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Electric Vehicle Technology Roadmap And grid integration April 27th, 2011 JB Straubel

Discussion in 'News' started by emq, Dec 2, 2011.

  1. emq

    emq Member

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  2. jcstp

    jcstp Active Member

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    verry interesting!
     
  3. Todd Burch

    Todd Burch Electron Pilot

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    That last slide shows energy losses with tires almost as large as aero with highway driving. That surprises me.
     
  4. Eberhard

    Eberhard #421 Model S #S32

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    but you see, that the losses with the tires are almost constant, but aero goes up with square of speed
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    Which is exactly why it surprises me that even at highway speeds tire losses aren't significantly less than aero losses.

    They must have used 55mph as their highway speed--relatively slow in the real world.
     
  6. ChadS

    ChadS Petroleum is for sissies

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    I'm still trying to sort some of that out, too. The information presented seems to be similar to what's in the third chart in this blog: Roadster Efficiency and Range | Blog | Tesla Motors

    The aero drag does seem to be about what that chart shows for 55mph. But the tire friction seems notably higher at either speed. Drivetrain seems a little higher (if you add all the pieces together in the older chart). Maybe it's updated for Model S instead of the Roadster?

    What really puzzles me is the HVAC. Why is wh/mi less for city than highway? If they HVAC output is set the same (maybe that's a bad assumption?) you'll use more energy per mile at lower speeds, but the chart shows the opposite.
     
  7. TEG

    TEG TMC Moderator

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    HVAC also used to cool the battery pack which otherwise gets hot during high power output?
     
  8. dpeilow

    dpeilow Moderator

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    Nice to see Martin's 2.8kW / 1 car slide in there. I aways like to drop that one on the skeptics.

    In the souyth of England it is closer to 3.6kW / 1 car but still totally doable.
     
  9. ggr

    ggr Roadster R80 537, SigS P85 29

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    My understanding is that the city cycle involves a fair amount of accelerating and braking. While you do recover energy through regeneration instead of braking, there is an unavoidable loss each time you do it. The absolute best mileage is when crawling along in traffic that's doing about 20 mph but doing it steadily.
     
  10. tdelta1000

    tdelta1000 Active Member

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    #10 tdelta1000, Dec 5, 2011
    Last edited: Dec 5, 2011
    http://iee.ucsb.edu/files/16Straubel.pdf
    The link provided more insight into the mad minds at Tesla Motors. I think TM has a really good grasp on its goals for the current product line and the futre offerings.

    BTW, thanks for sharing the link.... if only those guys across the pond would give credit where it's due. Sorry for the sidebar.:cool:
     
  11. VolkerP

    VolkerP EU Model S P-37

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    The "grid integration" aspect is just 1 slide... I hoped for more as I read into the presentation... :confused:

    Where is the TM wallbox with V2G uplink announcement?
     
  12. mpt

    mpt Electrics are back

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    Anyone have any comparative data on tire choice? I just swapped the rears for 225/45R-17 Michelin Primacy MX. They claim lower rolling resistance but what does that mean?
     
  13. Doug_G

    Doug_G Lead Moderator

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    It means they are very resistant to rolling.
     
  14. TEG

    TEG TMC Moderator

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    Huh? The opposite... They roll more easily. I don't know if either of you are joking.
    The stock Yokohama tires were considered low(ish) rolling resistance, so I don't know if the new ones would be any better.
    Rolling resistance contributes to wh/mi efficiency and maximum range per charge.
     
  15. Doug_G

    Doug_G Lead Moderator

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    For the record, let me state: :tongue:

    In all seriousness, I have compared long trip power consumption between Yokohama AD07 and Toyo T1R and didn't find any detectable difference. Purportedly the AD07 has low rolling resistance but the T1R's were just as good.
     
  16. William13

    William13 Member

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    I have been looking at tires recently and the difference between a manufacturer's standard tire and higher efficiency tire is less than one percent milage difference. This would not be easily measured by an individual. I am not sure that it should impact a individual's tire choice unless every thing else is equal.
     
  17. VolkerP

    VolkerP EU Model S P-37

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    There are already Roadster tire threads here and there so please don't turn this thread into another one.
     
  18. neroden

    neroden Happy Model S Owner

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    Here's the thing: low rolling resistance generally means poor traction, apart from minor tread design choices and whatnot. So the tire losses in that chart from Mr. Straubel are pretty much inevitable.

    Only way to really avoid that is to put the car on rails, but then it's a train :)
     

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