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EV Terminology, Measurements, and

Discussion in 'Electric Vehicles' started by vfx, Aug 27, 2012.

  1. vfx

    vfx Well-Known Member

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    To our resident scientists.

    It's clear that the new Electric cars need some new terminology, measurement methodologies, and displaying of available information.

    This thread is a gathering place for all those "we need to come up with a term for X because this is all new in an EV" and the "they should have done this cause it's an EV" and "Why didn't they show us X because it's an EV and all that data is there and we want to compare"

    This is how an EV does not fit into the "standardized tests" developed for ICEs over the last century.

    Examples:

    Dan Neil
    CapitalistOppressor
    loganss
     
  2. vfx

    vfx Well-Known Member

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    From JB
     
  3. vfx

    vfx Well-Known Member

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    There are so many ways to look at it. There really could be several MPGe ratings:

    -Total energy required, or "well to wheel" efficiency (includes refining/shipping on the gasoline side, and the electrical analog: mining/generation/transmission & charging losses). This number alone can vary drastically...are you using solar power generated atop your roof, or a dirty coal plant?

    -Cost-based: Cost for x miles of electricity vs. cost for x miles of gasoline.

    -Vehicular efficiency (thermodynamics-based): This is the miles per kWh of electricity consumed from the battery vs. miles per kWh of gasoline energy equivalent.


    Todd
    There are many others...they can all convert into "MPG-like" values but they all tell a story of a particular aspect of the thermodynamics that compare the efficiency of one vehicle vs. another. The EPA uses wall-to-wheel (pump-to-tank) based MPGe. But if someone asks how efficient the Model S's drivetrain is, I'll tell them that the entire 300 mile battery pack has the equivalent of 2.5 gallons of gasoline energy equivalent.
     
  4. TEG

    TEG TMC Moderator

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    #4 TEG, Sep 6, 2012
    Last edited: Sep 6, 2012
    The standard "0-60" benchmark times so often published to compare performance are frequently hard to achieve with many ICE cars.
    They may get the professional "pinch hitter" driver who knows how to "dump the clutch" just so at 5K+ RPMs to extract that best 0-60 time that goes into the report. But for EVs, the performance is so predictable, consistent and easy to achieve. Teslas have 0-60 times that are "world class" but it doesn't emphasize how easy they are to achieve. Plus you don't have the drama of exhaust noise, and such. Sometimes I wish the published 0-60 times were some sort of average of many runs (not just the best time), and not to be done just by some professional performance extraction specialist. It would be nice if there was some way to better emphasize that a particular "0-60" in an EV is really a "better" 0-60 than the same value published for an ICE vehicle.

    By the way, even though the LEAF acceleration is only modest, I find I can get away with full-pedal starts almost all the time without anyone getting up in arms due to lack or control or excessive noise. I find the quiet/smooth/controlled/predictable nature of the EV acceleration makes it so much more accessible and usable...
     
  5. vfx

    vfx Well-Known Member

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    And a full accounting of Launch control. The procedure of switches and how long it takes to initiate the sequence to ready. And disclosure that the driver is not even doing the accelerating.

    Model S: 0 secs

    Bugatti: 6 seconds
     
  6. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Does that mean you don't get a ticket?
     

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