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Miles past 0/power restriction

Discussion in 'Model S: Battery & Charging' started by Brass Guy, Jul 14, 2016.

  1. Brass Guy

    Brass Guy Member

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    I'm on a cross country road trip. The last time I recall going towards the bottom of the battery, I got a power restriction of about 160kW at 30 rated miles remaining. I just arrived at a supercharger with 14 remaining, and no dotted yellow line. I was a little disappointed that my 100% this morning was 246 (classic 85), but now I bet I have between 20 and 30 miles past zero; so maybe no actual range loss after nearly 3 years/70k miles...

    How's my logic hold up?
     
  2. kort677

    kort677 Active Member

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    I still have never seen any sort of power restriction while driving on the bottom of the battery. I just returned from a trip and had the battery down to under 10 miles and under 12 miles. while I do not drive the car hard 65 to 70 mph to "limp" into the SpC, on another trip I actually got down to the charge now warning a mile out from the SpC, I didn't see any sort of notice or actual speed restriction. My advice would be to plan well and heed the warnings from the trip planner to reduce speed en route in order to make your destination.
     
  3. SmartElectric

    SmartElectric Active Member

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    Classic 85 here with "A" battery. I've found it easy to reproduce : to get the dotted yellow line in the summer, just floor it when lower than 15% SOC. I've seen the dotted line move slowly from near 300 kW and then gradually drop to 160 kW if I floor it for 10 seconds when SOC is under 20%. The dotted yellow line can also disappear if you are near 20% SOC, floor it for more than 10 seconds, line appears, then let off and the line eventually goes away.

    Even easier in the winter, just turn the car on in -10C and the dotted yellow line is visible for at least 10 minutes while driving initially, regardless of how long I preheat.
     
  4. David99

    David99 Active Member

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    The limiter sometimes comes earlier or sometimes later. It depends a lot of the temperature and your driving style. Not sure you can assume not seeing the limiter means you can go way passed zero miles. The chances are probably better than when the limiter is showing up.
     
  5. kort677

    kort677 Active Member

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    I guess my style of driving isn't as aggressive as some others might drive, when I am running down my SOC trying to get to the SpC with something in the tank I am not flooring the car.
     
  6. Brass Guy

    Brass Guy Member

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    When I saw it on low battery, it was summertime and I was not flooring it at all since I was conserving energy. Also there's a video on youtube where a guy shows his dash as the car is about to shut down, and it shows a power limit dropping so low the car cannot speed up from 20.
    I am not planning on testing my theory anytime soon though.
     
  7. Max*

    Max* Autopilot != Autonomous

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    I wouldn't try this. There's been a lot of debate if there's a buffer below 0, and I believe the consensus is no there isn't. If you're able to drive below zero, it's just the algorithms weren't calibrated correctly, and you might be able to drive 1 mile below zero or 30 miles below zero, but it would sure suck to be stuck 29 miles from a SpC thinking you could've made it below 0.
     
    • Informative x 1
  8. Brass Guy

    Brass Guy Member

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    Max* - that's exactly what I'm suggesting; the algorithm is probably that far off on mine. The combination of 146 @100% and no power restriction at 15.

    If I get bold, maybe I'll see when "charge now" appears.
     
    • Like x 1
  9. David99

    David99 Active Member

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    There actually is proof that there is a buffer to protect the battery at the low end. When the battery is showing 0% and 0 miles it has about 4-5% left.

    In the photo below you can see. At the top is my iPad showing the true percentage coming from the CAN bus. At the bottom is what Tesla shows the driver.

    Some have gotten 15 miles passed zero, other had their car shut down right at zero.

    buffer.jpg
     
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  10. Max*

    Max* Autopilot != Autonomous

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    I'm not saying there isn't an anti-bricking buffer.

    I'm saying there isn't some hidden reserve an average person can get to, once you hit 0 miles, that all of a sudden ta-da, you can now use an additional 30 miles of range.

    From what I read/know/understand, and I'm not an expert in this field, is that it's just due to calibration issues. Not due to having a guaranteed 30 mile buffer below 0 miles.
     
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  11. David99

    David99 Active Member

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    I doubt it's calibration issues. 15 miles or more would be a massive calibration issue which is unlikely. Especially since Tesla said that while the calculated remaining range can be a little off, especially when someone charges partially often, it does get more accurate once you reach the lower charge levels as the data from the battery gives you an accurate idea what the remaining state of charge is. So I doubt the calibration is off so much that some can go 20 miles passed zero whiles others shut off right at zero.

    Tesla might allow the car to use some of the protection buffer when you are headed for a charging station (knowing you will plug in and no damage will be done). I don't know. We can all just speculate.
     
  12. kort677

    kort677 Active Member

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    are you saying that the car's systems are so advanced that the car will know that you are headed towards a SpC? or any other charger?

    how about if you're 30 miles away from one with only 10 miles of rated range?
     
  13. MP3Mike

    MP3Mike Active Member

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    I highly doubt that. Don't we have one person that reported their car stopped right about at 0 and he was just 2 miles from a SpC...
     
  14. David99

    David99 Active Member

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    Having a charging station as destination in the navigation doesn't need much sophistication :)
     
  15. SmartElectric

    SmartElectric Active Member

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    #15 SmartElectric, Jul 18, 2016
    Last edited: Jul 18, 2016
    Tesla navigation advises the speed necessary to reach a destination if the distance is greater than the rate range available.
    See this recent (yesterday) video from Tesla Bjorn:
    Seek to 11:32 within the below video


    Or paste this in browser without the "CUTMEOUT"
    CUTMEOUThttps://youtu.be/NCu60eu1Y0Q?t=692
     
  16. David99

    David99 Active Member

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    Yes and he was going fast up a hill pushing it hard. Did he have his navigation set for the Supercharger?
     

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