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$12K Battery replacement option

Discussion in 'Roadster' started by malcolm, Jan 17, 2009.

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  1. TEG

    TEG TMC Moderator

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    Well, I imagine that many Tesla execs are driving Roadsters and so they may want to do some improvements for their own cars, not just the small(ish) number of "legacy customers" that would be interested too.
     
  2. Eberhard

    Eberhard #421 Model S #S32

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    the changes to be made are most software or even simpler, just change some parameters. it is uncommen, that tesla would not do tests with modifyed batterypack to get real results from everydays driving. how will tesla justify the hugh premium on the final edition without something very special like new lithium chemistry.
     
  3. richkae

    richkae VIN587

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    #103 richkae, Jul 16, 2011
    Last edited: Jul 16, 2011
    I'm suggesting they use exactly the same cells that they happen to be using for the long range Model S and Model X when they do this.
    So then, as Eberhard says, its just a trivial software settings change.
    It might be a little bit of work to have partially empty bricks ( to use fewer cells ), but I think that is trivial too.

    As to the why...
    Tesla needs to stay interested in the flagship status of the Roadster, even though it is a discontinued limited market product. Tesla will always have the oldest EVs on the road - and they will all be Roadsters - because of their 2+ year head start on Nissan.
    ( Yes I am ignoring Toyota and the abandoned RAV4 EV )
    People walking into the Tesla store and asking about the service life of the Model S, should be pointed to the 5 and 6 and 7 year old Roadsters. If Tesla themselves doesn't do it, it will be up to us to stir media interest.
     
  4. Eberhard

    Eberhard #421 Model S #S32

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    If I would not have the problem with soldering 6831 cells - i would go straight to Panasonic and purchase those cells as replacement for my current ones.
     
  5. daniel

    daniel Active Member

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    What you're leaving out of the equation is the question of whether or not a new battery will actually be needed. Buying the replacement option locks you into the purchase of a specific battery. (Any suggestion that you may be able to exchange the option for something different is speculation.)

    True! OTOH, some folks (me included) regard the battery as a wear item, and though I don't want to waste it, I also don't want to reduce the usefulness of it by limiting myself on what I can do with it. I would not buy any EV if I could not afford the eventual battery replacement.

    Yes, but if you have a grid-tied PV system and you are feeding excess energy back to the grid, using less energy in your car means selling more to the grid and contributing (in a very small way) to the nation's energy independence.

    OTOH, taking that to the extreme, you'd never drive at all. Fortunately, the Roadster (and EVs in general) uses about half as much energy per mile as a Prius.

    I think I would not. I bought the car because it's electric, not because it's fast, and 245 miles is double what I expect to ever need in a roadster. I have no interest in a quicker car or longer range in this kind of car. When/if my range drops below around 125 or maybe 150 miles I'll replace the battery with the same technology if it's available at a lower price than the hypothetical improved technology.

    For longer trips than 200 miles, or even longer than 150 miles, I want a more comfortable car. If the Model S offered a 400-mile battery pack it would do me for my road trips for hiking in Canada and I'd trade in my Prius for it.

    I'm not willing to accept the inconvenience of a 3-hour charge in the middle of a 7-hour drive (making it a 10-hour trip, which I'd have to split into two days) and where I go, fast charging is not going to be available for a very long time, so it would be more like a 6-hour charge in an RV park; again an overnight, involving leaving the car plugged in and finding a hotel away from the car. Not an acceptable compromise compared to driving the Prius.

    The Roadster, exactly as it is, is the ideal daily car for me.
     
  6. dsm363

    dsm363 Roadster + Sig Model S

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    I'm hoping just switching out the exact number of cells with higher capacity cells and building a new pack isn't hard for Tesla. If that doesn't require anything other then some testing, it should be possible.
     
  7. bonnie

    bonnie Oil is for sissies.

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    We're all making a bet here. I know that if I had been one of the early adopters, I would not have taken the battery replacement option. Tesla was too new of a company, too much risk they wouldn't be around to honor the contract. That possibility always exists, but it's certainly less of a risk now than it was for many of you in 2008. I can't justify fully either way - but I took the bet and have no regrets.
     
  8. Slackjaw

    Slackjaw Member

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    #109 Slackjaw, Jul 18, 2011
    Last edited: Jul 18, 2011
    Great, thanks for that :biggrin: ... We drive an electric car, powered by renewable carbon-free energy (in NJ: Green Mountain Energy Company). I'm not going to feel too guilty.

    At risk of dragging it all out way too far, I think you missed my point. It's not really about the money at all. It's like this: Let's say I'm on holiday and I find a really neat coffee mug, like those ones with the Star Trek crew on and they teleport away when you add hot coffee. It used to be that I'd buy one of these mugs, and then a week or two later I'd be drinking out of it every day (call this state A) and then I'd knock if off my desk and it would break and that would be that, no more teleporting Star Trek crew.

    Then, after a few experiences like that I would be more careful, and I'd maybe put the Star Trek mug in a cabinet and not use it so much for fear of breaking it (call this state B).

