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Model S with 2170 cells conceptualized

Discussion in 'Model S: Battery & Charging' started by emir-t, Dec 12, 2016.

  1. emir-t

    emir-t Member

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    I'm sure you guys are bored with this topic over & over again but I found myself doing all sorts of calculations about the new 2170 cells in the Model S this morning and wanted to share my thoughts with you guys.

    First, the cell.

    - 2170 will have 45% larger volume than the 18650.
    - Chemistry has been improving at an average rate of 7% a year. Proof? Besides statements from Tesla execs, 2008 Roadster cells were 2100mAh, 2012 Model S cells were "rounded up" to 3100mAh and 2015 cells were 3300mAh.

    So a 2017-2018 18650 should have been ~3700mAh. Add to that the larger volume and we have a 5300mAh, 19,5Wh, our saviour 2170 cell.

    Next, the fitting.

    Fitting circles in a rectangle is a real challenge depending on configuration. Thanks to this website we can enter our specs and get the physical limits of fitting the cells in our modules.

    We can find out about the size of a Tesla Model S module here at this eBay listing.

    When we plug the data into the calculator, being generous and entering 18,5mm for cell diameter and 0,8mm for cells being apart(listing states 0,8mm tubing, that might have decreased with the 100 pack but we'll ignore it for now) , we get 552 cells possible to fit in a triangular pattern.
    [​IMG]

    Next, my P100D cell count estimation. I am "close to sure" on the new packs having 87 cells per group (13 more than before). How do numbers check out?
    - 87p96s = 8352 cells. We know Tesla uses the same cells and pack voltage has to be the same (so we're sure on the 96s part). With the 2015 3300mAh, 12,2Wh cells we get ~101,8kWh nominal capacity.
    - Pack's Ah rating is 287Ah. Multiplying that with Tesla's 6,14 c rate used for ludicrous accelaration we get 1762 Amps peak draw equating to about 540kW of power. Very consistent with findings, I'm convinced.

    Getting back to the circle fitting problem we see that Tesla has fitted 522 cells per module into a physically limited 552 cell area. They have stated this is the theoretical limit for now too. If it weren't for any chips or housing or glue or connectors or chips it could get 552 cells but it is getting 522 cells. So a utilization rate of 94,5%! Impressive.

    Off to 2170 calculations. I'll be generous again as I was with 2170 capacity estimations and assume a less efficient, 90% utilization on the pack as a larger cell could need more cooling although unlikely. I'm doing this so the results will be 'at least' that amount.

    So our calculator shows a possible 420, 2170 cells fitted into the same old Model S module.

    [​IMG]
    - 90% utilization would give 380 cells per module.
    - 380 * 19,5 = 7,4kWh per module.
    - Keeping the 16 module setup is a Model S P120D with 380 mile range and probably even faster accelaration.

    And remember this calculation is very modest on developments. So I wouldn't be surprised to even see a 130kWh pack in 2019. (A nominal capacity rating of 20Wh and 93-94% util. rate for the pack would easily make this happen) With the new cells even the 14 module current 75 setup is 100 kwh.

    So my guess for the Tesla battery lineup in early 2019;

    Model S & X;
    - 100 (62p, 84s)
    - 120kWh. (62p, 96s)
    Model 3;
    - 55kWh (37p, 84s) (~54kWh usable)
    - 70kWh. (37p, 96s) (~66kWh usable)

    Although I'm fiddling around with the idea that the Model S and Model 3 should be sharing modules as long as production streamlining and costs are involved but I can't come up with the math. They have to keep the 96s part same for voltage and change the parallel part also there's the size difference. Unless they drastically redesign their packs and use much more modules and reduce in-pack series configuration, they should be different modules unlike VW, Faraday Future's modular setups.

    Anyway, my .2c. Will be interesting to watch. Even though there are diminishing returns above the 100kWh battery I think Tesla will go for it because 1) they have to keep the high top margins and 2) why not?

    What do you guys think?
     
    • Informative x 4
  2. TonyWilliams

    TonyWilliams Active Member

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    They will save money with a physically smaller, lighter battery pack at the same capacities as today (60-100kWh).

