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Ascent of Mt Mitchell and the Magic of Regen

Discussion in 'Model S' started by SarahsDad, May 7, 2014.

  1. SarahsDad

    SarahsDad Member

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    Location:
    NC
    It was a beautiful day here in the Carolinas so decided to see if I could make it up to Mt. Mitchell and back, 214 miles round trip.

    IMG_3264.jpg
    Mt Mitchell EV Elevation.jpg

    Figured I could probably make it but wasn't sure about the almost 6,000ft altitude change, so took it easy the first half, drove the speed limit, Range Mode, conservative driving.
    Started with 266mi Rated Range (only dropped to 265mi after 4mi when I took this shot).
    IMG_3260.JPG

    Made it to the top OK even burning 610Wh/mi over the last 30 mi.
    IMG_3261.JPG
    IMG_3267.JPG


    Then the fun part - went downhill almost 25mi while adding 7mi of Rated Range.
    IMG_3295.JPG
    IMG_3293.JPG

    Drove the rest of the way without being conservative (5-10MPH over the limit, Range Mode off), and still ended up back home with 51mi remaining and a trip average of only 281 Wh/mi.
    Pretty amazing...
    IMG_3301.JPG
     
  2. Mhotep

    Mhotep Member

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  3. Canuck

    Canuck Active Member

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    Great info and looks like beautiful country.
     
  4. drewnick

    drewnick Member

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    Enjoyed the analysis. We were just up in Asheville (from Fla) in an ICE and I pondered the effect of the mountains. Looks like it (kind of) balances out in hilly driving. Saw two Tesla's in Asheville.
     
  5. AnOutsider

    AnOutsider S532 # XS27

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    That's pretty cool. Math isn't my strong suit, but did the descent make the mountain a net zero or?
     
  6. SarahsDad

    SarahsDad Member

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    @AnOutsider

    On the one hand it does seem I had almost a net zero energy adding the up and down together - If I burned 610 Wh/mi over the last 30 mi up and averaged 387 Wh/mi for the entire first 106.4mi half of the trip, that means the other 76 or so miles I had to average about 299 Wh/mi ((610*30)+(299*76))/106=387. Since my average Wh/mi was 294 after the initial descent (and 281 for the entire trip), it makes it look like the elevation was cancelled out.

    But since physics has these rules like conservation of energy and stuff like friction, I know it wasn't a "net zero".

    Other posters have said you regain about 81% back on the way down (assumes a 10% friction loss from motor to tires, and a 10% friction loss during regen from tires to battery - 0.9X0.9=0.81)
     

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