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Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable)

Discussion in 'Model S: Battery & Charging' started by wk057, Feb 2, 2016.

  1. vgrinshpun

    vgrinshpun Supporting Member

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    Data from Tesla EPA certification application dated 12/02/2014 indicate that:
    • usable capacity of 85 kWh battery based on C/3 discharge rate is 83 kWh
    • usable capacity of 85 kWh battery based on discharge rate to support EPA City Cycle Testing is 80.640 kWh
    • usable capacity of 85 kWh battery based on discharge rate to support EPA Highway Cycle Testing is 80.731 kWh
    Summary of Data
    upload_2019-4-20_20-45-56.png


    Excerpt from the Tesla EPA Certification Application dated 12/02/2014

    upload_2019-4-20_20-40-49.png

    Link

    https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=34511&flag=1
     
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  2. Cloxxki

    Cloxxki Active Member

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    VW gets a lot of legal problems and public complaints over making their cars pass tests by adjusting settings when in a test.

    Tesla labels a product 85 when really it should be 80 and they know it. And would be 77 at other brands. Nerds object, the crowd doesn't care.

    Anyone want to buy a liter of joghurt off me? The inner container size is 100x100x94 mm.
     
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  3. vgrinshpun

    vgrinshpun Supporting Member

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    Problem with math:
    80.73 kWh usable + 4 kWh buffer = 84.73 kWh (EPA Highway Cycle discharge)
    Rounds to 85 kWh

    83 kWh usable + 4 kWh buffer = 87 kWh (C/3 discharge)

    For other brands - check Jaguar or Audi.
     
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  4. No2DinosaurFuel

    No2DinosaurFuel Active Member

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    Note test data taken from Tesla report. So we cant completely trust Tesla's number.
     
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  5. vgrinshpun

    vgrinshpun Supporting Member

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  6. Reciprocity

    Reciprocity Active Member

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    Are you'all still debating this because the competition is still trying to catch up to the 85's like 5 years later?
     
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  7. Cloxxki

    Cloxxki Active Member

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    Most of the competition is specifying batteries by conservative usable capacity, not rounded up theoretical total.
    As a design the 85 seems really up there still, better than the later 90, unfortunately.
     
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  8. vgrinshpun

    vgrinshpun Supporting Member

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    Not true for Jaguar I-pace
    Not true for Audi e-tron
     
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  9. Cloxxki

    Cloxxki Active Member

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    I regard both as 50/50 compliance cars more than serious best effort BEVs to make loads of.
    In the case of Audi, they of course take a liberal reserve to get from total to usable.

    And I said "most", so better address that part of my argument rather than finding two. You could also deflect by going into what "competition constitutes. I should have stated: progressive BEV makers now often state conservative usable capacity rather than total.
     
  10. Electroman

    Electroman Well-Known Member

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    Not true for Nissan Leaf 24 kWh battery either
     
  11. vgrinshpun

    vgrinshpun Supporting Member

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    Let me know which cars are included in “most”. Kindly include data backing this up.
     
  12. Cloxxki

    Cloxxki Active Member

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    I can't be bothered, you didn't show good faith there. There are better ways to reflect battery capacity and Tesla stopped reflecting it in kWh, went to distance units.
     
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  13. vgrinshpun

    vgrinshpun Supporting Member

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    Not true for BMW i3
     
  14. vgrinshpun

    vgrinshpun Supporting Member

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    Thank you. Your claim was baseless.
    We can’t trust you.
     
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  15. JRP3

    JRP3 Hyperactive Member

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    Correct, he makes baseless claims, then complains when people call him out.
     
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  16. wk057

    wk057 Senior Tinkerer

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    Wow. Didn't expect to see this thread resurrected.

    Been sitting on this, mostly, but since the last time I posted anything relevant here, a Tesla insider leaked a TON of data to me about the entire fleet of Tesla vehicles. That data quite clearly shows that no 85 was ever 85, no 90 was ever 90. In fact, the vast majority of 90 packs have even degraded to be below the capacity of the vast majority of 85 packs at the time that data was given to me. This is their own internal data. 60, 70, 75, and 100s get a pass, as most of those meet spec. 85 and 90 folks got mislead, and they should be labeled 80 and 85 respectively. Since Tesla charges.. what, $3k to upgrade from a 70-75? ... I feel like we should all get $3k in credit or something. Not going to happen, but it is what it is.

    Also since that time I've run capacity tests on loads of 85-type modules... and, you guessed it, not even the best come out to 85 kWh total capacity.

    Next, I actually spoke with an ex-Tesla engineer who actually worked on the BMS software early on. He explained that the 4 kWh "buffer" doesn't mean what we think it means. It was actually a kludge built in to smooth the range calculation, and to make sure you actually could hit zero miles consistently without getting stranded. On average, the actual capacity "buffer" is 2 kWh, so the code was written so that a 4 kWh window was used and scaled along with the SoC as the car discharged, adjusted and calibrated as possible based on other measurements. This was to ensure that the range calculation would never adjust abruptly, and should never (rarely) run out of capacity while rated miles were > 0. TL;DR: The actual capacity left on the table by the value of the "buffer" is targeted by the BMS to be half that much.

    Finally, in the past 2 years since my last substance post in this thread, I've almost completely reverse engineered the Tesla BMS software and hardware. Guess what's in there? Oh, right the factory "new" profiles for every battery type. More interestingly is that the other values (like those actually reported by the BMS) are directly derived from the initial factory capacity number. Anyone want to take a stab at what the new-from-the-factory values are for the "85"? Spoiler: Not 85. If you guessed 80, you win. (And for those playing along at home, the remaining initial values: 60 for the 60, 70 for the 70, 75 for the 75, 85 for the 90, and 100 for the 100.... one of these things is not like the other...). (Note: My reverse engineering also confirms what the engineer told me above.)

    Let's stop beating this dead horse and get over it. Tesla lies, and they lied about the 85 capacity. Still love the products, hate the company.

    [​IMG]
     
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  17. vgrinshpun

    vgrinshpun Supporting Member

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    #1117 vgrinshpun, Apr 21, 2019
    Last edited: Apr 21, 2019
    Do I understand this correctly, that based on the results of your almost completely reverse engineered BMS software and hardware, consistent with the information provided by a former BMS software engineer, usable capacity of:

    • 60 kWh pack is 60kWh
    • 70 kWh pack is 70kWh
    • 75 kWh pack is 75kWh
    • 85 kWh pack is 80kWh
    • 90 kWh pack is 85kWh
    • 100 kWh pack is 100kWh

      right?
    [/QUOTE]
     
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  18. wk057

    wk057 Senior Tinkerer

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    #1118 wk057, Apr 21, 2019
    Last edited: Apr 21, 2019
    Don't add words to my writing. I never said usable. I was very clear that I was referring to the total capacity of the actual batteries.

    Edit: In case it wasn't clear enough, usable capacity is always going to be less than the total capacity. The weirdness with the buffer kludge makes this more complicated, but not by much. The real new usable capacity is going to be the factory new total capacity, minus 2 kWh, +/- 1 kWh.
     
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  19. vgrinshpun

    vgrinshpun Supporting Member

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    Thank you for clarifying this. So what is usable capacity of the brand new 60, 65, 70, 85, 90 and 100kWh packs according to your research?
     
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  20. whitex

    whitex Active Member

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    Fyi, in case you didn't catch it, they discounted the 70-75 upgrade for software locked Model S to $500 back in 2017. They also discounted 60-75 MS unlock at that time to $2,000 (I took advantage of that one, so I know it wasn't just a rumor).

    Thanks for the additional information from the BMS software btw.
     
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