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Real World Comparison of a S85 to an 85D Efficiency

Discussion in 'Model S: Battery & Charging' started by breser, Mar 7, 2015.

  1. breser

    breser AutoPilot Nostradamus

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    #1 breser, Mar 7, 2015
    Last edited: Mar 9, 2015
    Today I drove from my home in North Bend, WA to the Coeur d'Alene, ID SuperCharger. Joining me in this was another TMC member ThortsMD who drove his Model S 85 with me. We met up at my house a little before 7am. Before we set off we made some effort to try to eliminate as many variables (i.e. differences) as possible.

    State of Charge

    His car is a fairly early (VIN in the 6XXX range) and has some battery degradation so we couldn't use percentage of charge to compare even though they have the same size battery. We also couldn't directly use rated range to compare since an S85 and 85D have different rated ranges. So we used the combined EPA kWh/100 miles number to estimate charge in the battery. He had 184 rated miles which when multiplied by the 0.38 kWh/mile comes out to 69.92 kWh in his pack. An 85D uses 0.34 kWh/mile which comes out to 205.6 miles so I charged my battery to 206 miles of range. It's hard to say if this is a valid way of calculating the energy in the battery. It's also not really clear if this is important.

    Ultimately we gave up on even bothering with this after the first leg. The S85 had a A pack and charged slower and we had breakfast and it was going to be pain to try and manage this so we just didn't worry about it much on all the other legs.

    Other Driving Parameters

    We agreed to use 70°F as the climate setting. We agreed to drive at 73 mph excepting for areas where the speed limit drops and there's some construction through the pass. Both cars have 19" wheels. Mine has the Michelin Primacy tires, his had Goodyear Eagles. I had my fiancée along, so I had an extra passenger. I have tinted windows, he does not (which might some difference in the warmer part of the afternoon). Both cars have air suspension (but I didn't think to ask what his settings were for lowering the car). Neither car used range mode in any of the driving we did.

    For the legs to Coeur d'Alene the S85 was in the lead and the 85D followed with TACC. For the legs back to North Bend we reversed things and the S85 followed the 85D.

    Data

    We probably didn't do the best job keeping track of data. I did have VisibleTesla running for my car which provides a lot more data but ThortsMD had never used it and given the recent access issues with it we didn't bother to try getting it working for his car. Unfortunately we didn't track exactly the same info however we both kept track of the most important bits which was the kWh used and the Wh/mile. I kept track of the distance of the drives and the rough temperature during the drive.

    Leg Distance in miles
    Temperature S85 kWh Used S85 Wh/mile 85D kWh Used 85D Wh/mile
    North Bend to Ellensburg 77.5 50°F leaving North Bend (not entirely sure this is accurate but it's what the car said), 34°F at summit, 37°F at Ellensburg 28.7* 380* 30.8 397
    Ellensburg to Ritzville 114.0 46°F leaving Ellensburg, 54°F arriving Ritzville 40.3 353 41.6 365
    Ritzville to Coeur d'Alene 92.2 59°F leaving Ritzville, 59°F arriving Coeur d'Alene 29.8 323 31.1 337
    Coeur d'Alene to Ritzville 91.9 61°F leaving Coeur d'Alene, 63°F Arriving Ritzville 27.8• 303 30.7 334
    Ritzville to Ellensburg 113.9 67°F leaving Ritzville, 62°F arriving Ellensburg 35.2• 309 38.4 338
    Ellensburg to North Bend 77.3 59°F leaving Ellensburg, 48°F arriving North Bend 23.9 310 25.9 336
    Total 566.8
    185.9• 329 198.5 350
    * This number should be slightly lower since ThortsMD missed resetting the trip and didn't charge at my house before leaving. He realized this roughly a third of a mile into our trip. So to some extent this first leg is suspect. However, since I hadn't driven any since the previous day I think some of the warming up of the car I did by way of running the climate system in my garage before leaving was included in this number. So I think this whole leg is suspect.

    • ThortsMD apparently didn't write this information down. I've calculated these by using kWh = (Wh/mile * miles) / 1000. Unfortunately the miles are from the 85D and not the S85 so it's not as accurate as it could be but close enough. The Total values are what ThortsMD provided me but he adjusted them slightly to deal with the trip not being reset till about a third of a mile in. So between that and the missing values it won't add up exactly.

    Trip Info for 85D from Visible Tesla

    This is links to the HTML exports of the trips between superchargers from VisibleTesla. The first and last trips to/from my home are omitted since this includes detailed mapping information. Yes I'm sure someone can figure out where I live anyway, please don't feel the need to prove this by being creepy. Distance is a little off here because VisibleTesla cut the trips in slightly different places. I don't have the same information for the S85 since it wasn't being monitored by VisibleTesla. There is also some gaps in the data due to the lack of cellular service along some of this route.

    Ellensburg to Ritzville
    Ritzville to Coeur d'Alene
    Coeur d'Alene to Ritzville
    Ritzville to Ellensburg

    Conclusions

    It's hard to make any conclusions. The 85D clearly used more energy but the following things might have contributed to that.