    But now, what I do if I can is buy two of them. One is the backup. The primary is for daily use and I get maximum enojyment out of it, knowing that in the event of a terrible accident I'll always have the backup. And this is absolutely not the same as insurance, because I don't care if someone offers to give me $5 when I break my coffee mug. I don't take unnecessary risks with the primary coffee mug, I just use it happily without that fear of loss hanging over my head (call this state C).

    So, the disclaimers and the "no more roadsters" aspect precludes state A, and we're talking in my case about state B, or state C. Feel free to recast this as capitalist propaganda, but I always thought TMC was an anarcho-syndicalist commune...

    :wink: :biggrin:
     
  9. S-2000 Roadster

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    Be prepared to alter the firmware in the electronics in two places: Within each sheet, and in the PEM. As far as I understand, there is intelligence in each of the 11 battery sheets within the ESS. That system could get totally confused if you altered the battery chemistry by a complete swap. Also be prepared to upgrade specific semiconductor parts in the ESS and PEM if the voltage or current from those new Panasonic cells exceed the design limits of the original.

    Rich, you make some good points about why Telsa Motors might already be motivated. But if they don't improve the battery, we have more options than just sicking the media on them. There's also the possibility of engineering a third-party upgrade. It wouldn't be cheap or easy to pull off, because we're talking about very advanced electronics here, but I'm already imagining taking measurements of the removable sheets in the ESS and thinking about what it would take to make the battery serviceable at that level.
     
  10. hcsharp

    hcsharp Active Member

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    That won't be necessary (updating the sheet/brick circuit firmware). The voltage is the same on any Li-ion cell whether hi-capacity or otherwise. The current (amp) capacity and overall energy density is greater with the newer cells but that's mostly irrelevant to the firmware because the amperage draw through each cell is controlled by the PEM, not by the cell itself. I wonder if there is any hard data yet on life expectancy of the new nano-tech hi-capacity Li-ion cells. If I had to guess, I'd bet they last longer than the current-generation cells if you treat them the same way.
     
  11. Eberhard

    Eberhard #421 Model S #S32

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    The cells capacity is changing dramatically through the life-cycle. the software has to be able to adapt to this. only if max. voltage while charging and lowest voltage while discharging has to to be change because of different chemistry only those parameters hast to be changed. Only a software/firmware update necessary. You get always updates when you car is maintained.
     
  12. S-2000 Roadster

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    There's still the possibility that the increased current capacity could exceed the ratings of the existing electronics, assuming you change only the cells. In addition, since the system can measure the current, the firmware might not react as you want it to when faced with current levels that exceed the present system's capabilities.

    By all means, though, if you want to solder some new battery chemistry into your ESS without changing anything else, then go for it. Just be sure to report back here what the results were. At least you have the VehicleLogs and various parsers available to see what happens.
     
  13. smorgasbord

    smorgasbord Active Member

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    How cheap is Tesla’s battery?

    From Seeking Alpha:


    I think the author is probably off by a factor of two or three in his dollar amounts, but the percentage decline is outlined by Tesla in the investor presentation he references. It shows the Roadster's battery cost (in $/kWh) dropping by 30% by the time the Roadster Sport was announced, and is expected to be down 58% for the Model S. That means the Model S's battery will cost Tesla less than half what the original Roadster's battery cost, in dollars per kiloWatt-hours. That kind of slope is pretty darn impressive.

    If the Roadster's battery was $30K when it was first produced in volume, a replacement will be $12.6K next year, if you believe Tesla's presentation. At any rate, I think it supplies a rationale for not getting the battery warranty if you intend to keep the Roadster for a while. If you intend to sell it, however, having the warranty may help alleviate concerns from potential buyers.
     
  14. TEG

    TEG TMC Moderator

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    I think Tesla went straight from 2008 Roadsters to 2010 Roadsters, so it seems to be a goof to mention 2009 Roadsters in that article.
     
  15. tennis_trs

    tennis_trs 2010 2.0 Roadster Sport

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    Yeah, that gets screwed up all the time in articles.
     
  16. richkae

    richkae VIN587

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    You can get quotes on Alibaba for Chinese 2200mah 18650 cells for between $1 and $3 each - depending on quantity ( yes I know there is probably a quality difference between those and Panasonic )
    1 kWhr of 18650s in the Roadster is about 128 cells. $200 to $250 dollars is somewhere between $1.56 and $2 per cell.
    It is totally reasonable to think that Tesla can get them for that or better - surely Tesla can get the best possible volume discount.
     
  17. smorgasbord

    smorgasbord Active Member

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    I came across this article in Technology Review. It has this graphic for "The Price of Batteries":

    2010 Estimate: Low: $600/kWh to High: $1105/kWh
    2015 Estimate: Low: <$500 to High: $600/kWh
    2020 Estimate: Low: $225/kWh to High: $500/kWh
     
  18. richkae

    richkae VIN587

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  19. S-2000 Roadster

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    Those prices don't count the liquid cooling or the circuit boards that manage individual sections of the pack. If you want your EV battery to die as quickly as your laptop then just connect a bunch of cells together, but if you want them to last as long as the Tesla technology then it takes a lot more than cells. The cells could be free and the ESS would still be a fairly pricey piece of technology until it is manufactured in vast quantities.
     

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