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Wh/mi question...

Discussion in 'Model X: Battery & Charging' started by ellisina4, Nov 30, 2016.

  1. ellisina4

    ellisina4 Member

    Joined:
    Jul 1, 2016
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    Location:
    Chicago
    Hello all,
    I picked up my wife's MX P90D (no ludicrous) with 22" wheels in the middle of September. Her VIN is 16,xxx. Since then she drove about 1200 miles with the weather being fairly mild in Chicago, 60s. She drives like a normal person, no lead foot. Her daily commute is about 11 miles round trip, no ttaffic and no expressway. Her average Wh/mi is 445. Is this what people seeing nowadays?
    I did some research on the MX forum and I do understand that 22 wheels will sacrifice 10-15% of range. However, with that usage, we are looking at 200 mile range instead of advertised 250+.
    Any thoughts would be greatly appreciated.
     
  2. TexasEV

    TexasEV Well-Known Member

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    Austin, TX
    That Wh/mi is high. Perhaps she is using the brakes like an ICE instead of regenerative braking?
     
  3. qadaemon

    qadaemon Member

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    Location:
    Sidney IL, Cape Canaveral FL
    Just anecdotal info: I had a P90D with 22's for a loaner awhile back. In town/stop and go it was terrible on energy compared to my 90D, so I would say that is reasonable if that is how it's being driven. My average is going up quite a bit the last month or so anyway; the battery stays at a safe temp while parked and uses a significant amount of energy to do so. Just by watching the energy graph it seems like it's around 55F outside temperature where it really starts using a lot of power. Temps have been below that off and on for a few weeks downstate; I assume the same in Chicago but I don't know.

    My lifetime is ~330 @ ~15417 miles, but that is mostly highway/interstate. My last month average is ~397 over ~1600mi, so that won't last long.

    Things I try to do to keep energy use low & range closer to the number on the dash:
    - Keep speed below 75
    - If possible, draft at a safe distance behind large vehicles on the interstate. The fuel trucks especially make a reasonable difference (~10 Wh/mi in my completely unscientific testing).
    - Use full regen braking as much as possible (more difficult in the city)
    - Use the HVAC _or_ the seat heater/vents. Both at the same time is tons of energy if the dash graph & ammeter are to be believed.
    - On cold days when I need the full range, pre-heat the car while plugged in for 10-15 min
    - Keep tire pressure consistent at the recommended cold pressure. More difficult as of late with 30's overnight and 70's in the day.
    - Try to minimize stops on the interstate. Even pulling off at a rest stop for 5 minutes eats 3-5 miles more of my range than if I didn't stop.
    - Watch the rear HVAC. Even my laptop bag on the middle row seat triggers it to run, so I have it set to off and manually turn it back on when actual humans are there.
     
  4. goneskiian

    goneskiian Active Member

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    My 90D lifetime is 417 with the 22's. Have some 20's on the way so I'm looking forward to the comparison. It is winter though, so I may have to leave them on into next summer to get a real good comparison.

    Keep in mind that for the first 500-600 miles the tires were still in the "break in" phase. You may actually see that number drop some more.
     
  5. cantdecide

    cantdecide Member

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    Location:
    Portola Valley, ca
    Short journeys can make wh/m tough with some HVAC. What is it like for a longer trip?
     
  6. qadaemon

    qadaemon Member

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    Except for the extreme outside temperatures--above 90F or below freezing--HVAC is nearly negligible on long interstate trips in my unscientific testing. Once the cabin is cooled/heated, maintaining that temperature isn't much energy compared to other variables like wind direction, road quality, and traffic speed changes. If HVAC is set to LO or HI though, that's a severe impact.
     
  7. goneskiian

    goneskiian Active Member

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    Yeah, I probably need to use the app to turn on the HVAC while it's still plugged in more often. Oh, and warm the battery too. Especially now that it's consistently under 50*.
     
  8. Sparktz

    Sparktz S 90D, X 90D

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    United States
    Try it out on a longer trip. That short of a commute may be distorting your figures due to the low number of miles to allocate the car start up energy usage (warming the car/battery up). As an example, set one of your dash displays to the trip widget and notice that your Wh/m for the trip starts off very high then goes down as you drive further until it settles at a normal amount.
     
