the long haul.

How so?
Tabless cuts electrical path and self heating way down while improving the thermal path. Cooling on the sides is more protected and energy efficient than bottom cooling which has losses to the environment and increased risk of damage. Plus height increase and complexity of flow channels.
Implementation wise, the heat/ electrical path is the circumference on the side at the bottom and the center button on the top. The bottom is also the vent and not a uniform suface to mate to along with need for a gas escape path.
Before bottom cap install:

Spacer/ insulation/ vent path:

 

[mongo]

Exactly, the bottom voids are also much too large to be cooling passages. "Bottom cooling" was entirely created by speculation.

Unless you prefer laminar flow over turbulent (which would be a bad choice for a cooling system).
Do I care enough to calculate the volume and fluid mass those voids would take? Not yet I don't.

 

[JRP3]

Sandy talks to DuPont about battery adhesives, materials, and immersion cooling. Not directly Tesla related but interesting.

 

[mongo]

There was another odd article on CT about using Trucks to truck water down a mountain, use regen to charge their batteries and use that charge to do other things.

New Electric Trucks-For-Hydropower Scheme: Look Ma, No Dams

Fleets of electric trucks could be deployed in low impact hydropower systems that deploy existing roads instead of new infrastructure.

cleantechnica.com

I like the concept, but we could even improvise on that on having a chain of large buckets of water sliding down a mountain on rails, and generating electricity through regen and sending it to grid. It is a closed loop, where the buckets are roped up the mountain using a fraction of electricity it generates while coming down. The question is will this be more efficient than a standard damn and turbines?.

Trucks eliminate the need to find a suitable place to dam, the impact of the new flooding, and allows the full height change to be used.
Low maintenance/ higher setup cost setup would be a pipeline from the headwaters to a turbine. Possibly multiple levels with turbines/ tanks/ overflows to reduce head pressure.

 

[mongo]

I’m pretty sure it costs more than $25 for them to manufacture. Lots of copper, a pretty compact high capacity transformer, and the charge computer in the cable all cost a little bit of money. There is a good reason they have multiple adaptors for the various voltages and plug styles rather than just making a separate cable for each.

Agree on price > $25.
Wall connector does not have a high capacity transformer. Only a current sense ones for GFCI and something for electronics power.
Does have high capacity contactors.

 

[Buckminster]

 

[MP3Mike]

Jordan Giesige of The Limiting Factor confirmed with Tesla engineers at Cyber Rodeo that 4680 cells in the structural battery pack are cooled both via the side cooling ribbons and via heat wicking from the pack's metal bottom to the side cooling ribbons:

"What Tesla delivered on" | The Limiting Factor (10:12)

"Next, the structural battery pack. Now one thing that I predicted before battery day was that Tesla would use plate cooling for the 4680 battery cell, and they would fully maximize the utility of that tabless electrode, because the heat would be wicked away directly through the bottom of the battery cell.​

​

"But what we've seen over the past year, and what was confirmed at Austin, is the cooling ribbons that run down the sides, and I did confirm this with one of the Engineers there, the cooling that happening on the sides actually conducts to the bottom of the battery cell.​

​

"So it is taking advantage of that tabless electrode. Now besides the heat wicking that's going on, the tabless electrode also reduces the amount of heat generated because there's less resistance, because there's more metal.​

​

"So the combination of those two things, that big chuck of metal, and the fact that the cooling ribbon cools the side of the can, and that cooling conducts to the bottom of the battery cell, and those two things in combination are so effective that you don't need plate cooling at the bottom.​

Here's the video: (cued to comments quoted above)

As Sandy would say, the Model Y "is a symphony of engineering"

Cheers!

I'm pretty sure that someone is misinterpreting stuff in there. I think the Tesla engineer was saying that the heat exits the tabless electrode into the bottom of the cell can and travels up the side such that the cooling is happening from both the side and bottom of the can with the cooling ribbons just touching the side of the cell can. There is no way they are using the packs metal to cool the cells, as you would likely never be able to heat them during winter and you would have major problems. (In fact at least one of the pictures made it look like they was an insulating pad between the pack and the cells.)

