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Road Trip techniques

Discussion in 'California' started by Crispix, Feb 12, 2014.

  1. Crispix

    Crispix Member

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    #1 Crispix, Feb 12, 2014
    Last edited: Feb 13, 2014
    I've been wondering whether or not to post something like this and not sure if it's helpful. I just completed a road trip and the longest leg was San Diego to the Tejon supercharger (and back). It's 200 miles each way and has that big climb over the Grapevine. I used almost exactly 200 rated miles each way. I wouldn't hesitate to make a trip like that again and skip SJC and Hawthorne superchargers.

    Anyway, here are my made-up rules for achieving rated range on a road trip:

    Rule of thumb: "It's the KW, not the MPH!"

    The orange energy meter on the right side of the speedometer is not linear! The energy usage goes from 20KW to 40KW to 80KW. Going just a little bit faster can easily double or quadruple your energy usage! So rather than focus on a specific speed to maintain, I focus on the KW used under various conditions.

    Rule #1: Cruise around 20KW
    On a flat highway, this usually translates to 65-70mph.

    Rule #2: Max out at 40KW
    This is the big one. When cruising uphill, accelerating onto the highway, try to keep the orange line at 40KW. It'll feel slow, but this is where the big energy savings come into play. Just going a few mph faster can easily push you to 80KW and beyond, which will really impact rated range. On most highways, you can travel 65-70mph on a slight uphill and still keep the KW at 40 and under. Climbing the Grapevine, I was going uphill at 50mph in the truck lane and using 40-50KW (yeah, I went a bit over on KW at one point but wanted to at least go 50MPH). It felt dog slow but was only for about 10 minutes or so. Yeah, the other cars will be whizzing past you, but this one makes all the difference.

    Rule #3: Don't go faster than 70MPH
    Wind resistance is a big energy suck at high speed. When going downhill, keep your speed at 70MPH. Coming down from Tejon Pass, I was generating 15-30KW of energy while traveling 70MPH. The net result of rule #2 and rule #3 when going up and down the Grapevine meant my average wh/mile was under 300.

    Rule #4: Don't use cruise control. Do use Range Mode.
    Cruise control messes with the KW usage too much. Cruising at 20KW means my speed will vary a little bit (not enough to mess with traffic) and my rated range is consistent. I set the climate control to range mode and I had the temperature set to 68F. Don't know if it made a big difference or not but I was comfortable.

    I wish the Model S had a "smart" cruise control that would vary speed within a 5% range in order to keep KW usage under control.

    Rule #5: It's ok to break the rules
    Safety first. The whole point of this exercise is to eliminate range anxiety to the point that rated range is achieved on long distances and big hills. If you have to floor it to get past a stinky diesel or get out of the way of something, screw the rules.

    I found that my wh/mile were so easily under control using the above methods that I stopped bothering to hypermile towards the end of the trip just because it was obvious I was going to make it to my destination with plenty of range to spare.

    Next time, going from Tejon to San Diego, I'll just do a 90% charge, no need to wait for a 100% charge.
     
  2. Ugliest1

    Ugliest1 S85: "Sparky"

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    Thanks for this. First road trip coming up end of Feb, will use the ideas. Cheers!
     
  3. Sparrow

    Sparrow S105/ Roadster 189

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    Has anybody studied the energy useage with cruise control? I keep hearing people say not to use it for efficiency. I haven't really done any scientific like measurements, but I have found that cruise control on the same route has improved my efficiency when driving on interstates with 55 mph limits where I am driving at no more than 5 mph over the limit.
     
  4. Ugliest1

    Ugliest1 S85: "Sparky"

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    Should have done a +1 for this, great idea. How do we encourage Tesla to put it on their (...loooooooonnnnnggggg...) list of desired updates?

    And I have to add, it continues to be just incredible to me that, one morning, I could wake up and bingo! there's the added smart cruise control, or whatever other improvement. This is, like, science fiction. We all have a Scotty hidden in the garage fiddling with the dilithium crystals. Two Star Trek quotes come to mind: "Make it so" for the updates, if it were only that easy. And, of course, for those among us who are a teeny bit more impatient, "Come on, Scotty!" "Even if we were under full scale attack I couldn't move any faster, not and maintain a safety factor." -- Scotty, The Naked Time, stardate 1704.2, Episode 7
     
  5. Doug_G

    Doug_G Lead Moderator

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  6. brianman

    brianman Burrito Founder

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    For relatively flat ground, the Model S cruise control is fine for efficiency.

    For hilly terrain, the Model S cruise control leaves a lot to be desired for efficiency. More specifically, keeping the within a +/- 1mph window is too restrictive; +/- 5mph would be preferred, but specified kW limits would be an even better improvement.

    I posted a recommended algorithm months ago. I should probably have sent a link to [email protected] but I can't remember if I already did that or not. :(
     
  7. jerry33

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

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    When you first start driving effectively, cruise control can be as good as or better than manual under some conditions. As your foot becomes more "educated" the advantage of cruise control diminishes, eventually going negative in virtually all circumstances.
     
  8. Kipernicus

    Kipernicus Model S Res#P1440

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    Crispix, great summary!

    I have thought this as well. Maybe if we all start requesting it they might make it happen.

    Send it again!
     

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