  9. ellisina4

    ellisina4 Member

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    Location:
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    My family took a road trip this weekend and we were extremely disappointed in the range of the car.

    Please see my original post, but this was even more disappointing than the range based on short commute for my wife to and from work.

    Here some details:

    1. It was my wife and I plus two kids, about 360lb total plus about 70lb in the trunk

    2. Tesla MX, P90D (no ludicrous), 22” wheels with Conti DWS06 all season tires

    3. Temperature outside 35F

    4. Temperature inside the car was kept at 70F, all on Auto setting

    5. Seat warmers and steering wheel heater was not used

    6. When we hit the road back home, range was 235 miles.

    7. Navigation was showing us 123miles to get home

    8. Initially it displayed that we will have 29% charge left at the end of the trip but 30 miles into the trip, it went down to 9%. This got me worried as if were to hit traffic, we would be screwed.

    9. Good thing that there was a supercharger on the way, close to home, so we decided not to test out luck

    10. We drove 92 miles without any traffic for 1 hour 20min (to the supercharger), with average speed of 69.5mph (verified by the app on the iPhone). Average power consumption was 524wh/mi

    At that consumption, the range of the car would be 170 miles, at best, instead of 257. That is 66%. Granted 10-15% lost due to 22, but where is the rest...

    Please let me know your thoughts?
     
  10. goneskiian

    goneskiian Active Member

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    You're going to lose at least another 10 - 15% or so at that temperature.

    Check out the range calculator on the Model S page to see how temperature (especially with heat) affects range. It's pretty accurate.

    Also, just so you know, when you slow down (get stuck in traffic) you're going to actually get better range than you would when traveling on the freeway at 70mph. Don't forget that folks have gotten over 400 miles on a charge in an S, but to do so they drove REALLY slow, like 25mph slow.
     
  11. Phil Seastrand

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    This is pretty high, even for the cold and other factors you mentioned. Did you drive mostly with cruise control set or where you maintain speeds? How was your speed compared to the posted speed limit? The Trip Planner assumes you are driving the speed limit so if you were going over, that could be the difference.
     
  12. ellisina4

    ellisina4 Member

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    I maintained the speed myself. It started snowing a little so wanted to control the car.
    Speed limit was 65 2/3 of the distance and 55-60 the rest.
    If the trip planner assumes driving at speed limit, then it needs to be retired. Seriously, who would drive speed limit....
     
  13. ditzpro

    ditzpro Member

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    Had my X for 3 months ..Summer range was close to what I expected but Winter in Michigan has seriously depleted the range ..Very disappointed as I did not know about it ..I hardly do road trips but I am now worried about my daily driving range ..
    It's not enough ..I wish Tesla would offer an upgrade to the 100 D battery for the 90D car ...I don't want to buy the P100D with ludicrous .
     
  14. TexasEV

    TexasEV Well-Known Member

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    The Tesla web site has an interactive thing where you enter the outdoor temperature and it shows the estimated range for each model, both with the heat on and off.

    If you're not doing this already, use the seat warmer and turn the temp down. The car heater uses lots of energy.

    Cold kills range in an ICE too, as cold air has more resistance, you just aren't as aware of it when you can get gas any time anywhere.
     
    • Informative x 1
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  15. Ampster

    Ampster Member

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    Disappointed? In your understanding of physics or that Tesla didn't anticipate every thing we might try to do with our cars? The problem is physics. A lot of factors can reduce range. I towed a trailer with my MX from Portland to LA. Half way there we picked up two more passengers. No one told me either, but it was foreseeable that I would lose range.
     
  16. Solarman004

    Solarman004 Member

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    @ellisina4 , in addition to the factors already mentioned-- 22" wheels, speed, whole cabin heat-- there are a couple other factors likely at play. Reduced road traction from snow, ice or rain will reduce efficiency. Headwind component can also have a big effect.
    I like to pull up Tesla Waze on the internet screen because it shows wind direction and velocity at the car's position (as well as traffic).
     

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