My take on the new 100kWh pack

[Dithermaster]

The new cooling system could help improve Supercharging a lot.

New doesn't more "more". To pack more cells they probably actually reduced the size of the cooling system (while still keeping it as good). So don't expect Supercharging to improve.

 

[-=buzz=-]

A possible reason for the unusually high range improvement is, that due to the increased number of cells, the current load per cell has been reduced by roughly the same 10-15%. This should result in lower voltage sag.
For max power this has the effect, that the same 1500/1600(?) amp load should be provided at slightly higher voltage, which increases total power. -> Happy 0-60!
But for the normal driving load this means that, beside the higher capacity from the additional cells, the same power can be provided at a lower current. This not only reduces heat loss throughout the powertrain, but allows to extract more energy per cell*! -> Compunded range increase!

Does anyone have data on the voltage sag at various C-rates on the actual Tesla cells?


* -> same Ah * higher Voltage= higher Energy

 

[emir-t]

A possible reason for the unusually high range improvement is, that due to the increased number of cells, the current load per cell has been reduced by roughly the same 10-15%. This should result in lower voltage sag.
For max power this has the effect, that the same 1500/1600(?) amp load should be provided at slightly higher voltage, which increases total power. -> Happy 0-60!
But for the normal driving load this means that, beside the higher capacity from the additional cells, the same power can be provided at a lower current. This not only reduces heat loss throughout the powertrain, but allows to extract more energy per cell*! -> Compunded range increase!

Does anyone have data on the voltage sag at various C-rates on the actual Tesla cells?


* -> same Ah * higher Voltage= higher Energy

Totally agree with this. Might I add it will mean less strain per cell so cells will be healthier in the long run. I don't know if it is more power to actually put the same instant strain on cell and get higher amperage and the same voltage sag, or the same amperage but lower voltage sag. I'm sure they've done the math.

A couple of videos from the first page seem to show at max amperage for P90DL (1500amps, ~6C) BMS shows 315V instead of 403V. So a huge 85-90V sag. However cells regain voltage very well after the instantenous current draw as I recall from various tests performed on Model S cells at TMC.

 

[hiroshiy]

Yeah in my P85 Classic 1150A max, voltage sag is about 100V. So I'm pretty sure 100kWh pack will have less voltage sag, feeding higher voltage x 1600amps from the battery.

 

[seclinton]

Thank you, very informative. How does one learn about batteries like yourself?

- I've been involved with batteries for over 15 years and have built cell factories in both China and in Michigan (thanks Obama). Your task to figure out which one. Let's just say I worked in France on a joint venture too.

Is it your profession? Are you a scientist?
- yup it's my profession, and I'm an engineer and both process and quality with a degree in chemistry.

A few questions;

• By additive do you mean anode material(graphite) or electrolyte?

- anode. Effectively the Li-ion cell is limited in capacity by the materials in both the anode and cathode. Now while there is work being done on electrolyte, The big advancement is doping the anode with Si.

- electrodes are porous, made of coating a slurry of solvent and active material onto foil. Varying the thickness changes that porosity which in turn can increase or decrease capacity (also charging/ discharging efficiency, and rate)

• Also what is USL spec limit?

- we control the electrode coating by using spec limits USL= upper spec limit. I.e. If you increase the loading, you increase the theoretical capacity of the cell, a jump in mAh.

• By active material loading do you mean cells getting more dense per volume?

- yes, but maybe also a little thinner electrode with higher loading and lower porosity means longer wound length of components in the cell.

• How do you think they got around Si expanding and harming the cell when charged vs. discharged?
• Do you think they were not sure how it would affect the pack so they limited Supercharger capability for 90 packs, making them slower than 85 packs upon delivery and after enough data collected they updated it so 90's supercharge way faster now. (remember news from a few weeks ago?)

- how to conquer the Si swelling and cracking issue in he electrode due to swelling. Honestly I have no idea. Amprius is a company working on pure Si anodes. I'm waiting for the day this is perfected and battery capacity makes a huge leap forward.
But a little Si doesn't hurt so much when bound inside a carbon matrix. Remember the cell "jelly roll" is tightly wound.

However for the 100kWh pack discussion might I add news outlets say cells are the same. Addition of Si to the anode(thanks for correcting) was only on switch from 85 to 90 packs. As far as I interpret that made the cells go from 3100mAh to 3300mAh. So this was pack level innovation more than cell level. If the new pack was the same architecture but with more addition of Si resulting in 3700mAh cells, it would've been an amazing advancement.

However I'm fairly confident that they'll do amazing feats with the chemistry of 21-70. Current 18650's volume will increase 40%. With the current 3300mAh chemistry that takes them up to 4600mAh. With further advancements in cell chemistry they probably could achive 5Ah cells or maybe more.

- totally right and a great time to be involved in battery development.

