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Is this normal ?? - Wh/km literally off the charts !

Discussion in 'Model S' started by Zas, Dec 26, 2012.

  1. Zas

    Zas Sig. Performance #2113

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    So I was at the office today, and my car was parked outside for approx 5 hours.. so when I decided go home, everything was fine.. i got the "Battery is Heating " warning..and so the wh/km was at about 400, ( normal with the weather ).. but then I went through a drive thru for a coffee, and noticed a sudden HUGE surge in the Wh/km - to over 600!.. it literally went OFF THE CHARTS !.. see below images.. it stayed like for a good 5-10 minutes,

    later it dropped back down, and regen came back online.. so i am thinking this was due to battery warming.. but why did take so much energy, and why after after a few minutes of driving ?

    ( Black arrow represents driving the car for a few minutes before hitting the drive thru )
    ( Blue = drive through )
    ( Red = the 5-10 minutes of normal driving afterwards )

    relevant details :

    • it was about -5C / 23F in Toronto
    • i was driving about 60km/hr - i was NOT speeding or exerting the car in any way
    • Climate control was set to 21.5C -but even when i turned it OFF, nothing changed
    • You can see the pattern of the previous days, as cold weather starts usually cause the 400 Wh/km.. but this time it was way too much..

    Anyone have a similar experience ?

    • Capture.JPG Capture1.JPG Capture2.JPG
     
  2. steve841

    steve841 Active Member

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    You see ... we Americans don't convert well to the metric system....
     
  3. Zas

    Zas Sig. Performance #2113

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    Good point! :)

    Here is an American friendly screen shot - its like 900 Wh/mile !!


    Capture3.JPG
     
  4. MikeK

    MikeK R#129, TSLA shareholder

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    I've seen the graph off the chart when first warming the cabin. The initial heat-up seems to use a great deal of energy for a few minutes, then it ramps down rapidly.
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    Keep in mind this is a "per distance" value. If you were creeping or moving very slowly, it makes perfect sense that your energy usage per km/mi is very high!
     
  6. Zas

    Zas Sig. Performance #2113

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    Yes, at the drive thru it made sense, but when i started driving at 60km/hr ( 37 mph ) for a good 5-10 minutes, and it was still stuck over 600 Wh/km ( 900 Wh/mi ).. that when i thought this was strange..

    it only went down when the regen kicked in, which i understand to happen only after the battery has been adequately temperture controlled
     
  7. AnOutsider

    AnOutsider S532 # XS27

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    I've had this happen once when I was gunning it for quite a while
     
  8. Jason S

    Jason S Model S Sig Perf (P85)

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    Or hills.
     
  9. AnOutsider

    AnOutsider S532 # XS27

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    Or gunning it up hills.
     
  10. Todd Burch

    Todd Burch Electron Pilot

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    In that case it was probably powertrain cooling, right?

    - - - Updated - - -

    Looks like you were on the 50 km average setting. Maybe it has to do with how Tesla was calculating the rolling average(?)
     
  11. montgom626

    montgom626 Active Member

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    I have learned that heat takes a lot of power. In a Volt, running the heater takes up to 6 kWh per hour. A/C, 1.5 kWh per hour. And these are rough estimates. So, if you think your MS is sucking a ton of electrons per hour with the heating element on, you are 100% correct. During the cold months, your "mileage" on electrons will drop a lot. Batteries are like people. If you don't like the temp, your battery will not like the temp. Too hot, too cold, not good for conserving kW for driving. All the kW are being directed to heating the car and the battery in cold weather. And it takes a lot of power. So, avoid really cold places for EV use ;-) . In Wisconsin, I know that during 3 cold months of the year, my miles per watts will suck.
     
  12. Zas

    Zas Sig. Performance #2113

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    Yes, this seems to be the case, I'll keep an eye on this as winter creeps in, and I'll report back with some numbers...as this just seemed too high today.
     
  13. Todd Burch

    Todd Burch Electron Pilot

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    This all depends on whether resistive heating or heat pumps are used. Resistive heating is much less efficient. Model S uses a heat pump for heating the battery, as I understand.

    That said, this extra power is only needed for a few minutes until the drivetrain is generating enough of its own waste heat, even in cold climates.
     
  14. montgom626

    montgom626 Active Member

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    I feel your pain. I can get 50 miles on 10 kWh charge during the warm weather and 30 miles during the cold weather (In My Volt). I am guessing that my Model S will do the exact same thing. It is just the nature of batteries. I am sure as it gets colder, the current low end of 30 will get lower in my Volt. When folks in their MS describe a drop in miles (and SOC) with cold weather and use of heater, I have been there and done that. I understand. With the first hint of warmth in Spring 2013, with temps in the 50 degree F range you will think you have become the best hyper-miler on the planet. :)
     
  15. EcoHeliGuy

    EcoHeliGuy Member

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    Did you turn on heating elements like mirrors or rear window? Rear window defog is on of the highest drawing items in a car.
     
  16. Zas

    Zas Sig. Performance #2113

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    #16 Zas, Dec 26, 2012
    Last edited: Dec 26, 2012
    No, I did not, and I even turned climate control and heated seats OFF for a while...no change...it only dropped when the regen came back online, which makes me believe all that energy was used to heat the battery pack.
     
  17. brianman

    brianman Burrito Founder

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    Just another data point...

    Back out of my driveway (slowly), drive about 15 mph up to the first stop sign in the neighborhood, turn.

    For that sequence (every weekday), I see about 1200 Wh/mi. usage and then it drops immediately to something sane after about 3 car lengths.
     
  18. ddenboer

    ddenboer MODEL X #1770

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    I saw the exact same thing when leaving the factory service center today. My car was sitting out all day (6+ hours) and it did this for the first 2-3 miles and then dropped. It took alot of driving to bring my average to where I like it :)
     
  19. dailydriver

    dailydriver Member

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    LOL. Up hill, down hill, flat - I've pegged the meter a few times too. :wink::redface:
     
  20. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    Yes, I think it's normal behavior and the graph just reflects the way Tesla is calculating the rolling average of an essentially infinite Whr/mile when you're not moving. Tonight I was out driving while the OAT was under 15 deg. F. and saw for the first time the warning message saying that the battery was heating. At the next stoplight I saw a total at-rest draw of about 10kW, perhaps half of which would be due to battery heating and the other half to cabin heating, seat heaters, lights, and other systems. For a 15-mile, stop-and-go trip that would 'normally' consume less than 350 Whr/mile, I averaged 500.
     

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