Rumor: Model 3 to use new 4416 battery cell

[Trancela]

More speculation: The reason the module can fit up to 25 groups (instead of 24) is that all modules contain 25 groups, but one is a spare, and not in the 96s loop. Assuming there is no way to remove or insert a group of cells, when one cell goes bad, the group is bypassed (or shunted after discharged) and the spare group in the module (or in another module) is spliced in to maintain the 96s configuration.

75 kWh / 4416 = 17 Wh/cell or 4.6 Ah. Add 6% for the unused buffer and you get 18 Wh/cell or 4.85 Ah.

 

[Doug_G]

Seems unlikely. That would result in an unbalanced pack.

 

[Trancela]

It's worth nothing that, from the Model 3 press kit, 237 Wh/mi wall-to-wheels is not correct. From the spec sheet, "30 miles of range per hour (240V outlet, 32A)" is 256 Wh/mi wall-to-wheels. So the wall-to-wheels difference vs. the S isn't as great as that calculator led on.

Charge energy for a cell is greater than discharge energy for the cell. Anywhere from 6% to 10% loss between charge and discharge of a cell. I wonder if the 237 Wh/mi is wall to wheel or battery to wheel?

256 Wh/mi wall to wheel translates to 237 Wh/mi battery storage to wheel.

 

[scaesare]

Just as I had speculated -- that the groups (not modules and not the 96s voltage) are smaller on the T3.220. @scaesare

Not sure why you're tagging me here.

Assuming the modules have fewer cells per group is kind of a no brainer. It was your conjecture that they were stuffing 18650 cells into 2170 cans that I found too much tinfoil-hat wearing to be plausible...

 

[Trancela]

Not sure why you're tagging me here.

Assuming the modules have fewer cells per group is kind of a no brainer. It was your conjecture that they were stuffing 18650 cells into 2170 cans that I found too much tinfoil-hat wearing to be plausible...

Because you were wrong. That was just one of the conjectures. "no brainer"? You brainlessly dismissed that they may stuff fewer cells in a group, thus implying they were using different sized modules.

 

[KarenRei]

Charge energy for a cell is greater than discharge energy for the cell. Anywhere from 6% to 10% loss between charge and discharge of a cell. I wonder if the 237 Wh/mi is wall to wheel or battery to wheel?

256 Wh/mi wall to wheel translates to 237 Wh/mi battery storage to wheel.

Except that the 237 Wh/mi figure was, as mentioned three times in my post to be clear, wall to wheels. Not battery to wheels. A) It was used in a comparison with known wall-to-wheels figures for S and X, and B) it was being used in code to calculate energy costs to the owner from wall charging.

237 Wh/mi is what you would have gotten had they met their Cd design goal of 0,21 rather than the achieved 0,23.

 

[scaesare]

Because you were wrong. That was just one of the conjectures. "no brainer"? You brainlessly dismissed that they may stuff fewer cells in a group, thus implying they were using different sized modules.

Nope.

 

[wk057]

How long before you do a Model 3 teardown?

How long before someone totals a Model 3 and @wk057 can get one at auction?

Might not even wait for auction... might tear down one of the ones I've reserved, whenever I get it that is.

Interesting. Why wouldn't they have just gone with 24 groups in all 4 modules?

The sides of the pack are shorter (between the wheels front to back) and the center is longer (no wheels in the way). 24 groups wouldn't fit on the sides, and 24 groups in the center would waste space. So, just two different types of modules. And yeah, they're yuuuuge.

What's your take on the high number of cells for the apparent capacity demand based on published range and leaked 237Wh/mi consumption? To me, the capacity seems to have a very significant reserve, or the 2170 cells are a terrible disappointment from a size or density standpoint. Something's up!
All about the range narrative, and packs holding its "new" charge for several years?

The 2170 cells in the Model 3 pack, based on my math, do not have the same volumetric energy density as the 18650s being used in the 75/90/100 S/X packs. My speculation is that they're using chemistry similar to the older 60/85 type packs. I base this speculation on my own longevity testing of both types of 18650 cells which has the older cells proving to have a much more robust cycle life than the newer higher energy ones. It would make sense to utilize the time-proven and more resilient chemistry in their new cells, at least to start.

Assuming the 237 Wh/mi number is right, then 310 * 237 = ~73.5 kWh, which seems close enough to the advertised 75 kWh when accounting for a small buffer. The 237 Wh/mi number is definitely not wall-to-wheels.

 

[MP3Mike]

The sides of the pack are shorter (between the wheels front to back) and the center is longer (no wheels in the way). 24 groups wouldn't fit on the sides, and 24 groups in the center would waste space. So, just two different types of modules. And yeah, they're yuuuuge.

Do the modules come out individually, or are they still in a single larger pack?

