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Thread: EPA for 60kWh battery rated at 208mi

  1. #21
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    Are we sure this is comparing apples-to-apples here? It's always been slightly curious that there's only one EPA number for the 85kWh - you might expect the Performance and standard models to give different results (due to the 21" tyres at least - and it would be surprising if the powertrain has no effect at all).

    Maybe the '85' number is for a performance with 21" wheels while the '60' is on the 19".

    Another variable is the reserve capacity. It's reasonable to expect the top-end reserve (difference between standard charge/range charge/theoretical max charge) will scale in proportion to the pack size since the limits correspond to cell voltages, and so that wouldn't affect the relative range. On the other hand, the bottom-end reserve (2 months anti-bricking allowance after reaching 'empty') should relate to the vampire load and so should be a fixed number of kWh rather than a percentage of the pack [if I've analysed it correctly, that should actually give worse range for the 60kWh rather than better, but at least it's an example of a factor that doesn't scale - perhaps there are others].

    There's also the question of whether the reduced performance of the 60kWh means that it ends up doing less work during the EPA test. I can't find enough detail about the test cycles to say if this is an issue or not.

  2. #22
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    that was my thought exactly, 19" tires is probably part of the difference here.
    Maybe firmware updates/tuning have made all cars better too, so when the 85 gets re-tested next year it will improve too?

    Does give me more confidence that the 60 will be usable with the supercharger network, too (and that one won't have to drive 50mph to be able to make it between stops)

  3. #23
    #P-5058 mklcolvin's Avatar
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    Quote Originally Posted by Zextraterrestrial View Post
    My 85 kWhr battery is doing >310 miles rated ideal range - which I believe is going by the EPA #'s (It started at 270mi showing I think, but that was from the factory and they said they did a full charge - now it is higher )



    The 60 might be enough that I could get to a supercharger, cool
    That's good news. We might be able to actually get to 230 miles (ideal range). I haven't been able to wrap my head around the ideal/range? info from the dashboard. Which is more accurate?
    Last edited by mklcolvin; 2012-12-07 at 10:10 AM.


  4. #24
    Senior Member stopcrazypp's Avatar
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    Quote Originally Posted by NotTarts View Post
    Granted, it was pretty obvious, but someone else said the weight of the different battery packs was the same and I think this contradicts that. Let's at least hope the 40 kWh battery follows the same trend
    The weight would be the same if they went with the plan when they announced the car (which is the same amount of cells in both the 60kWh and 85kWh versions, with the 60kWh version using the less energy dense cells). I guess they decided to just use less of the same cells in the 60kWh pack. The 40kWh pack will definitely weigh less than the 85kWh because even using the lowest cells available (2200mAh) that pack will still have significantly less cells than the 85kWh version (~5000 for 40kWh vs ~7600 for 85kWh).

    The caveat here is that some of this bump in efficiency may have to do with the different tires, improvement in the charger (which Elon has said they were targeting for improvement when the 89MPG figure came out for the 85kWh version), and general software updates for the newer version.
    Because there are tons of crazy people in this world...

  5. #25
    Model S 85KW, VIN #2236
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    I was under the impression that the battery packs are the same size, weight and weight distribution in all models so that the same safety design and crash testing (and suspension design and tuning) applies to all models. If that's the case, I bet the efficiency difference is due to some combination of two things:

    1) the EPA 5-cycle testing includes a new test that attempts to measure efficiency under aggressive driving conditions (and higher speeds and lower speeds). Both 85KwH versions of the Model S accelerate faster than the 60 KwH version so it's reasonable to assume that the 85KwH S's will burn more power and therefore get a lower mpge under hard acceleration.

    2) it's possible that the 60 KwH version was tested using the new acceleration profiles released in the 4.0 software update. I think there's a good chance that smoother acceleration is more efficient.

    I bet the majority of the difference is due to #1 above.

  6. #26
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    Quote Originally Posted by arg View Post
    Maybe the '85' number is for a performance with 21" wheels while the '60' is on the 19".
    Exactly this.

    You will notice that on Tesla's new range estimator that the difference between 19" and 21" wheels is nearly exactly the same ratio as the difference in efficiency between the 60 kWh and 85 kWh cars.

    The battery pack between the 60 kWh and 85 kWh is supposed to consist of the same number of cells, so weight difference between the 2 should be minimal (no more than 100 lbs) and thus have a negligible effect on overall efficiency.

    I would expect the 40 kWh car to post nearly identical numbers to the 60 kWh car.

  7. #27
    Member Ceilidh's Avatar
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    Wow. Happy about this rating. Now if Tesla could just throw them into the production line a little early that would make a great new year...

    Cheers.
    Grey, Grey Leather, Piano Black, 60 kWh battery, Air Suspension, Standard Audio, Pano Roof, Tech package, Jump Seats, Supercharging, Twin Chargers, 19" Wheels
    P 912 / VIN 5YJSA1DG5DFP03541 Factory delivery 1/26/13

  8. #28
    Head Moderator / Administrator doug's Avatar
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    Right still some open technical questions I've been curious about and hoping Tesla will answer soon.


    • What's the difference in mass?
    • Which type can how many cells did they end up using?
    • Did they end up adding ballast mass?
    • Did the center of mass change?
    • Did the suspension setup change?
    • How is handling affected?

  9. #29
    Model S 85KW, VIN #2236
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    Ok, I sit corrected .

    Seriously, the tires make that much of a difference? Wow.

  10. #30
    Model S P2681 qwk's Avatar
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    Quote Originally Posted by doug View Post
    Right still some open technical questions I've been curious about and hoping Tesla will answer soon.


    • What's the difference in mass?
    • Which type can how many cells did they end up using?
    • Did they end up adding ballast mass?
    • Did the center of mass change?
    • Did the suspension setup change?
    • How is handling affected?
    +1

    This info interests me too. None of it is a trade secret, so why Tesla doesn't publish it is beyond me.

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