    • The 85D started the trip with 1,556 miles on the odometer. It's possible that various parts haven't had enough mileage to settle in. I believe the EPA tests were done with vehicles had 3,000 miles on the odometer.
    • Difference in the tires. Different brands of tires on top of the 85D tires being relatively new and the S85 tires nearing time to replace them.
    • The extra passenger in the 85D.
    • TACC being less efficient than straight up cruise/human driving. There are times when it does things less efficiently. However, the trip from Ritzville to Ellensburg with the 85D in the lead there were only two occasions where TACC slowed below the set 73 mph due to traffic. Looking at the data now however, I'll notice that the 85D was closer when it was following on TACC cruise.
    • The 85D itself could just be a tad less efficient when not used in range mode. We didn't do any range mode testing this time.

    When we were driving this today it seemed like we were a lot further off than sitting here now looking at the data. I suspect that the extra passenger really was the difference.

    I can probably publish a lot more data from my 85D, but without the corresponding data from the S85 I'm not sure how interesting it is. I suspect we'll do another drive sometime in the future compare further.
     
  2. vvanders

    vvanders Member

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    Any reason you didn't use range mode? My understandings is that's where the 85D is supposed to shine.
     
  3. Andyw2100

    Andyw2100 Well-Known Member

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    #3 Andyw2100, Mar 7, 2015
    Last edited: Mar 7, 2015
    Yes, you definitely were not getting most of the benefits of torque sleep with range mode off. There have been several posts here that talk about that. Jerome Guillen has been the source for some, indicating that while there are some efficiency benefits from torque sleep with range mode off, there are significantly more with range mode on. I also posted something after speaking to a rep at the Tesla 800 number. I'll look for that, and edit this when I find it.

    Edit: Found it: P85D vs. P85 Efficiency Testing, Take 2 - Page 11 (Bold just added to highlight most relevant part)

     
  4. Nevek

    Nevek Overt Member

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  5. dennis

    dennis P85D

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    That's the second time Andy has been educated about NVH for the same post, with the same Wikipedia reference!

    P85D vs. P85 Efficiency Testing, Take 2 - Page 12
     
  6. Andyw2100

    Andyw2100 Well-Known Member

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    You make it sound like I didn't pay attention or something. I was only copying my post from the other thread above, for the relevant part. I didn't say, "Oh, and by the way, I'm still trying to figure out what those letters were." I did point out that it was an old post. I guess I could have added a note to say that later in the thread someone pointed out that the abbreviation was NVH. Oh well.
     
  7. NOLA_Mike

    NOLA_Mike Active Member

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    This part probably only applies to the P85D since it appears the 85D has the same motor front and back.
     
  8. breser

    breser AutoPilot Nostradamus

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    Sure. Because nobody feels compelled to use range mode unless they're really pushing the range of their vehicle in an S85. None of these legs were even close to pushing the range of the vehicle.
     
  9. RLO

    RLO New Member

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    @Breser:
    Thank you for doing this test, Very intresting!

    I have not seen any similar test anywhere else yet but I sure do hope to see more tests and may be results more in the favour of the D model when it comes to range. Theory from Tesla is one thing, results experienced by real users is another story.
     
  10. mspohr

    mspohr Active Member

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    I left range mode on since my initial hypermiling road trip in my 85D.
    Could someone explain the pros and cons of this setting?
    I haven't noticed any issues except power and regen are limited when battery is cold (but I can still accelerate way too fast).
     
  11. breser

    breser AutoPilot Nostradamus

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    Power and regen are limited when the battery are cold regardless. It seems that regen mode disables battery warming when heating the car from shore power. Doesn't as aggressively warm the battery. Limits the climate settings some. Does something with Dual motor cars and torque sleep. Frankly, Tesla has not been very informative about the advantages and disadvantages of it.
     
  12. ModelS1079

    ModelS1079 Member

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    There is a significant difference in the heating level - fullness, temperature, fan speed - with Range Mode. Also w preheating via the phone app, it heats more slowly, less fully. That said, I leave it on Range Mode much of the time, and virtually all days when it's not crazy cold (e.g., -19 degrees a fews weeks ago), and virtually all of April through November, unless really hot and more AC desired.

    To be clear, the difference is only evident with extreme external temperatures.
     
  13. richkae

    richkae VIN587

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    I think the difference you reported could easily be explained by the tires and the tires alone.

    If the experiment is done again I would recommend using the same brand of tires, with the same inflation pressure, tread depth and ideally the same age.
     
  14. breser

    breser AutoPilot Nostradamus

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    Changing tires is a bit far to go for a fairly casual comparison. We did try to control variables we could do reasonably but our real purpose was to head out to the new super charger in Coeur d'Alene and try it out.
     
  15. Matias

    Matias Active Member

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    So what the result was?
     
  16. jerry33

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

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    Inconclusive. Too many different variable differences between the two test cars.
     
  17. dennis

    dennis P85D

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    I wasn't implying that you are a slow learner. I just thought it was funny that someone else referenced the same Wikipedia post. That's all.
     
  18. mspohr

    mspohr Active Member

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    I don't understand why it would limit battery heating on shore power since, well, it's shore power, not battery power.
    I agree that there needs to be better information about range mode.

    - - - Updated - - -

    I don't understand why it would limit battery heating on shore power since, well, it's shore power, not battery power.
    I agree that there needs to be better information about range mode.
     
  19. Matias

    Matias Active Member

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    I just read tire test comparing brand new summer tires. The best vs the worst had 5% difference in energy consumption. So it is very difficult to get reliable results with different tires, if differences are small.

    - - - Updated - - -

    I would still like to hear the numbers.
     
  20. breser

    breser AutoPilot Nostradamus

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    I went ahead and added links to HTML output of the trips from VisibleTesla on the initial post.
     

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