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EPA rates Model S at 89MPGe with 85 kWh pack

Discussion in 'Model S: Battery & Charging' started by Discoducky, Jun 20, 2012.

  1. AndyM

    AndyM Member

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    Yep, they do, leftmost column:
    Screen Shot 2012-06-20 at 19.34.50 .png
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    Thanks. I meant the electricy cost ($0.10/kWh for example).

    Ah, I see it on the sticker now. Looks like 12 cents/kWh.
     
  3. AndyM

    AndyM Member

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    Ooops! Misunderstood, sorry.
     
  4. ddruz

    ddruz Member

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    It appears as if this extrapolation assumes equal weight for the 40 kwh car as the 85 kwh car. However, the 40 kwh car should be significantly lighter and may therefore receive an EPA rating significantly higher than 120 miles per charge. Of the three Model S cars its lighter weight and inability to accelerate as quickly may also lead it to receive the highest MPGe of the three. It will be very interesting to see the real numbers.
     
  5. Dave EV

    Dave EV Active Member

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    The lighter weight of the 40 kWh S might help with city economy, but I wouldn't expect to see a significant difference in highway economy. Limited power certainly won't come into play at all in the EPA tests. Only a tiny fraction of peak power is used for the tests.
     
  6. ddruz

    ddruz Member

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    All other things being equal a lighter car should get better mileage city or highway, should it not? Wind resistance is similar regardless of weight and while it becomes a dominant factor at higher speeds moving less weight should still require less energy.
     
  7. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN 65513, Model 3: VIN 1913

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    Wait, wasn't there talk of there being added dead weight to the 40 pack to make the car weigh the same as an 85 pack for uniformity w.r.t. crash testing?
     
  8. daniel

    daniel Active Member

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    Comparing to an ICE car, the consumer wants the comparison of pump to wheels against wall to wheels. You pay for gas at the pump; you pay for electricity at the wall. Another way of thinking of it is that charging losses are within the car, therefore are part of the car's consumption. From a cost-to-operate standpoint, this makes sense. I've always used kWh at the wall when stating miles per kWh, as it does not require an efficiency conversion factor when going from that to cost per mile for "fuel."
     
  9. W.Petefish

    W.Petefish Active Member

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    Am I missing something here, or do those numbers seem off? Those numbers, should be reversed at the very least, if you factor in regen.
     
  10. AnOutsider

    AnOutsider S532 # XS27

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  11. Dave EV

    Dave EV Active Member

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    For everyone stressing about the "horrible" 89 MPGe of the Model S - how about a comparison to the Fisker Karma?

    You know - the car similar in exterior dimensions to the Model S, yet much smaller inside - which only musters 52 MPGe and 64 kWh / 100 miles.

    All of a sudden 89 MPGe and 38 kWh / 100 miles looks really good when you're comparing something closer to apples to apples...
     
  12. Citizen-T

    Citizen-T Active Member

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    For everyone stressing about the "horrible" 89 MPGe of the Model S - how about you charge at night (if you can get variable rates) then you'll magically have a 180 MPGe car.
     
  13. drbradfo

    drbradfo Member

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  14. Tommy

    Tommy Member

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    I would be interested to know at what rate the EPA (or contracted lab) charged the Model S at; as has been shown with the Roadster, there is an ideal charge rate that minimizes the charging losses. It probably won't move the needle much if the EPA charged at the most inefficient rate (110v), however if they did, then I can take comfort knowing some improvement in the mpg-e can be done simply by charging at 240v instead.
     
  15. BYT_P1837

    BYT_P1837 Member

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    Comparing a Model S to the Fisker Karma is more like comparing an apple to a crab apple... ;)
     
  16. Citizen-T

    Citizen-T Active Member

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    Elon actually did say during the last conference call that Tesla was going to try to get that number raised by making some tweaks to the charger or connector or something like that. I don't remember exactly what.
     
  17. SoCalGuy

    SoCalGuy Active Member

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    I don't quite understand the math here.

    If it's true that it gets 265 miles with an 85 kwh pack, then that translates into 265/85 = 3.11 miles per kwh. 1 gallon of gas has 33.7 kwh of energy, so the MPGe should be 33.7 x 3.11 = 105 MPGe, no?

    That's how the Fisker's EPA numbers shake out... 32 mile range on 20 kwh, 32/20 = 1.6 miles per kwh. 1 gallon of gas has 33.7, so MPGe for Fisker is 33.7 x 1.6 = 54 MPGe (close to its 'official' 52MPGe rating).

    What am I missing?
     
  18. mnx

    mnx 2013 P85

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    Someone already explained in this thread, that the MPGe takes into account charging inefficiencies, while the driving range of the car is independent of that.



     
  19. Dave EV

    Dave EV Active Member

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    Typically the manufacturer runs the numbers them selves and submits them to the EPA. The EPA lab only verifies a small fraction of the vehicles on the market each year. Not sure if the Model S was actually tested by the EPA or not. But given the scenario you can pretty much guarantee that Tesla will have chosen the most efficient charging rate to present the Model S in the best possible light.
     
  20. cinergi

    cinergi Active Member

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    Yes during annual shareholders call he was saying they might be able to get more than 89 MPGe if they could improve charging efficiency.
     

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