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Model X Range Improvement Due to Drafting & Suspension Setting

Discussion in 'Model X: Battery & Charging' started by GordonBremer, Aug 19, 2016.

  1. GordonBremer

    GordonBremer Member

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    Summary Results at 65 MPH: Drafting at any TACC setting (1-7) improved range 5%. (Difference between settings 1 & 7 was surprisingly and negligibly small.) Lowering suspension from LOW to VERY LOW improved range 4%. (These may not be additive.) For a fully-charged (250 mile) battery, drafting and suspension could add as much as 22 miles.

    Objective: Determine any range improvement of a Tesla Model X when following behind an 18-wheel truck at various distances.

    Car: Tesla Model X Signature, P90D, 20 inch tires @ 42lbs, A/C: on, Range Mode: on.

    Technique: Follow an 18-wheel truck at distances determined by the Tesla Traffic Aware Cruise Control (TACC) following settings. Record average kW/mile over 5 miles. Utilized an Interstate segment about 7-miles long with flat terrain, no over-passing, sea level, 88 degrees, no significant wind, Insane Mode, Range Mode: ON. Recorded results in both road directions. Set the average energy consumption display to 5 miles and monitored the graph to ensure no peculiarities. Identified a truck traveling at 65 mph. Set the TACC to 70 mph and set the TACC following distance. Approached the truck until the car speed dropped to the speed of the truck. Followed the truck for at least 5 miles, avoiding any nearby vehicles that may affect wind resistance. Documented the average energy consumed over 5 miles (kWh/mile) and recorded the speed. Repeated above for various TACC settings and suspension settings.

    Note 1: trying to only judge improvement by only observing the graph can be very difficult and misleading.
    Note 2: Expected improvements at higher speeds would be greater.
     
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  2. systemcrashed

    systemcrashed Please Reboot

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    Very helpful, confirms what I am experiencing. I know some of us here would love to see the raw data too.
     
  3. ccutrer

    ccutrer Member

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    Oh definitely. On my first road trip, I was between Tremonton, UT and Twin Falls, ID in some mountainous terrain, speed limit 80. I quickly realized how much going 83 was going to kill my range, but drafting behind a semi at 77 brought my expected arrival charge up from 9% to 20% or so.
     
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  4. GordonBremer

    GordonBremer Member

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    Here is my raw data report.
     

    Attached Files:

  5. xkwizit

    xkwizit Member

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    While drafting would have helped, wouldn't just dropping the speed from 83 to 77 increased the SOC?
     
  6. ccutrer

    ccutrer Member

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    Both helped. Once I felt confident enough I passed the semi and sped up -- slightly. Definitely not scientific as I didn't record actual usage and points where I changed variables.
     
  7. jrichey

    jrichey Member

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    Love the tips. Guess I have a question now. With the improvement by putting the suspension in Very Low, are we able to override and do that on the highway for long periods of time? Wasn't sure if there were any concerns with driving it that way. Secondarily, guess I wonder why at highway speeds it wouldn't already move to that level.
     
  8. vandacca

    vandacca Active Member

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    At the lowest setting it becomes vulnerable to road debris. In the beginning, it worked that way, but there were 2-3 model-S that hit road debris (e.g. tow hitch) which punctured the battery casing and caused the vehicle to catch fire.

    For a period of time, they restricted the lowest setting until the software was updated to allow user-suspension-settings. Also, they reinforced the battery plating.
     
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  9. Roentgen

    Roentgen Member

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    Aren't there issues with camber and tire wear with the lowest settings too (on the S)? I don't know if this is still an issue, or if it applies only to the S and not the X. Both cars being on the same platform, I would think the problem (if still present) would apply also to the X.

    Advanced tire wear and replacement would negate any routine range benefit I would think.
     
  10. vandacca

    vandacca Active Member

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    I've seen some brief mentions about tire wear at the lowest suspension settings in the X forums, but I suspect there is a lot more discussion on the S forums (I haven't checked yet). I agree, that this behavior would likely be the same on both X and S.
     
  11. RossRAllen

    RossRAllen Member

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    Drafting a truck increases your potential for a stone into the windshield or body. That and the safety issues: not for me.

    My SC Mgr said that low and extra low suspension settings could result in camber changes causing more wear on the inside if the tires.

    Power required to overcome drag goes as the cube of velocity, so slowing from 75 to 70 mph saves about 23%. Slow down just a bit and forget slipstreaming big trucks.
     
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  12. Jeff Andrews

    Jeff Andrews Member

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    Also put your tire pressure at 45 instead of 42 and that might help a tiny bit.
     
  13. GordonBremer

    GordonBremer Member

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    Regarding the potential dangers of drafting a truck, note that at a TACC setting of #7 that the following distance is about 80 yards at 65 mph. "Do or don't" is up to each driver. Personally, I find 80 yards to be very comfortable and safe.
     
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  14. systemcrashed

    systemcrashed Please Reboot

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    Tire wear at the very low SAS setting is irregular with the Model X as well, My MX is at the SC right now exhibiting uneven inner tread wear, I have been driving hwy miles between low and very low. They are performing an alignment as well. This camber could possibly increase consumption as well.
     
  15. Rashomon

    Rashomon Member

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    Range effect on speed is proportional to velocity-squared. Aerodynamic power requirement is proportional to V-Cubed, but at a higher speed you're covering ground more quickly in proportion to the increased V, reducing the time at the higher power level. That reduces the range effect to the V-squared.
     
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  16. systemcrashed

    systemcrashed Please Reboot

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    But increases to the V-cubed, so there has to be a "sweet spot", correct?
     

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