 

[llavalle]

Very interesting. Do you know what factors differentiate the 1500 packs from the 1600 packs? Is it another fuse / contactor upgrade? Or is it a cell limitation? Or something else? I've been considering an L upgrade for my P85D and I'm curious what current limit it would be running.

No clues. From all the info I've gathered, no P85D ever went over 1500amps... it's a 90kWh pack thing. Might me a number of things : cell fuses, cell limitation, cabling size, etc...

 

[tnt1971]

Anyone know if they increased the weight of the pack? I have an 85D and overall I love the car. One of my complaints is the weight of the vehicle. I know its CG is low with the pack in the floor, but if they keep making the car heavier by stuffing more and more battery cells in it then the handling will get worse plus it will chew up tires even faster.

 

[Saghost]

Anyone know if they increased the weight of the pack? I have an 85D and overall I love the car. One of my complaints is the weight of the vehicle. I know its CG is low with the pack in the floor, but if they keep making the car heavier by stuffing more and more battery cells in it then the handling will get worse plus it will chew up tires even faster.

AFAIK, there's no information out there yet on weight. However, if the guidance we're getting is correct - no new chemistry, but new modules with a more complex design and better packing density - then the car will almost certainly be heavier.

The only way it wouldn't be is if they somehow took enough weight out of the cooling system and pack overhead to compensate for the extra cell weight, which seems unlikely.

 

[bonaire]

The Vin # 168668 that was crashed had a sticker in it showing 100 pounds more. Presumably, an "early 100 kWh build with an out-of-series Vin #".

 

[Raven]

I'd like to know when the new 20700 cell format arrives and what the theoretical maximum range will be for that.

If the 18650 is near its peak, the only logical step is switch to the 20700 or introduce new chemistry.

 

[SomeJoe7777]

I'd like to know when the new 20700 cell format arrives and what the theoretical maximum range will be for that.

If the 18650 is near its peak, the only logical step is switch to the 20700 or introduce new chemistry.

An interesting side note to this is that it might be a good idea for Tesla to adopt an alternating technology step each time they redesign the battery pack. This strategy can lower development risks.

Intel does this with their CPUs. They follow a mantra called "tick-tock" where each technology iteration focuses on two unrelated and different areas.

The "tick" iteration is a new microarchitecture, such as better pipelining, more cache, more cores, better branch prediction, new instructions, etc. This new microarchitecture is then implemented in the same die size (such as 22 nanometer) as the previous generation of processors.

The "tock" iteration then takes the microarchitecture that was developed in the "tick" iteration and implements it in a smaller die size so that the clock speeds can go up and the power dissipation can go down.

The process then repeats for the next generation. This lowers their risk (and cost) of bringing a new CPU to market because they're not ever designing and manufacturing a CPU where everything is brand new.

Tesla should do the same thing with the battery.

The "tick" iteration should be a new cell chemistry, which gives higher capacity and range. This should be implemented in the same cells and battery layout as the previous battery generation.

The "tock" iteration should then be that same chemistry in a new cell format, new packaging, new interconnects, lower weight, better cooling, etc.

This allows continuous battery improvements at double the rate that actual chemistry improvements happen, and reduces the business risks because you have one proven technology to serve as a base for the new one (i.e. working battery layout, cell size and manufacturing, but with a new chemistry. Or working chemistry, with a new layout, cell size, and manufacturing).

 

[SarahsDad]

According to this Electrec article Tesla Model 3: P100D is a test bed for Tesla’s third-generation battery pack technology, the P100D battery is 4% heavier. If the older battery was 1200lb, that's only an additional 48lb. So if that's 78lb of battery, that means 30lb less of coolant/other stuff. Maybe they're implementing different coolant options like in this interesting article http://gm-volt.com/2016/08/26/new-tesla-p100d-battery-pack-conceptualized/.

 

[gerti]

Intel no longer uses "tick-tock" and instead switched to "Process-Architecture-Optimization".

 

[SomeJoe7777]

Intel no longer uses "tick-tock" and instead switched to "Process-Architecture-Optimization".

Yes, recently they added a 3rd optimization step. However, the purpose is still the same -- reduce development and business risks by not changing too many things at once.

 

[Dithermaster]

Yes, recently they added a 3rd optimization step. However, the purpose is still the same -- reduce development and business risks by not changing too many things at once.

That's exactly why GigaFactory is being build in "quads" and the tweaks discovered or conceived of from one feed into the next. Continuous improvement.

 

[TheJMan]

I was just about to post a thread on how many cells in the new pack, then I found this thread

I was thinking earlier, so if the pack has 11.1% more capacity does that mean there are 11.1% more cells
7104 / 100 * 11.1 = 788
7104 + 781 = 7892, exactly what the OP came up with with

Heres a question though, I always thought tesla was using 3.4Ah cells not 3.3Ah like being said here. 3.4Ah 18650 cells are the best atm right. Aren't they missing out on like 3% more capacity / cell here?