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Is a 110kWh battery possible today?

Discussion in 'Model S: Battery & Charging' started by beegee, Jun 15, 2013.

  1. beegee

    beegee Member

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    I was reading that the Model S uses 3100mAh type 18650 cells. I searched the cell type and found that there are cells rated to 4000mAh available.

    Figure the number of cells:
    3.7v x 3.1 Ah = 11.47 Wh 85000/11.47 = 7410 cells (give or take)

    Now the interesting part:
    3.7v x 4Ah = 14.8 Wh 14.8 x 7410 = 109668 or ~110kWh

    Seems quite possible then by just using the higher capacity cells.
     
  2. deonb

    deonb Active Member

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    Thoretically, but Tesla doesn't just use stock 18650 3100mAh. There are a few changes to make it automotive grade, which requires a dedicated production run. There are also various safety and reliability tests that need to be run first. Lastly, Tesla doesn't exactly follow factory specifications when it comes to charge rate etc... The heroics that the SuperCharger perform with the 3100mAh as is quite impressive.

    As such, it's not just a matter of running over to Radio Shack and picking up the new cell - it's quite a process to upgrade. So I would think they wouldn't go after every interim release of a new battery, but rather go for larger changes to get more investment bang for the buck. So my guess would be that the next Model S battery model would be something over 133kWh (thus 4.8 Ah per cell). 133 kWh would allow them to market the car with a 400 mile EPA range rating.

    PS: You should also look at this thread.
    http://www.teslamotorsclub.com/showthread.php/17456-Amazing-Core-Tesla-Battery-IP-18650-Cell
     
  3. Larry Chanin

    Larry Chanin Model S Perf Sig 1055

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    Many of us believe that Tesla will be demonstrating battery swapping on June 20th.

    For demonstration purposes it would be more interesting if Tesla put together some battery packs at over 100 kWh.

    As deonb states its theoretically possible with some additional effort.

    Following beegee's methodology and using the published specifications.

    3.6v x 3.1 Ah = 11.16 Wh, 85000/11.47 = 7616 cells

    3.4v x 4Ah = 13.6 Wh, 13.6 x 7616 = 103.5 kWh.

    This would yield a nice 22% increase in capacity. One issue is that the 3.1 Ah cells weigh about 44.5 g, and the 4.0 Ah cells weigh about 54 g, or about 17.6% heavier. This would be equivalent to adding the weight of a passenger distributed in the floor. I'm guessing that the suspension would be able to handle this added weigh.

    This would certainly be cool for demonstration purposes, and maybe for a small scale swapping operation. As deonb points out, depending on what Panasonic is charging for the new cells, the 22% improvement in capacity might not be sufficient to justify full commercialization. However, for leasing in a small scale swapping operation maybe it would make sense.

    Larry
     
  4. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    I think Larry's note about the weight is important. The Model S is already heavy.

    29.2% density gain for 17.6% weight gain and 9% voltage drop. It seems to me that these aren't really Model S material. Maybe Model S Performance Plus Plus edition where they wouldn't mind increasing the current.

    These are more suited to Gen 3 (assuming they can lower the price) or grid-connected storage, where the overall improvement to energy density and specific energy would significantly outweigh the importance of the voltage drop.
     
  5. PhilBa

    PhilBa Active Member

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    Another way to think about this is to consider what is a reasonable cruise range. Is 250ish miles a good size? I actually think 200 miles is OK. That still beats the h*ll out most of the EVs out there. It's an energy density vs total weight trade off. If a manufacturer can reduce the weight/size of their battery pack and keep the amount of energy the same, that's where I can see it going. Don't forget those heavy batteries require energy to haul around so making the car lighter will improve cruise range. If the Model S was 20% lighter but still had an 85KWH battery, it would go farther.

    And by the way, I would be shocked if Telsa hasn't anticipated energy density improvements in their manufacturing plans.
     
  6. twinklejet

    twinklejet Member

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    I wonder if Tesla will eventually have the same problems with Panasonic that Apple did with Foxconn...
     
  7. Larry Chanin

    Larry Chanin Model S Perf Sig 1055

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    Care to elaborate how the relationships are analogous? Panasonic is not producing Model Ss overseas under dubious working conditions. They are merely supplying Tesla with a modified commodity battery in bulk that Tesla assembles into battery packs in its factory in the US.

    How does that relate to the Apple - Foxconn relationship?

    Thanks.