 

[KarenRei]

Assuming the 237 Wh/mi number is right, then 310 * 237 = ~73.5 kWh, which seems close enough to the advertised 75 kWh when accounting for a small buffer. The 237 Wh/mi number is definitely not wall-to-wheels.

Look, I read through the code on the page that that Wh/mi number came from: it was being used as wall-to-wheels. If it's not the actual wall-to-wheels for M3 (which it doesn't appear to be), it's simply wrong. It was being used for wall-to-wheels calculations. It was being compared to walls-to-wheels figures for S and X. It was supposed to be a wall-to-wheels figure.

And it would have been right, had M3 come in at Cd=0,21, which was the design goal. But M3 came in at Cd=0,23.

 

[Cloxxki]

The 0.237 seems to have lost relevance before we read it then.

@wk057 Interesting that you also consider the old chemistry robust. It's seen pretty high charging rates and no need for elaborate throttling, right?

To keep boasting about highest density seems a bit silly if they'd take a step back from the silicone adventure. The 10-15% gains seen in testing, rather 20% after the silicone era, could to be something for later cost savings, or a miraculous range upgrade still for Model 3/Y. Once the 18650's stop flowing from Japan, might S/X get the first upgraded 2170's? Pack sizes would then really hike up. A great way to keep S/X popular, make them seem like a sweet deal (more margin made on the pack, and getting 125-130kW at the same price? A good way to sell cars into regions where there is no reason to build (A lot of) superchargers yet. Providing they can grow S/X production capacity eventually. Little point to anti-sell 3 for the benefit of S/X if they can't make them any quicker. If true, a weakness in the Tesla armor.

 

[apacheguy]

Yeah, I think they returned to the older cell chemistry for the brand new 85 kWh packs:

Battery Charge Level Will Be Restricted

Would make sense for them to do the same with the M3.

 

[Cloxxki]

Wow, that would make the whole recent generation a formal fail? If the increased density on 2170 in tests were an extention of that, that line of development may have been scrapped as well?
100 packs heavily throttled (1.12C peak vs 1.44 in old 85 packs), smaller packs reverted to old tech...that'd be something...

 

[gregd]

Edit: Oh, I see where the 4416 number came from. Someone is bad at leaking information it seems... lol. It's not cell type, it's cell count. The Model 3 75 kWh pack is 96S46P, so, 4,416 cells.

In some circles, there is debate over the "Oxford Comma". We now have the "Tesla Comma". Please use it properly; it makes a difference.

 

[Reciprocity]

Could this mythical new cell actually be used in the Tesla Semi? Would there be an advantage to a larger cell for a much bigger battery pack. Almost like supersizing the 2170 into a 4416 where everything is basically just scaled up. Just spit balling here, I have no clue but I would like to think that the Teslanomics guy trusts his source. Maybe it was just bad information given to employees to see who was leaking information.

 

[wdolson]

Could this mythical new cell actually be used in the Tesla Semi? Would there be an advantage to a larger cell for a much bigger battery pack. Almost like supersizing the 2170 into a 4416 where everything is basically just scaled up. Just spit balling here, I have no clue but I would like to think that the Teslanomics guy trusts his source. Maybe it was just bad information given to employees to see who was leaking information.

JB Straubel has said that to balance energy density with cooling ability, the 2170 was the best fit cell size. That isn't going to change for the semi. At least the diameter won't. They could make the battery pack taller with a longer cell, but 4416 would be an unworkable geometry from a cooling perspective. Heat would build up in the middle of the cell.

The most likely answer is the 4416 is the number of cells used in one of the battery packs for the M3. That's at least in the ballpark of being a reasonable answer. It's also possible 4416 has nothing to do with the M3 and the whole story is made up by someone who heard something wrong.

 

[alloverx]

If they went back to a previous version of chemistry is that why the battery guy just left (if he was not simply tired/wealthy with shares)?

 

[aronth5]

The most likely answer is the 4416 is the number of cells used in one of the battery packs for the M3. That's at least in the ballpark of being a reasonable answer. It's also possible 4416 has nothing to do with the M3 and the whole story is made up by someone who heard something wrong.

This

 

[JeffK]

If they went back to a previous version of chemistry is that why the battery guy just left (if he was not simply tired/wealthy with shares)?

If anything he left because of missing internal deadlines.

 

[wdolson]

If they went back to a previous version of chemistry is that why the battery guy just left (if he was not simply tired/wealthy with shares)?

It's clear they are not going to settle long term on any battery chemistry currently available. New chemistries are coming and Tesla wants to be at the cutting edge of that wave.

If they decided to go back to an earlier chemistry, it's a temporary move until they can work out something better. If anything, they would need their battery experts more than ever.

Rather than any move on the part of Tesla to make the guy's job redundant, I suspect there was some falling out between Tesla management and the battery guy personally. Whether it was from missing a key deadline as @JeffK suggested or the guy didn't like working for Tesla and got a better offer, or something else, it probably had little to do with what chemistry is being used in the Model 3.