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Acceleration limiter, some charts from Pacific Raceways

Discussion in 'Model S: Driving Dynamics' started by brianman, Jun 29, 2014.

  1. brianman

    brianman Burrito Founder

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    The first session was very light. Many of us were new to the track, and we only had a few green laps at the end. The limiter wasn't an issue because we weren't really at speed much.
    PacificChart1.png

    In session 2, you can see it easily 2/3rd into the session.
    PacificChart2.png

    In session 3, halfway in.
    PacificChart3.png

    In session 4, about 1/3rd into the session.
    PacificChart4.png


    For those with small form factor devices, hopefully the image scaling makes this page viewable without drama. I just got a new monitor and, believe it or not, these are scaled down (roughly 2:1) from what I was actually charting in Excel. :)
     
  2. zwede

    zwede 2013 P85+

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    Even limited you still have twice the power of a Nissan Leaf. :)
     
  3. Alysashley79

    Alysashley79 Member

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    @brianman. We've been wanting to take our MS out on pacific raceways but haven't gotten our "license" there yet. Can I ask how long were you able to maintain top speed? I know that the limiter kicks in but on a straight road and not racing I've been able to go about 3 miles before I've been forced to back off due to lack of road (have our own private driveway) I'd love to be able to take the MS out there and look forward to it soon.
     
  4. brianman

    brianman Burrito Founder

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    #4 brianman, Jun 29, 2014
    Last edited: Jun 30, 2014
    Well, strictly speaking "top speed" is 133mph and I didn't reach that.

    Getting up to 90+ on the straight reliably was easy even with the limiter (assuming no driver errors and no traffic in the way). Dunno if that answers your question....
     
  5. brianman

    brianman Burrito Founder

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    #5 brianman, Jun 12, 2015
    Last edited: Jun 12, 2015
    I'm not sure if I have the time or energy to build the charts again, but I can confirm that you can reach multiple limiters on the P85D even with > 100 rated miles left. Today I saw limiters at 240 kW, ~160 kW, and 120 kW -- all of them with > 100 rated miles remaining. The 120kW limiter is painful on a P85D.

    Highest power was 396 kW @ 87% SOC @ 63mph.

    Here's a quick and dirty chart for session 3:
    Pacific15_Power_Session3.png
     
  6. p85dk

    p85dk Member

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    Are driving with or without regen on?
     
  7. AWDtsla

    AWDtsla Active Member

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    Judging by the graph it's set to low.
     
  8. Vger

    Vger Active Member

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    Really interesting data. Thanks for collecting and posting.

    I do wish we new more about the constraints involved, like we do on the Roadster. I noticed recently a firmware upgrade to the Roadster I belatedly got last year now shows the actual temperatures of the motor, PEM, and battery (ESS) on the VDS. It would be nice to know that for the Model S.
     
  9. kirkbauer

    kirkbauer Member

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    I'm new to the P85D but have one on order. I'd love to know more info on acceleration limitations. Are you guys saying that the charge level of the batteries affects the acceleration performance?
     
  10. djp

    djp Roadster 2.0 VIN939

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    That's not a firmware update, your ranger must have left the alert messages in debug mode on your last service visit. Agreed it would be great to have the same data for the Model S, plus log files!

    Yes, as the battery voltage drops it takes more current to produce the same amount of power. The car limits the acceleration at lower states of charge to protect the battery pack.
     
  11. kirkbauer

    kirkbauer Member

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    I'd heard that but didn't know for sure. What is the minimum percentage charge you need to get maximum performance?
     
  12. djp

    djp Roadster 2.0 VIN939

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    Ha - that's what we're trying to figure out in this thread! There are other factors that limit power, for example temperatures of the motor and pack, so it's not a straight-forward question. Generally the higher the voltage the better for performance, but charging to a high state of charge is also hard on the battery.
     
  13. brianman

    brianman Burrito Founder

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    Correct.
     

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