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Battery/Charging System - Model-Year Upgrades?

Discussion in 'Roadster: Technical' started by dan_hudson, Apr 14, 2009.

  1. dan_hudson

    dan_hudson New Member

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    Please excuse the potentially redundant post - poked around the archive and couldn't find an appropriate discussion/answer...

    Can anyone share insight on provisions Tesla has made regarding dramatic technology changes in battery infrastructure?

    Pretty clear a lot of $$$ is being thrown at battery technologies. Just how modular is the Tesla approach? Not just the batteries, but charging, regulation, etc. Even the form-factor in the car itself. Room to move things around? Deal with different thermal characteristics? No doubt a dramatic change would be quite expensive. But you'd assume the payoff would be dramatic as well. But is it reasonably possible?

    With the new Sedan model coming down the pike, it all starts to become almost reachable, sticker price-wise. But how to overcome fear of living on the leading edge. If there was only a "changing technologies" tab at Tesla.com!

    Thanks --Dan
     
  2. graham

    graham Active Member

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    Well, the short answer is that whatever battery technology is out there, if it exists in a 18650 form factor it should theoretically be swappable into any Tesla battery pack. Depending on the newer chemistry, it will most likely require a firmware change as well.

    The battery pack form factor itself is a little more difficult in the Roadster to swap for newer technologies, but should be easy to swap/replace in the Smart and the Model S.

    I am expecting to some day be able to swap out the Roadster battery pack with either a lighter one, or a greater capacity one (or both). I am hoping it will be just a battery cell swap and a firmware update - but I can imagine it may require more than that.
     
  3. dsm363

    dsm363 Roadster + Sig Model S

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    #3 dsm363, Oct 14, 2010
    Last edited: Oct 14, 2010
    Just curious but why does everyone think Tesla hasn't upgraded to the higher capacity 18650 cells with the Roadster 2.5 for more range? Is the cost difference that much from what they're using now to the next step up? If I understand correctly, there are now two steps up in energy density for these cells that Tesla could go with. Cost is probably the main reason but would have thought for the 2.5 advertising a 300 mile range or something would help sell cars.

    Dave
     
  4. TEG

    TEG TMC Moderator

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    Costs may in part be due to large contacts. Say for instance you agree to buy 5 million 2400mah cells in one bulk purchase, I bet you get a much better price than buying 200K in one batch, 200K in another batch, then switching to a 200K batch of next gen cells. In other words, the auto business tends to factor in long lead times to switch components because you want to make long term contracts for large volumes.
     
  5. Alan

    Alan Member

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    Even if its not bulk purchasing then sticking with the same capacity makes some sense - they get cheaper as newer, higher capacity versions come out.

    This increases profit margins now and will help replacement packs look affordable.

    In the longer term, the gap between the current capacity cells and the next ones up price wise may be small enough so that it becomes sensible to make a lighter pack with the same capacity and less cells internally.
     
  6. dsm363

    dsm363 Roadster + Sig Model S

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    Maybe they could even offer a higher capacity batter pack as an option (like the Model S).
     
  7. tomsax

    tomsax Member

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    It may also require an entire new round of testing to optimize charge and discharge profiles to ensure safety margins and maximum battery life.
     
  8. vfx

    vfx Well-Known Member

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    #8 vfx, Oct 15, 2010
    Last edited: Oct 17, 2010
    There is the battery-balance issue to contend with.

    At some point they will make the switch. But they will have 1,500 cars out there that have to use the old cells (10 million of them) to keep the battery balanced. I believe legally they have to keep a 7 year supply of auto parts in stock.

    Of course they many wish to offer and later require a "battery retrofit" with all that it entails.
     
  9. Eberhard

    Eberhard #421 Model S #S32

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    That what i want too. The standard 18650 have 2200mAh, the new for model S should have 3100mAh coming from a deal with Panasonic published early this year by tesla. The newest cell from Panasonic have even 3400mAh (4000mAh but higher weight) with the same weight. Getting an extra 40-50% increase in range would be wonderful. I am about to order a new roadster. i made a testdrive with the sport which was really great. but i would prefere a roadster with higher capacity then the sport for the same price.
    Its also the reason whyTtesla is happy with the 18650. highest energy density being possible.

    Eberhard
     
  10. vfx

    vfx Well-Known Member

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    Yes, further range will impress more of the general public to what an EV can do. Faster acceleration will only wow the gearheads who are already gob-smacked.

    Elon is getting his 3rd Roadster as #1 is probably museum-bound.

    Do we owners have to worry that others that are able to get new cars are doing so because they have to?
     
  11. Eberhard

    Eberhard #421 Model S #S32

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    But what i dont understand, is why is Tesla ristricting themselves by only one-phase charging. While recuperating from the AC-engine, they use 3-phase or am i Wrong?
    I have 400V/32A that would recharge the batterie within 2.5h with no hazzle instead of unbalanced charingin with one-phase on 400V/63A fpr 3,5h ?
     
  12. doug

    doug Administrator / Head Moderator

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    That's basically right. We've talked about a desire for 3-phase charging in a few places on this forum already. Not sure how you calculated those charging rates, but that unbalanced single phase turns out to be 230 Volts (one phase to neutral).
     
  13. TEG

    TEG TMC Moderator

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  14. Eberhard

    Eberhard #421 Model S #S32

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    Thats correct. on three phases you can charge three times faster - 400V/32A means simple 3x6.6kW = 20kW or same as 230V 96A
     
  15. richkae

    richkae VIN587

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    I'm hoping that after the Model S launches there will be a replacement Roadster pack with the same energy and power but 30-50% lighter made with new cells.
    I also think that Tesla is paying far less for those 2200 cells now than they did a couple of years ago and that is dramatically improving the margins on the cars today.

    There's a little bit of engineering and testing to change, and its probably blocked by all the Model S work.
    If Tesla were more focused on the Roadster, I think that every model year or two they would be trumpeting how the new model had a lighter battery pack that improves all the performance capabilities of the car. Hopefully once the Model S bottleneck is gone, a huge improvement will be available - 5 years worth of improvement in 18650s!
     
  16. Eberhard

    Eberhard #421 Model S #S32

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    As the Model S is taking profit from all developments done for the roadster as being a proff of concept. The Roadster will later get most of the improvements, done for the Model S including 3 phase charging and higher batterie capacity (up to 100 kWh)
     
  17. TEG

    TEG TMC Moderator

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    I assume you are talking about some future replacement for the current Roadster, right?
    For instance, something that might be called "Roadster 3.0" or somesuch.

    I wouldn't assume that existing Roadsters will get such upgrades. Although, one can always hope.
     
  18. SByer

    SByer '08 #383

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    Oooh, I sure wouldn't count on it. It's only the ongoing form factor and that the upgrades so far have been component-level and not design-level. I don't see that being the case with an S-platform based sports car. I just hope that if/when I'm ready to replace the Roadster that the follow on model really isn't as big as a 911, which is just too darned big, IMO.
     
  19. Eberhard

    Eberhard #421 Model S #S32

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    the new cells for model S will have 3100mA insteat of the current 2200mA but same size 18650 and same weight. easy to replace when the whole batteriepack needs to be replaced
     

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