 

[mongo]

Jordan Giesige of The Limiting Factor confirmed with Tesla engineers at Cyber Rodeo that 4680 cells in the structural battery pack are cooled both via the side cooling ribbons and via heat wicking from the pack's metal bottom to the side cooling ribbons:

"What Tesla delivered on" | The Limiting Factor (10:12)

"Next, the structural battery pack. Now one thing that I predicted before battery day was that Tesla would use plate cooling for the 4680 battery cell, and they would fully maximize the utility of that tabless electrode, because the heat would be wicked away directly through the bottom of the battery cell.​

​

"But what we've seen over the past year, and what was confirmed at Austin, is the cooling ribbons that run down the sides, and I did confirm this with one of the Engineers there, the cooling that happening on the sides actually conducts to the bottom of the battery cell.​

​

"So it is taking advantage of that tabless electrode. Now besides the heat wicking that's going on, the tabless electrode also reduces the amount of heat generated because there's less resistance, because there's more metal.​

​

"So the combination of those two things, that big chuck of metal, and the fact that the cooling ribbon cools the side of the can, and that cooling conducts to the bottom of the battery cell, and those two things in combination are so effective that you don't need plate cooling at the bottom.​

Here's the video: (cued to comments quoted above)

As Sandy would say, the Model Y "is a symphony of engineering"

Cheers!

Not sure "both" is correct.
The cells are only cooled by the side ribbons, there is no bottom plate like Sandy supposed. The heat flows through the bottom, but the bottom is only cooled through conduction to the side.
The side ribbon directly removes heat via contact with the side of the cell (through a dielectric sheet).

 

[mongo]

I’ll throw my engineering guess that this.
The model Y was designed for 2170s and the 4680 gives 10mm less vertical height in the pack available. Maybe bottom plate cooling just wouldn’t fit.

Tesla never showed bottom cooling.
The cell bottom is not uniform and is also the safety vent.
Bottom plate cooling increases losses to the environment. Also more susceptible to road debris damage.
Bottom plate is more complex to manufacture than the U turn ribbons.
2170 packs have modules with top and bottom layers along with redundant pack top and cabin floor that all take space.
Model Y has a false floor made of foam blocks, if Tesla needed space, it's available. Austin is all new tooling.

 

[JRP3]

The cell bottom is not uniform and is also the safety vent.

What are your thoughts on the material for the bottom cell holders? I assume some sort of plastic but they are thicker than I would have expected, taking up some space. Maybe for increased distance from the pack bottom for better impact protection and maybe insulation.

Model Y has a false floor made of foam blocks

Do you mean the original Y, and do you have a reference pic? Somehow I missed that.

 

[mongo]

What are your thoughts on the material for the bottom cell holders? I assume some sort of plastic but they are thicker than I would have expected, taking up some space. Maybe for increased distance from the pack bottom for better impact protection and maybe insulation.

Yeah. Vent channel for thermal event, crumple zone for bottom impact protection, air gap for insulation.

Do you mean the original Y, and do you have a reference pic? Somehow I missed that.

I think it's shown in the Munro tear down also.

Tesla Model Y body arrives as Giga Texas hinting at structural battery pack production

 

[JRP3]

I think it's shown in the Munro tear down also.

It looks like it's only a small section near the fire wall, probably to make a smooth angled transition for the foot well, doesn't seem to continue across the whole pack.

 

[mongo]

It looks like it's only a small section near the fire wall, probably to make a smooth angled transition for the foot well, doesn't seem to continue across the whole pack.


View attachment 795753

Pretty sure it's in rear footwell also. Foam plus seat brackets could give up a few mm if needed.

 

[JRP3]

I agree they have more vertical room to play with, I think the limitation would be the height of the rear electronics "penthouse" and how it impacts rear seat height. Floor height has to accommodate the rear HVAC ducts so that might be the purpose of the foam spacers, and they might not be needed in the rear.

 

[JRP3]

Here's the Munro video you referenced with a good look at the front foam spacers, exactly as you described.

This video shows the rear carpet still in place and it only seems to drop down a small amount after the front seat cross member so you're probably correct about rear foam spacers as well.

 

[mongo]

I'll be sure not to!

Now... about the fact that Gen1 chargers were technically spec'ed to accept 277V A/C as an input...

Line to neutral on 480V wye.

 

[scaesare]

Line to neutral on 480V wye.

Right. Seeing how 208V (phase-to-phase on a delta) was verboten, I thought it would be funny.... lol