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ESS software questions …

Discussion in 'Roadster: Technical' started by PV4EV, Oct 26, 2011.

  1. PV4EV

    PV4EV Member

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    This is a long time lurker's first post … be gentle! I have a Roadster 2.5 due to arrive in a few weeks time, and I'm counting the days. Below are a few questions that I'm curious about to which I cant find answers from older threads, although I can see the subject area has been discussed before.


    One thing offered to me at purchase time was the $12k / £9k payment for whatever future ESS replacement solution Tesla Inc might have, if/when the existing ESS keels over, hopefully at well over 100,000 miles time. They hint that a replacement ESS may be something quite different from the existing unit.

    Meanwhile, I'm developing a consumer electronic device subject to patent that uses high capacity 18650's, and energy storage is something I'm very interested in generally. I am aware of rapid developments in energy storage research including things like Lithium Air based cells, Graphene based ultra-caps, and other emerging possibilities, all of which hold out the promise of 500 to 1000+ miles 'range' in 5-10 years time …


    So, what is possible with an ESS upgrade right now ? …

    The ESS uses #6831 x 18650 cells from Panasonic rated at a nominal 2.1Ah, and was designed / developed / refined between 2005-2006, or thereabouts.

    Since 2010 Panasonic have been able to supply 18650s rated at approx 3.0Ah.

    According to their datasheets, the two cells have identical thermal / electrical characteristics and current cutouts for the same load conditions with the only difference being that the energy capacity is +40% and the charging profile is different to the original cells, and the car would take longer to charge. If the cars performance / power demands remain the same spec, then surely all the thermal controls and SOC monitoring will be, broadly speaking, the same.

    If Tesla offered upgrades to the ESS with newer cells it would allow them to claim a headline grabbing genuine 300+ mile ability for the Roadster … or even 400miles if the forthcoming 4Ah cells are use.

    If enhancements like this were announced to support the 'older car', combined with all the Model S PR and its 320mile range, then surely the range anxiety arguments from the ICE industry all start to look a bit weak ? ( And both my last ICE cars could not average more than about 280 miles on a tank full… with only 140miles if I hammered them everywhere!)


    So :-

    (1) Does anyone know if the existing Roadster software has the hidden-facility to initialize and balance an entire ESS fitted-out with a set of new higher capacity 18650's ?

    (2) Do you think that the existing software (or via an upgrade) allows for altering the charge profile for slightly different cells?

    (3) Do you think that as Roadsters fall out of warranty in the years ahead, that a 3rd party support network will form offering a reverse engineered ESS cell upgrade ?! (and hopefully not as a result of Tesla going belly up - I've just bought shares too!)


    Can anyone offer some insight on the above ?!


     
  2. qwk

    qwk Model S P2681

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    I'm very interested in this idea also. Unfortunately, unless you are an engineer or higher up at Tesla, you won't know a definite answer to these questions. My speculation is that they have messed around with higher capacity cells in certain roadsters(Elon's for example).

    Fitting higher mah cells in the roadster pack is probably not that difficult. The biggest headache would be the software for the PEM/BMS. I'm quite certain that as soon as enough roadsters come out of warranty, people will tinker and find out just how difficult this proposition is.
     
  3. fraccy

    fraccy Member

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    The only insight I can offer is, I've had my roadster about 6 weeks, and spent the 2 months waiting for it fussing over every aspect of the possibilities of battery improvements and what-if upgrade scenarios.

    Since getting the car, I've not given any of it a second thought, and the only area I feel let down in is the lack of 3-phase charging. The car might just be fine as it is. Just my two cents.
     
  4. TEG

    TEG TMC Moderator

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    Keep in mind that with 6831 of them, even a "small job" for an individual cell becomes a large job for a whole pack.
    Also, how are they packed in the sheets? Can an "amateur" put cells in there by hand, or would you need some sort of custom machine / welding / glue / ?
    Basically, I wouldn't assume that it is an easy job. It might not be.
     
  5. qwk

    qwk Model S P2681

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    Yes, certainly very time consuming, but not that difficult. The cells are glued/soldered in. I had a link to diagrams/pics of the sheets saved on my old computer.
     
  6. Lloyd

    Lloyd Active Member

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    #6 Lloyd, Oct 26, 2011
    Last edited by a moderator: Mar 13, 2016


    Other manufacturer, but interesting nonetheless.
     
