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Discharging at High Speed (>100 mph)

Discussion in 'Model S: Battery & Charging' started by horst98, Jun 29, 2014.

  1. horst98

    horst98 Member

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    #1 horst98, Jun 29, 2014
    Last edited: Jun 29, 2014
    I am living in Germany and have a normal Model S 85kWh. We use km/h instead of mph in Germany. Please note, that 1 mile equals 1,609 kilometers.

    I waited months for a perfect time to drive my fully topped up battery empty at a very high velocity. There are no speed limits on German Autobahns.
    Yesterday (Saturday 5:30am) was the perfect time. My requirements for such a day were:

    1. Low traffic density
    2. Dry Roads
    3. Daylight
    4. Temperature < 20°C (68F)

    I started topping up the car at 3:30am. 100% was reached at 5:00am and I started at 5:35am. I wanted to race the car as fast as possible in safe conditions. These conditions were:

    0. Safety! No illegal speeds or maneuvers. Keep safety distance (for 200km/h - 125mph: 100m - 110yrds)
    1. Reach my destination.
    2. Long term power consumption <= 80kW
    (I wanted to lower the risk for the battery. Long term discharge current should be less than 1C)
    3. Driving foresight-fully not braking too often.
    (I had to slow down twice from ~160km/h (100mph) to 120km/h (75mph) using the breakes)
    4. After reaching 100km (60mls) Typical Range, I reduce max. power to ~60kW
    (Cell voltage will have reduced significantly then and the taken amps from the battery would otherwise rise above 1C)

    The Results:
    total.jpg
    Average speed had been ~165km/h (102mph).
    Average energy use was 410 to 430 Wh/km (660 to 700 Wh/mi) on the Autobahn.
    With street works, few speed limits and change at Autobahn crossings the average energy consumption was 392 Wh/km (631 Wh/mi).

    I reached a distance of 181,6km (112,8mi).

    Very interesting was the amount of energy I was able to get out of the battery. 0 Typical Range was reached 100m (90yrds) in front of the garage. So the Zero Mile protection as well as the Block Protection were untouched. 71,2 kWh came out of the battery. With these 9 kWh protection the battery just gave 80,2 kWh (instead of 85 kWh).

    This is normal, because Peukert's Law says, that higher currents result in more losses. I compared this high speed discharging with a typical discharging of mine at an average of 204 Wh/km (328 Wh/mi). I got more (74,3 kWh) out of the battery during slow discharging. I also calculated the Kapa of the Peukert Function. It resulted in a value between 1.03 and 1.04, which is significantly better than a standard Li-Ion battery (1.05). This shows the high end chemistry of the cells in our cars.

    P.S.: Cruising along undisturbed at 200km/h (125mph) I was overtaken by a Nissan GT-R at roughly 300km/h (185mph). There are more maniacs under their ways on German Autobahns very early on weekend mornings :scared:
     

    Attached Files:

  2. GSP

    GSP Member

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    Thanks for the post. Very informative and interesting.

    Enjoy your Tesla! :big grin:

    GSP
     
  3. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Such a great post! Well done and real world data like this is golden. Getting 180 km under conditions like that is very good IMO, much better than Tesla's own speed vs. range graph predicts.
     
  4. yobigd20

    yobigd20 Well-Known Member

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    These results seem accurate. I've done 100+ mph on cruise control for 100 miles (I won't say where haha bc we dont have autobahns) and sustained >550Wh/mi. basically you'll get 35-45% range for these speeds. a full 265 will barely reach you a little over 100 miles at these speeds. that being said, I'd like to see someone try this in a Leaf or any other EV. I bought the MS over any other EV simply because you can still get decent range without having to worry about what speed your driving.
     
  5. mibaro2

    mibaro2 Member

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    Wow.
    Thanks for the informative post.
    One of these days I'll drive on the autobahn.
    Nice to see safety was at the top of your list.
     
  6. horst98

    horst98 Member

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    The Germanistik car rental company Sixt starts renting Model S real soon now.
     
  7. Realist

    Realist Member

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    180km range is nothing and that is just the main weakness of the Model S.

