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New 2021 Model S battery cells & packs

lolachampcar

Well-Known Member
Nov 26, 2012
6,105
7,441
WPB Florida
How does Tesla define "fully redesigned"? It seems the car, physically from the outside, is identical to the one that preceded it. In every single possible way. I'd be very wary of Tesla's loosey-goosey use of the term "redesigned". It seems marketing and bull***t have coalesced.
I've been crawling all over my Plaid and am amazed at just how much has changed with the car still looking very similar.

The body shape is similar but the panels are all different. Wheel arches have been pulled out and down. Tires are now better framed in low needing only minor lowering to be perfectly framed. The suspension is phenomenal. They have dramatically changed how they impart forward loads into the chassis and appear to have addressed some of the design issues that drove salt induced corrosion failures on the previous cars. Neutral throttle lateral grip is way up while "feel" is down from both the front and rear of the car. It seems like there is less rubber isolation in the tire to chassis path as I hear more tire noise than before but overall the car is much quieter. Driver position has changed dramatically. Instead of sitting in my old P90DL I feel like I am sitting on the Plaid.

I agree fully that the car appears the same but every one of my senses tells me it is a completely different car. If I could not see the car and could only go on my other senses I would recognize the BeV power delivery but would think it a completely different car.
 

emailforbrett

Member
Dec 22, 2020
164
500
Orlando
I’m sure this is a dumb question, but Chemical Engineering is not my forté.

Instead of cylindrical batteries, why can’t they make them rectangular cuboids (like 9v batteries)? With all right angles, it seems they could squeeze more surface area, ie more chemical energy, into each row and column of the battery packs.

67368B77-90E8-4389-806F-03751B1C9B88.jpeg
 
Last edited:

MorrisonHiker

Well-Known Member
Mar 8, 2015
10,336
10,162
Colorado
I’m sure this is a dumb question, but Chemical Engineering is not my forté.

Instead of cylindrical batteries, why can’t they make them rectangular cuboids (like 9v batteries)? With all right angles, it seems they could squeeze more surface area, ie more chemical energy, into each row and column of the battery packs.

View attachment 725431
The trend has been a move to larger and fewer cylindrical cells. If you open up a 9 volt battery, you will find it contains 6 cylindrical AAAA batteries.
inside-e1292823738808.jpg
 
  • Informative
Reactions: aerodyne

BM3B

“beaver”
Mar 8, 2019
842
1,055
Los Angeles, CA
I’m sure this is a dumb question, but Chemical Engineering is not my forté.

Instead of cylindrical batteries, why can’t they make them rectangular cuboids (like 9v batteries)? With all right angles, it seems they could squeeze more surface area, ie more chemical energy, into each row and column of the battery packs.

View attachment 725431
Two reasons:
1. The jelly roll (google "battery jelly roll")
2. Cooling (google "tesla battery cooling")
 
  • Informative
Reactions: Tigers

lolachampcar

Well-Known Member
Nov 26, 2012
6,105
7,441
WPB Florida
I find myself putting a lot more emphasis on the chemistry, anode and cathode performance over the physical packaging. I'm sure the change in cell size will bring value but it seems the larger package will need the benefit of improved cell design/performance to work within the current heat rejection scheme. I do not think you can work the current cell technology as hard as they are now using the larger cell format. Internal resistance will have to fall more before that is possible.

Any cell experts here????
 

miimura

Well-Known Member
Aug 21, 2013
6,698
6,546
Los Altos, CA
Lots of questions answered.
Summary:

The Tesla Plaid pack uses 7,920 18650 cells arranged in 5 modules that have an 72P22S arrangement each. (total of 72P110S)
Same BMS system as Model 3/Y. It is capable of sustained 2300A output at a max voltage of 462V (That's over 1 megawatt!).
Each module is 15 3/8" (390mm) long X 55 1/4" (1404mm) wide X 3" (76mm) high. If you include the coolant manifolds and lines, the width is 57 3/8" (1458mm).
This pack's data obtained from the BMS:
Beginning of Life Pack Energy: 99KWh
Nominal Energy Remaining: 32KWh
Nominal Full Pack Energy: 95KWh
 

MarcG

Active Member
Oct 29, 2014
3,881
5,439
San Francisco
I find myself putting a lot more emphasis on the chemistry, anode and cathode performance over the physical packaging. I'm sure the change in cell size will bring value but it seems the larger package will need the benefit of improved cell design/performance to work within the current heat rejection scheme.
This, plus agressive thermal management - which Tesla has done a great job with improving from the previous Model S.
 

Dave EV

Active Member
Jun 23, 2009
1,924
1,644
San Diego
I’m sure this is a dumb question, but Chemical Engineering is not my forté.

Instead of cylindrical batteries, why can’t they make them rectangular cuboids (like 9v batteries)? With all right angles, it seems they could squeeze more surface area, ie more chemical energy, into each row and column of the battery packs.
Non-cylindrical batteries are called prismatic batteries.

Basically everyone but Tesla is using large-format prismatic batteries. Mainly because they haven't figured out how to cost-effectively assemble packs made of lots of small cylindrical cells.

In theory there can be some energy density gains by volume by using a prismatic cell - but you usually need/want a bit of space around the cells, anyway, to make it less likely that you will have a run-away thermal event if a cell fails in a bad way or is damaged.

At the cell level, cylindrical cells are far cheaper to manufacture and since cost is a major limiting factor to EV adoption, Tesla has decided that cylindrical cells are the preferred format and that the 4680 has the best balance of cost, performance and safety.
 

emailforbrett

Member
Dec 22, 2020
164
500
Orlando
Non-cylindrical batteries are called prismatic batteries.

Basically everyone but Tesla is using large-format prismatic batteries. Mainly because they haven't figured out how to cost-effectively assemble packs made of lots of small cylindrical cells.

In theory there can be some energy density gains by volume by using a prismatic cell - but you usually need/want a bit of space around the cells, anyway, to make it less likely that you will have a run-away thermal event if a cell fails in a bad way or is damaged.

At the cell level, cylindrical cells are far cheaper to manufacture and since cost is a major limiting factor to EV adoption, Tesla has decided that cylindrical cells are the preferred format and that the 4680 has the best balance of cost, performance and safety.

Thank you. This makes sense. I figured cost may be a bit higher because the simple fact it is likely easier to create a long roll of the three layers (cathode, separator, anode) in cylindrical form than it would be to wind them in prismatic form. I knew the cylindrical cells were cooled with fluid between the curved outer surfaces, but I thought maybe they could leave a small gap between the flat surfaces of the rectangular cuboid shaped batteries.

I think the above is possible….more energy per total space occupied from rectangular cuboid batteries, but the cost increase negates any gain in stored energy.
 

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