    Larry
     
  8. twinklejet

    twinklejet Member

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    I meant supply capacity. For some product launches, Apple was unable to meet initial demand since Foxconn couldn't churn them out fast enough. What happens to Tesla's production line, capacity, etc. if Panasonic can't keep up with future Tesla growth? :) That's what I'm referring to.
     
  9. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    My question for Elon Musk would be. "Given that success for Gen 3 would lead to enormous cell manufacturing demand, have you had any discussions with Panasonic about building a cell manufacturing plant in the USA?"

    As I understand it, the cell fabs for the cores that Tesla buys are fully automated. So, they'd have to build another fab, but the automation means that a ramp-up should be relatively easy
     
  10. Larry Chanin

    Larry Chanin Model S Perf Sig 1055

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    #10 Larry Chanin, Jun 16, 2013
    Last edited: Jun 16, 2013
    Thanks for the response.

    A few days ago Panasonic announced that it had produced 100 million cells for Tesla. Their factory can do 300 million per year. Then of course the all important fact is that Tesla uses commodity cells, so in a pinch I'm pretty sure that they could bring on other commodity suppliers.

    The superiority of this commodity approach was undoubtedly lost on Fisker and their relationship with battery maker A123. :wink:

    Larry
     
  11. jdevo2004

    jdevo2004 Member

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    I remember reading somewhere on this forum that a quarterly statement from Tesla indicated that they have two battery suppliers.

    I also find it highly likely that Tesla will be demonstrating battery swapping with standard 85 KWh and future ready +100 KWh batteries this week.
     
  12. raymond

    raymond Member

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    That could perhaps also make the process cheaper by using e.g. Chilean Lithium being shipped in raw form to CA, instead of shipping cells from China.

    OTOH, most Tesla's won't be sold in the USA so perhaps it's better for TSLA to focus on what they do best and keep cell manufacturing at Panasonic. This also makes TSLA more flexible in shifting to a new chemistry or supplier.
     
  13. EVNow

    EVNow Active Member

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    Lithium is just 4% (IIRC) of a Li Ion Battery.
     
  14. Larry Chanin

    Larry Chanin Model S Perf Sig 1055

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    Regardless, battery pack assembly is going to occur at the factory for the foreseeable future. So it would still cut expenses if battery manufacturing occurred in the US. Maybe Elon could start a "bidding war" among forward-looking states looking to expand economic development.

    Larry
     
  15. JohnQ

    JohnQ Active Member

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    Struggling to understand the cost savings by having the batteries manufactured in the US. The consumer batteries are manufactured in China; don't know if Tesla's variants are made in Japan or China. Can't imagine the shipping and import savings would offset the labor expense.
     
  16. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    A press release from 2010:
    Panasonic Presents First Electric Vehicle Battery to Tesla | Press Releases | Tesla Motors

    They are made in Japan in an automated plant. (The weakened Yen definitely helped the Q1 results.) Then they're shipped to CA and assembled into batteries in an automated process, which is good because it means that they can scaled battery manufacturing pretty easily and the cost is based more on energy and supply chain efficiency than manpower costs. As CapO has so ably explained, it's better to say that Tesla uses "cell cores" rather than "cells".
     
  17. JohnQ

    JohnQ Active Member

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    Thanks, that's helpful.
     
  18. Ron Scarboro

    Ron Scarboro New Member

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    Any increase in kWh is likely to come with an increase in weight unless the battery technology changes. I wonder how much range would be lost due to moving more mass. I assume a lot of analysis went into the relationship of weight, capacity and efficiency.
     
  19. Larry Chanin

    Larry Chanin Model S Perf Sig 1055

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    Yes, this is quite true.

    Switching to the current Panasonic battery technology we see a 22% improvement in kWh offset by a 17.6% increase in cell weight, or an extra 160 pounds. So the trade-offs of carrying that extra weight, all the time, might make it unfeasible to introduce a 103 kWh battery for purchase until the battery chemisty permitted a lighter battery.

    However, for a battery swapping operation, where the battery pack is rented, having a 22% larger battery makes sense for those few occasions where the extra range is really needed. Then when the client is done the battery is returned to Tesla and his/her Model S returns to its former lighter weight.

    Larry
     
  20. dsm363

    dsm363 Roadster + Sig Model S

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    How about they just bump the specs up a bit to 90kWh or keep it at 85kWh and use slightly less cells? Don't know if that would cost Tesla less to make as I'd imagine the newer generation of cells cost more than the previous generation. They could do things like this from time to time (like Apple does with the new iPhone having slightly more talk time..etc) but not sure if everyone is ready to have their 85kWh pack not be the top after less than a year. Tesla has shown they don't wait to update their products with the P85+ though.
     

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