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Wh/Km, Projected range and Energy Screen

Discussion in 'Canada' started by znino, Dec 22, 2012.

  1. znino

    znino Member

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    Ok, I am a little confused and concerned with the information I am getting on my Energy screen. I have a Roadster, used it all last winter and I understand the relationship between Wh/Km and projected or estimated range etc. I also understand that the Model S will draw more power than the Roadster being heaver etc but here is what I have been seeing consistently over the last 24 hours:

    50Km Average Wh/Km of 300 and above. Has even been over the 600 mark for 25 km average this evening. I have been driving very slowly, speed limit on neighborhood roads with some packed snow in some areas. HVAC running with little fan and 21 degree temp with outside temp around -5.

    The graph, when set to show average upon coming home tonight is showing me an avg Wh/Km of 375. Ideal range is showing 257km. Projected range is showing 100 Km. The battery icon in the speedometer is looking like it is at about 70% (Green). I think that the computer is using an average of 375 indicated and coming out with 100Km projected but really, with almost 3/4 of the battery and driving in the conditions and the speed I am, I would expect the Wh/Km to be quite a bit lower....maybe just over 200 and the projected range to be higher. How is my Wh/Km over the past 5 Km coming back from a movie over 600??? In comparison, my Roadster today under same conditions over 50Km has an average of 190 Wh/Km.

    I almost feel like saying it feels like maybe they changed the SW to allow units to be in Km but somehow the displayed Wh/Km values are still in miles (although they display as km). If I take the 375 and divide by 1.6 I get a value that makes much more sense. If this is what is going on, then naturally the projected range would be calculated using erroneous numbers and give false readings.

    I also see the IDEAL line on the graph at around 250. That also seems high. I spoke to Mark in service briefly tonight who seemed to say that the values should not be that much different from the roadster and could even be better on snow.

    Anyone have similar results or insight?
     
  2. AndrewBissell

    AndrewBissell Member

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    Try switching your display to miles and see if the numbers change.
     
  3. znino

    znino Member

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    I did. They do change and get even higher which baffles me and would suggest no software bug but still, something doesnt feel right. Even using Tesla's own calculator going 45 MPH, 0 degrees C and Heat, it predicts a range of 339 Miles on a full charge. My green battery is not going down at any rate close to what it should if the Wh/Km and projected range based on 50Km was accurate. I am only at 70% and drove quite a bit today so something is off.
     
  4. Doug_G

    Doug_G Lead Moderator

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    One thing I can tell you - the "Rated Range" line on the graph is in the wrong place. It doesn't scale properly when you switch to km. That was a major source of confusion for me at first, until I realized it was 60% high (already reported to Tesla).
     
  5. znino

    znino Member

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    Doug, are you talking only about the Rated range line or is it the same problem if you switch it to show Ideal range? My understanding is that Ideal Range is Tesla's Optimal conditions range and rated range is some Transport Authority range based on specific criteria they use.

    By the way, What kind of average are you seeing for the Wh/Km so far?
     
  6. brianman

    brianman Burrito Founder

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    I'm curious as well on this one. And if you're feeling energetic (pun accidental) the Wh/mi. converted number is interesting to some of us as well.
     
  7. Doug_G

    Doug_G Lead Moderator

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    So far I have my car set to Rated Range display mode, to provide a more conservative indication of range. I haven't checked the Ideal Range line, but I wouldn't be surprised if it had the same bug.

    The car says I've averaged 258 Wh/km so far (for now I'm not resetting Trip B). That's a mixture of pampering for the road trip home after delivery, driving in horrible conditions, and some NOT pampering today.

    Today the roads were in better condition and the weather was colder (around -8C). I started out with a cold pack and limited regen in the morning, used the cabin heat as needed, drove at full freeway speeds, and tried a few heavy foot maneuvers. My Wh/km was over 300 today.

    I'll leave it to the Americans to multiply by 1.6.
     
  8. brianman

    brianman Burrito Founder

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    412.8 Wh/mi.
    480.0 Wh/mi.
     
  9. pbrulott

    pbrulott Member

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    DouG, that sounds ok in winter temp (-8C), heat on, freeway speed and some heavy foot (+55% vs EPA 308 wh/mi)

    Using the Go Electric simulator and 308 wh/mi as the EPA consumption:

    Gross it up by 2.5% per 10C lower than 20C (around 7.5% hit at -8C)
    Heat on: 15% hit
    Consuming 8% more per 8km/h above 88km/h (you must have driven up to 110-115km/h) => 24% hit

    Total: 7.5% + 15% + 24% = 46.5% leaving some wh/km for the heavy foot and lower regen

    Now as for zhino, I can't explain it. Concerning. keep us posted. glad you have the Roadster comparison
     
  10. znino

    znino Member

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    Here is a little update concerning the line on the graph that says ideal or rated. Charged the car up last night. This morning I have 446 ideal or 387 rated.

    when I look at the graph in ideal mode it seems to be around 270 and when I switch to rated, it is at about 300.

