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EV Trip Planner website estimate vs. P85D actual energy use

Discussion in 'Model S: Battery & Charging' started by thekomet, Jan 4, 2015.

  1. thekomet

    thekomet Member

    Joined:
    Oct 31, 2014
    Messages:
    9
    Location:
    AZ
    Everyone here seems to appreciate data, and I've been curious how accurate EV Trip Planner is in estimating energy use for the Model S. I just purchased a P85D and since the EV Trip Planner website does not have a profile specific for that model, I was even more curious to see how the this site would work for my car. Here's how I did the comparison:

    EV Trip Planner site
    EV Model: Model S/P (21" wheels)
    Speed multiplier: 1.0
    Cabin temp: 36 deg F
    Exterior temp: 36 deg F
    Payload: 300lbs

    Payload is high. I'm 220 and there is probably only another 10-15 lbs in emergency equipment in my car, but there you go.

    Car variables
    The exterior temp according to my car was 31-37 degrees. I didn't use any climate control. Kept the driver side seat heater at level 2 and only used the rear defroster for about 10 minutes. Glad I remembered to bring a jacket!

    I used cruise control to exactly match the average speed listed in the "Details" tab of EV Trip Planner which meant at times I was going slower than necessary on city streets but I wanted to be as accurate as possible. I accelerated gently when leaving a stop light or stop sign and when passing a truck.

    Results
    From my place of business to the Casa Grande supercharger (to test out charging there) was 38.3 miles with 230 feet of net elevation change (472 up and 243 down) according to EV Trip Planner. Actual mileage was 38.5
    Total energy used (estimate): 14.3 kWh (374 Wh/mi)
    Total energy used (actual): 15.2 kWh (395 Wh/mi)
    % over estimate total kWh: 6.29%
    % over estimate Wh/mi: 5.61%

    From Casa Grande supercharger to my home was 57.0 miles with -115 feet of net elevation change (462 up and 577 down) according to EV Trip Planner. Actual mileage was 57.4
    Total energy used (estimate): 20.6 kWh (361 Wh/mi)
    Total energy used (actual): 21.1 kWh (367 Wh/mi)
    % over estimate total kWh: 2.43%
    % over estimate Wh/mi: 1.66%

    Some conclusions that jump out at me:
    1. The P85D can be driven in a way that energy efficiency is close to the P85.
    2. The P85D seems to use more power climbing than is estimated for the P85. I think this data is inadequate to draw much of a conclusion, my guess is that the P85D is more power hungry climbing than a P85
    3. EV Trip Planner seems fairly accurate even though there is not a P85D specific profile. I think I can trust it when I travel to Los Angeles this month.

    Most importantly, it took a lot of discipline not to drive this car the way it wants to be driven :)
     
  2. Bighorn

    Bighorn Member

    Joined:
    Jun 19, 2013
    Messages:
    481
    Location:
    WY
    Early tracking of a cross-country trip in a P85D, over the first 1200 miles, is showing about a 4% reduction in efficiency vs evtrip data for a P85. Pretty close to your findings.

    Cross Country Winter Adventure - Tesla P85D
     
  3. CHGolferJim

    CHGolferJim Member

    Joined:
    Jan 28, 2014
    Messages:
    842
    Location:
    Chapel Hill, NC
    Not sure if it was a D owner, but someone posted that a 1.1 speed multiplier made the EVTripPlanner projection more accurate to his experience.
     
  4. svp6

    svp6 Member

    Joined:
    Sep 6, 2014
    Messages:
    297
    Location:
    MN
    Here are my tryouts - keep in mind that last 2 trips had wind ~20-25 mph. I Have 985D with 19" Tesla Winter tires. If you use EV TripPlanner with the Tesla S/P 21" selection, it looks reasonably good at decent temperatures. The very low temperatures are completely off - both directions; trip 4 I had 563 vs 460 estimated (72 mph); return was same route at 65 mph, and I had 413 Wh/mi vs 460 estimated. This is in part due to the battery being cold (would not allow complete regen) for most of trip 4, while warm for trip 5, and possibly due to favorable wind direction on trip 5. Bottom line, in extreme conditions calculators are to be taken with caution....

    speed
    distance
    kwh
    Wh/mi
    EV TripPlanner at 1.1 (for 72 mph) and 1.0 (for 65 mph)
    estimated range from 100% (assuming 75 KWh available)
    temp
    wind
    snow/rain
    76
    94.5
    43.6
    461
    451
    162.7
    30
    72
    39.3
    16.4
    417
    418
    179.9
    32
    65
    43.9
    16.3
    372
    410
    201.6
    33
    72
    19.4
    10.9
    563
    464
    133.2
    1
    some
    65
    25
    10.3
    413
    466
    181.6
    1
    some
     

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