    That's what I expect.

    The actual range of a 100D with a lighter pack will be further than the 100D current pack.

    Eventually, I'm confident that there will be 200kWh packs in cars, but that will be mostly to absorb 1-2MW charge rates... 3000 - 6000 mph charge rate... 50-100 miles per minute initially... hundreds of miles in a short amount of time.
     
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  3. bob_p

    bob_p Active Member

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    If Tesla can get 2170 batteries quickly enough, is it possible they'll delay introducing the 100D until they can build a battery pack with the 2170 batteries?

    Doing so would allow them to introduce the 100D with the cheaper, lighter battery pack - which would improve the performance of the 100D and allow them to price it closer to the 90D, while also possibly increasing their profit margin.
     
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  4. emir-t

    emir-t Member

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    Although it makes sense it seems more plausible to use them for the Model 3 as fast as they come considering the amount of preorders and pressure on Tesla. Unless they start getting them so early that it is even months before Model 3 production line is active. i.e. in 3 months.
     
  5. scaesare

    scaesare Well-Known Member

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    I'd say those are pretty reasonably estimates as to what the packaging for the new 2170's could look like, and the energy capacity possible. Well done and presented.

    I, for one, hope that Tesla does introduce >100kWh packs (Elon's earlier statements not withstanding). Lighter packs of the same capacity are desirable, but the range gain from a 400lb pack reduction will be nowhere are much as from 20% energy increase.

    And while ~300 mile ideal range is good enough for probably 80% of most driving needs, that remaining 20% needs to be addressed. Cold in many parts of the world reduces range by 30-50% during winter. Towing can increase energy usage by 2-3X. If you have a model X and want to tow your trailer in the North in December, stopping every 90 miles isn't just no fun, it's not really feasible.

    While the above factors are a minority of driving needs, if EV's are to eventually replace ICE vehicles, they will eventually be scenarios that need to be addressed.

    (I also blame you for the engineeringtoolbox.com rabbit hole I'm about to descend in to...)
     
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  6. emir-t

    emir-t Member

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    Teardown of new 100 kWh Tesla battery pack reveals new cooling system and 102 kWh capacity

    Wow I'm almost spot on after the teardown it seems. :)
     
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  7. MP3Mike

    MP3Mike Active Member

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    Highly unlikely almost all 2170 production is going to go to stationary storage and Model 3 battery packs until more of the Gigafactory gets up and operational. Do people really want to wait 9-12 months for a Model S 100D?
     
  8. Electric700

    Electric700 Active Member

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    That's what I'm talking about! :)
     
  9. TonyWilliams

    TonyWilliams Active Member

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    Bummer... I bet that the new 100kWh battery would be 84s, instead of the actual 86s that it is.
     
  10. R.S

    R.S Member

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    Well, they have already introduced the 100D, which will probably still have the old cells. But I doubt that the 2070 cells will be used in the 3, before they are used in the S and X. For two reasons.

    First, it makes the S and X cheaper, therefore brings in more cash. No real explanation needed here.

    Second, they don't have to align Model 3 ramp up with GF ramp up. It is much safer to ramp up production for the GF first, look if there are some unexpected problems and then ramp up the Model 3 and look for unexpected difficulties. Because if one of those two results in major delays, Tesla will have two massive production lines just standing there.

    With the X and S packs, they could just slowly phase them in and just don't tell the customers. Like they have done so many times before, with things like autopilot, or just new packs.
     
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  11. Dithermaster

    Dithermaster Member

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    There are probably one or two Model S or Model X cars driving around right now with hand-made prototype 2170 packs to prove out the Model 3 design. Perhaps even Model 3 motor and gearbox prototypes. Unlike body prototypes, drivetrain prototypes are going to be very hard to spot! Elon himself could be driving one and we'd never know. About the only visual clue would be if they put a big red e-stop button in the interior.
     
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  12. bxr140

    bxr140 Member

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    No.

    They got a surge off the 100D. Once they start putting 2170 into S/X, they'll get another surge.
     

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