    At that speed and under these conditions with almost zero traffic any standard BMW 5 or Audi A6 gives you 500-1000km.

    And it is a lot faster.
     
  8. David99

    David99 Active Member

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    Interesting to see the amount of energy you were able to get our of the battery reaching 0. Your test could be considered "worst case". 71.2 kWh is pretty good. My record when driving an average of 60 mph / 96 km/h was 76.5 kWh reaching zero (total drive time was about 4 hours). The difference is only 7% at almost 4 times the load. Excellent batteries indeed.
     
  9. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    That's all true...and completely beside the point.
     
  10. widodh

    widodh Model S R231 EU

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    Keep in mind that every EV will suffer serious range degradation when speed goes up. We call that the laws of physics.
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Audi A6 3.0 TDI (comparable) has 55 mpg tested, that's 0,51 L/10 km. In similar conditions Model S got 265 miles or 430 km.

    The A6 has a tank volume of 19.2 Gls which is 73 literes. So EPA tested range would be around 1400 km.

    The S at 165 km/h average got 180 km which is 42% of 430 km.

    What does the 3.0 liter Audi A6 get in MPG or L/10 km when going steady at 165 km/h??? Can't finds this info online. I do believe its range does not decrease to only 42%....
     
  12. CalDreamin

    CalDreamin Member

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    #12 CalDreamin, Jun 30, 2014
    Last edited: Jun 30, 2014
    The Audi A6 TDI 3.0 is EPA rated for 29 mpg, not 55 mpg.

    All cars have substantially lower efficiency at high speed. While test data for the Audi A6 TDI is not included here, mpg as a function of speed for a similar BMW diesel 5 series and a VW TDI are included.
     
  13. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Sorry for incorrect numbers. The 55 mpg is for the far less powerful 2.0. Thanks for the correction.

    My own experience from a 2.5 litre Volvo turbo diesel is that while mpg drops with higher speed it doesn't drop as much as I've experienced with my Model S. This is because the electric driverrain is very efficient at all speeds while the ICE is relatively less efficient at lower speeds.
     
  14. Realist

    Realist Member

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    Going 160kph is not really an issue, but decelarating and accelerating is. You are using a lot more energy, obviously.

    Under such conditions the Model S range will drop further, below 100km eventually. It's not difficult to see why since 85kwh is not more than the equivalent of 8l gas more or less.

    An Audi A6 V6 TDI will always give you more than 600km range even under extreme conditions regardless the MPG figures. The only petrol car I know with a similar pathetic range like the Tesla is a Lotus Exige with horrible mpg and a very small tank. But I can still refill in less than 10 minutes at any gas station.
     
  15. tliving

    tliving Member

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    Very cool, would love to take my Model S on the autobahn. Last time I drove the autobahn was in a a crappy rental VW Golf. It was dangerous to drive that car on the road since it wouldn't go fast enough. I did enjoy the ausfahrt and einfahrt signs :)
     
  16. tomas

    tomas Traded in 9 rep bars for M3, used to be somebody!

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    1000 km @ 150+kph. You must have some weed mixed in with the fuel. Even 500, no. True high speed vs range is choice in tesla, but it has so many other positives... Which is why so many are buying it over bmw, mb, Audi.
     
  17. hiroshiy

    hiroshiy Active Member

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    My 90liter tank car with 4 liter NA engine runs about 400km per full tank of gas at @150km/h average.
     
  18. widodh

    widodh Model S R231 EU

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    And that's all it is.
    So you have 900kWh of energy in your tank and that gets you 400km.

    That's 2250Wh/km (3600Wh/mile)! Even at 150km/h a Model S still does about 280Wh/km, that's almost 8 times more efficient.

    So yes, ICE cars can run at higher speeds for a longer period of time, but that's because they are so darn inefficient!
     
  19. Johan

    Johan Took a TSLA bear test. Came back negative.

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    True.

    False.
     
  20. Realist

    Realist Member

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    The Audi A6 V6 TDI has a 75l tank. 600km range equals average fuel consumption at app. 12l/100km.

    You will not get that even if you push like a maniac. In fact, real range is close to 1000km.
     

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