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The trouble with range guages

Discussion in 'Blog Archive' started by ThosEM, Jan 7, 2014.

  1. ThosEM

    ThosEM Space Weatherman

    Dec 13, 2013
    Annapolis, MD
    In my opinion, there is a serious problem with measuring battery state in units of distance. This practice is misleading in a very fundamental sense, because a battery is not a distance storage medium, and its actual content, energy, is used for many other purposes by an electric automobile, or any other automobile for that matter.

    My Tesla Model S is my first EV, though I have also owned a hybrid Lexus RX400h. In no case have I ever seen a distance gauge, though I have seen several trip computer displays of remaining range.

    I submit that Tesla's practice of labeling the "fuel gauge" in distance units is a major source of range anxiety because that tends to imply that this range is in some sense guaranteed and immutable. No other car manufacturer has been so rash as to do this because they all understand that range depends on many other variables and that range is NOT what is measured by a fuel gauge. Therefore all other cars display a range estimate that is independent of the fuel gauge, and tied to recent fuel consumption rates rather than to a "rated" consumption figure. The EPA rated consumption and range are useful yardsticks for comparison, but must not be represented as absolute in the same sense as energy storage.

    Tesla, you have reaped what you've sown here, confusion and dissatisfaction. One has only to review John Broder's article in the NYT to see this in action. He came to view the range reading as a misleading indicator that he did not trust, and therefore he tended to ignore it. When it dropped overnight he concluded that it was erroneous and could not be indicative of a real energy consumption by the vehicle while parked. He proceeded to drive as if he had more energy supply than he really did.

    Bottom line: I strongly urge Tesla to separate range and energy indicators and to clearly distinguish them from each other, putting a range projection in the instrument panel version of the energy app display, and energy units on the fuel gauge indicator, or at the very least enabling that option, which has a dummy switch under Units & Format settings on my Model S.

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