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Data over a few thousand miles

Discussion in 'Model S' started by ILLCOMM, Jul 2, 2018.

  1. ILLCOMM

    ILLCOMM Member

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    I wrote a Google Script to pull data from my MS (75D) every hour (using the API) and dump it into a Google Sheet. Of course that makes charting really simple. Finally got around to playing with the data and thought it was mildly interesting, enough so to share. Takeaways:
    1. max range does gradually decline over time, and
    2. average efficiency (in Wh/mi) is north of 300 which makes it hard to achieve rated range (which I believe is calculated at 280 Wh/mi)
    I think if I knew these things at purchase I would have gone with the 100D as I semi-frequently make a ~220mi trip which can get dicey given the above.

    NB: I usually charge to 70% which you can see in the top-left chart.

    Screen Shot 2018-07-02 at 10.54.33 PM.png
     
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  2. TexasEV

    TexasEV Well-Known Member

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    Max REPORTED range is decreasing over time, but the data doesn’t tell you if it’s a real range decrease or if the algorithm that estimates state of charge is becoming less accurate over time. If you only charge to 70% I suspect the latter.
     
  3. ILLCOMM

    ILLCOMM Member

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    #3 ILLCOMM, Jul 3, 2018
    Last edited: Jul 3, 2018
    About once a month I charge to 100%.

    I thought charging to a lower max (e.g., 70%) was good for the battery in the long run. It that not correct?
     
  4. TexasEV

    TexasEV Well-Known Member

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    What’s “good for the battery” and what gives the most accurate state of charge estimate are two different things. While charging to only 70% may theoretically be better for battery longevity, and lab tests may show a statistically significant difference, as a practical matter many years of Model S use has shown no meaningful difference. Remember the early Model S firmware only let you choose charge level of 92% or 100%— the slider came about because of misguided EPA policy on how range was advertised.
     

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