  7. PV4EV

    PV4EV Member

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    There's virtually nothing I can find in the public domain about the actual internals of the bricks and sheets within the ESS. The original 2008 Tesla patent on the ESS provides some pictorial detail on how they deal with thermal management and the individual cell mounting :-

    Mitigation of propagation of thermal runaway in a multi-cell battery pack - Tesla Motors, Inc.

    From a purely engineering prospective I would really like to dismantle an ESS and see how they solved the numerous problems getting the whole thing to work as well as it does in a production roadster.

    For anyone who hasn’t seen this, here's a 20min presentation by JB Straubel that gets pretty interesting from about 12/13 mins in, as well as showing some interesting stats when comparing various efficiency and performance increases of the Roadster to the Model S :-

    2011 Summit Video Presentation: JB Straubel | Institute for Energy Efficiency
     
  8. PV4EV

    PV4EV Member

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    I agree, especially since I have 3-phase at home and its a tad annoying not being able to use it :mad:

    I'm hoping Tesla listen to requests for 3 phase support from prospective European Model S owners, myself included.

    The USA Model S looks set for Q2 2012 release, so the Euro versions might be 12+ months behind (Q3 2013 ?) and hopefully they will come up with a workable engineering solution for Euro cars.
     
  9. Mycroft

    Mycroft Life happens

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    Even the first Roadster owner isn't getting close to the point where they would get a battery refresh so anything would be pure speculation for at least four more years.

    From a short video I saw, it looks like lithium air cells are at least 15 years out. Hopefully ultra-caps and better Li-Ion batteries will be viable much sooner.

    Like you, I'm also hoping we'll be able to retro-fit our cars with the new battery tech when prices come down. Wow, a 1,000 mile range on my Model S Signature Sport. Now THAT would be cool!
     
  10. richkae

    richkae VIN587

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    Projecting from my last 2 years of usage, I dont anticipate *needing* a new battery before mine is 10 years old.
    However if Tesla offered a new battery in 2-3 years that increased both range and performance I would be very tempted to upgrade from my completely adequate battery.
     
  11. Mycroft

    Mycroft Life happens

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    Yeah, I think that most people who pre-bought the battery refresh will postpone it as long as possible.
     
  12. qwk

    qwk Model S P2681

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    This would only make sense as you would get cash back if you wait over 7 years...

    Why get a battery replacement if the battery you have is adequate for your needs?
     
  13. PV4EV

    PV4EV Member

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    There's virtually nothing I can find in the public domain about the actual internals of the bricks and sheets within the ESS. The original 2008 Tesla patent on the ESS provides some pictorial details on how they deal with thermal management and the individual cell mounting :-

    PATENT LINK Mitigation of propagation of thermal runaway in a multi-cell battery pack - Tesla Motors, Inc.

    From a purely engineering prospective I would really like to dismantle an ESS and see how they solved the numerous problems getting the whole thing to work as well as it does in a production roadster.

    For anyone who hasn’t seen this, here's a 20min presentation by JB Straubel that gets pretty interesting from about 12/13 mins in, as well as showing some interesting stats when comparing various efficiency and performance increases of the Roadster to the Model S :-

    2011 Summit Video Presentation: JB Straubel | Institute for Energy Efficiency
     
  14. richkae

    richkae VIN587

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    I did not pre buy the Roadster battery replacement.

    I *think* I will not be motivated to replace my Roadster battery until the range is below 150 miles - unless I can replace it with something that is superior to the original battery. Even though I wont need it, I will want it.
    I know they can make a better battery, and I want the better one.
     
  15. qwk

    qwk Model S P2681

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    150 in Range mode, or standard mode?
     
  16. doug

    doug Administrator / Head Moderator

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    Nothing new, but there are some drawings here: Roadster battery (ESS)
     
  17. Picasso

    Picasso kllkkjlk

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    Depending the price Tesla offers referb packs and or new packs I'm sure an after market option will come along. A few people no longer work for Tesla who know about the pack software.

    Some roadsters now do not use the same cells. So yes software can be changed depending on cell.
     
  18. TEG

    TEG TMC Moderator

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    Intriguing!
     
  19. qwk

    qwk Model S P2681

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    Can you be more specific? Is this heresay?
     
  20. Picasso

    Picasso kllkkjlk

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    Sure I can after Xmas when my NDA runs out.
     

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