    If I put it on Instant, the projected range shows 325Km but the instant value is just over 200 Wh/Km on the graph. Since the Rated line is above that, I would have expected my projected range to be above the shown rated range. Since it is not, this is just one more evidence that the horizontal rated or ideal lines on the graph are wrong.

    So Doug when you said that this line on the graph was 60% too high are you saying that for me it should read 168 and 188 respectively? That would make more sense anyway. The 168 Wh/Km for ideal range would compare to about 143 Wh/Km for the Roadster so about 17% higher.
     
  11. Al Sherman

    Al Sherman It's about THIS car.

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    Info and/or link on the Go Electric Simulator please?
     
  12. Spenny818

    Spenny818 Member

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  13. Doug_G

    Doug_G Lead Moderator

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    #13 Doug_G, Dec 23, 2012
    Last edited: Dec 23, 2012
    Right ballpark. By the numbers (assuming you really can use the full 85 kWh):

    EPA Rated 85000 Wh / 265 miles = 320 Wh/mile / 1.6 miles/km = 200 Wh/km

    Ideal 85000 Wh / 300 miles = 283 Wh/mile / 1.6 miles/km = 177 Wh/km

    The graph at Model S Efficiency and Range | Blog | Tesla Motors suggests approximately 55 mph => 270 Wh/mile (169 Wh/km)

    That suggests 81000 Wh usable.

    EPA Rated 81000 Wh / 265 miles = 306 Wh/mile / 1.6 miles/km = 191 Wh/km

    Ideal 81000 Wh / 300 miles = 270 Wh/mile / 1.6 miles/km = 167 Wh/km
     
  14. Doug_G

    Doug_G Lead Moderator

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    Today I ran some errands, whole bunch of very short trips, accumulating a mere 11 km. However the pack was cold enough for very high regen limits when I started. By the time I got back home some hours later the regen was barely limited. I suspect the car is intentionally heating the pack, presumably the logic is that it will be more efficient in the long run. However I had no long runs today, and as a result I got 458 Wh/km.
     
  15. znino

    znino Member

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    So I guess the battery management in the S is quite a bit different from Roadster because I never got anywhere close to those numbers with the Roadster, even considering the relative difference in battery size. I think the roadster is roughly 145 Wh/Km so even if the Model S uses about 15% more ideal (according to your calculations) I would expect my Model S usage to be higher than the roadster but not double, as is now the case over my average. I think something else is going on, perhaps some different management with the heating of the pack as you suggested.
     
  16. pbrulott

    pbrulott Member

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    zhino, if I'm not mistaken, the TPMS has not been calibrated in the current deliveries with Winter tires. Have you checked if your TMS tire pressure is fine. That could explain higher consumption.

    I also read somewhere that 5 hours sitting at -5C got the Rated km from 100 to 70... that seems like high. TM needs to find a better solution for colder climate

    PB
     
  17. znino

    znino Member

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    I have not checked tire pressures and I'm on vacation now so ill have to continue investigating things when I get back. Could be affecting things although mark assured me that he personally built all the winter tire sets and the pressures were to spec.
     
  18. LazMan

    LazMan Member

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    A few things I don't understand:

    Does the solid line on the energy app ever change? Shouldn't it be static, about 200/km. It seems to move for me.... I think.

    Also, if you set the display to average (not instant) and the rated (solid) and dotted line match up, shouldn't the projected km match what is shown for rated range by the speedometer?
     
  19. Doug_G

    Doug_G Lead Moderator

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    The "rated" line should stay at 200 Wh/km; however, it has only been in that correct location since version 4.3 was released. On earlier versions including 4.2 it was plotted at about 300 Wh/km, which is the number for Wh/mile. Evidently they missed that for the metric conversion (someone hard coded it!).

    Yes, if you can get the line to match up then Projected should equal Rated. However if you're on 4.2 then it won't work!
     
  20. Zextraterrestrial

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    I think the 'Projected average' uses .1 mi (or km) updating for the graphic and the dash 'rated' is continuously updating because they are usually a little different unless I have been driving steady on flat land( not very often)
     

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