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680-mile road trip planned with cargo carrier on top...

Discussion in 'Model S: Driving Dynamics' started by jessem, Nov 6, 2015.

  1. jessem

    jessem New Member

    Aug 26, 2015
    Lehi, UT
    Hey forum,

    We're planning on taking a road trip in December down to Phoenix, Arizona. I ordered the whispbar roof rack system and have this cargo carrier. I have the 70D (as of about a month ago). We'll be carrying two adults and five kids between the ages of 3 and 11. All said, I just want to make sure my range won't be killed. I'm concerned about loss of range from:

    • the cargo carrier on top reducing aerodynamics
    • the cold weather during the first half of our trip (between 20-50 degrees)
    • the additional weight of the passengers.

    The car will obviously compute where we should supercharge. I just hope it's not off...
  2. Uncle Paul

    Uncle Paul Active Member

    Nov 1, 2013
    Canyon Lake,CA
    With this large, big bag cargo carrier, your mileage reduction will be mostly determined by the speeds you will be traveling. If you see that you are going to be burning watts to quickly you will need to slow down.
  3. Evbwcaer

    Evbwcaer Member

    Jun 21, 2014
    Where are you traveling to and from? I bet that carrier is going to put a big dent in your range, but if there is good SC coverage it won't matter much. I have not noticed additional weight making a noticeable change for range. Cold weather range loss is overstated, IF, you are moving. If you are in traffic or city driving and the heaters are working and you're not moving much, the WH/M will be hit fairly hard.

    Remember that a cold soaked battery won't Supercharge fast, plan accordingly especially for a morning Supercharge.

    Have a good adventure, I picture you like Clark Griswold in the family truckster.
  4. Great Dane

    Great Dane Member

    Jan 31, 2014
    United States St Pete FL
    Anything on top of a roof will kill your millage
    you might have to drive 60 or 55
    just use your trip under the energy app and see how far under
    the line it will be
    I would go out and do a test run to see how bad it is
    weight is of no concern at constant speed unless
    you are driving through mountains
  5. Khatsalano

    Khatsalano Member

    Mar 21, 2015
    San Mateo, CA
    I don't have your setup on my Tesla, but I do on my ICE. Yes, your range will be absolutely killed. You should do some testing beforehand to see what is the increased energy use. Your Rated Miles on your battery indicator will not show less range. You will just use more Wh/mi so you have to take that into account.

    I'm just going to guess, but from your description and link, I'm going to add a 20% penalty at 75mph from my ICE experience. Test it and get back to us!

    - k
  6. andrewket

    andrewket Well-Known Member

    Dec 20, 2012
    #6 andrewket, Nov 6, 2015
    Last edited: Nov 6, 2015
    Definitely don't count on rated. Use estimated on the nav. Once you know what your nominal Wh/mile is you can do the math. Preheat the cabin when you're still plugged in. Consider range mode and use the seat heaters.
  7. CHG-ON

    CHG-ON Still in love after all these miles

    Jun 24, 2014
    Santa Cruz Mountains, USA
    Give yourself a 30% buffer. I use 25% without a roof carrier and it works well for me. Fortunately, they have improved SC coverage on that route. It was pretty bad a year ago.

    I think the old rule applies: slow and steady wins the race. Though it can be painful for those (me) who want to charge on through.
  8. Discoducky

    Discoducky Active Member

    Dec 25, 2011
    Preheat the cabin, keep the climate set to auto at a low temp to keep the windows from fogging, ensure tires are inflated correctly, wax the car ;)

    Always, supercharge to max range, use range mode and use EVtripplanner, but you might want to consider going with a rear hitch and storage instead of on top as it is much more aerodynamic

    EVTripplanner with these settings only shows a max of 150 rated miles used max between the superchargers

    Screen Shot 2015-11-06 at 7.40.55 PM.png
  9. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

    Mar 24, 2013
    Although I doubt that even with your cargo on top and sticking to the speed limits you'll have any problem making each SpC site on the way south, I think it a good idea to monitor each of those legs very carefully and, if any of them appears close, then for the return - "uphill" - leg, consider dropping your speed by some appropriate amount; at a guess 10mph would easily do it. But my guess is that even that won't be necessary...except I've encountered some pretty interesting winds, and snow, in that stretch between St. George to Beaver and beyond.
  10. supratachophobia

    supratachophobia Active Member

    Sep 24, 2014
    Columbus, Ohio
    Based on the whisper and snowboards, I think the cargo carrier is going to penalize you 15%+ at 70mph.

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