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Lowest Voltage after going 9 miles below 0

Discussion in 'Model S: Battery & Charging' started by David99, Jul 5, 2014.

  1. David99

    David99 Active Member

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    Trust me, I had no intention to do that, but a few days ago I had to go 9 miles after the battery shows 0 miles.

    When I plugged in it showed a Voltage of 291. It shot up to 350 as soon as the Charger started.
     
  2. Hodginator

    Hodginator Member

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    That must have been a scary 9 miles...
     
  3. CalDreamin

    CalDreamin Member

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    Do you have a 60 or an 85?
     
  4. David99

    David99 Active Member

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    I have an 85. I charged enough to make it easily based on the same trip I did a few days before where I actually drove pretty fast. But this time I got bad head wind and that killed me. I ended up going really slow drafting behind a semi and still arrived with 9 miles below zero. Yes it's a pretty scary experience. I expected the car to shut down and be stuck any time :( The power limiter was down to 85 kW.
     
  5. TonyWilliams

    TonyWilliams Active Member

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    I've had a Nissan LEAF down to about 295 volts, and the voltage drops like a rock from about 350 volts. If any one cell pair drops below whatever the individual cell cutoff voltage, the car can stop well above 295 volts.

    Max on the LEAF is 395 volts.
     
  6. David99

    David99 Active Member

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    I think the highest on the S85 is 405. Probably depends a little on the temperature.
     
  7. CalDreamin

    CalDreamin Member

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    Interesting. I wonder if anyone has an idea what this power limitation is as a function of usable miles remaining (as opposed to the miles remaining estimates the car makes which aren't very accurate at a low SOC).
     
  8. HankLloydRight

    HankLloydRight Fluxing

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    So the voltage up initial plug in is the pack voltage and not the charger voltage? Or, how does one read the pack voltage?
     
  9. islandbayy

    islandbayy Active Member

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    For starters, that's how lithium works, maintains steady vtage until the very end then drops like a rock.
    Ive had my 60kW pack down to 263ish volts this past winter.
     
  10. David99

    David99 Active Member

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    It is a safety feature to prevent the cell voltage to drop below a certain voltage which would be damaging. The higher the load, the lower the voltage drops. As the state of charge drops the voltage drops. If you now draw a lot of power from the battery the voltage drops even lower. Other factors can influence it as well that's why the power limiter doesn't come on at the same state of charge each time.

    The S60 and S85 have a different system voltage so they can't be compared by just looking at the number.

    - - - Updated - - -

    What's the highest on the 60 when finished charging?
     
  11. islandbayy

    islandbayy Active Member

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    353 volts on my 60kW A pack
     
  12. dave

    dave Member

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    How do you tell your battery voltage?
     
  13. David99

    David99 Active Member

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    It only shows when plugged in on a Supercharger. When plugged in into a normal AC charger, it will show the incoming voltage on the AC side, not the actual pack voltage. On a Supercharger, the AC chargers are bypassed and is directly connected to the battery, thus you see the true battery voltage.
     
  14. dave

    dave Member

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    Ahh, thanks. Still waiting to get Superchargers in my neck of the woods!
     
  15. guakankan

    guakankan New Member

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    Supercharge or at home?
     
  16. apacheguy

    apacheguy Sig 255, VIN 320

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    So is it safe to assume that we can use the dashed limiter line as an indication of when the car will truly power down? In other words, will all S85s make it down to the same 85 kW limitation before coasting to the side of the road?

    I've been down in the teens before and just a couple of times in single digit territory, but have never seen the limiter go that low. But now that Tesla hides % SOC below 0 miles, I guess we can use this measure instead.
     

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