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Charging stops at different mileage

Discussion in 'Model S' started by whitecotton, Jan 14, 2016.

  1. whitecotton

    whitecotton Member

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    Houston, Texas
    Is it normal for the charging to stop at different mileages? The night I got 7.1 it stops at 172 instead of 174 and tonight it stopped at 171 although I haven't changed the slider bar on the charging menu. Are some of the cells going bad? Should I call service? I may be overreacting but when the battery habits starts changing it makes me a little nervous.
     
  2. msnow

    msnow Active Member

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    It stops a the percentage you set it for so yes if it's dropping rapidly (eg a mile a week) you should report it. It's probably a software issue and not a problem with the battery but best to have them check.
     
  3. AndyM

    AndyM Member

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    I wouldn't worry about one mile or two. Sometimes the rated range calculation is different based on the pattern of usage of the last discharge cycle. My rated range gets less and less over time without going on a long trip and deep discharge. then it rebounds to the number I'm used to seeing. I have also seen software updates change the calculation formula of rated range.
     
  4. apacheguy

    apacheguy Sig 255, VIN 320

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    Yeah, 7.1 shifted me down a couple miles too. It's likely just due to them messing with the algo.
     
  5. .andrew

    .andrew Member

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    I've noticed that the rated range tends to fluctuate based on my previous day's driving efficiency.

    i have been paying closer attention to my Wh/m number and the lower I get it, the higher the rated range is the next morning after it finishes charging.

    I recently picked up a P90DL and with an 80 mile round trip commute I've been averaging between 313-340 Wh/m which has resulted in 90% rated ranges of 227-232 miles.
     
  6. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    There are a number of factors. This time of year it's generally due to the colder temperatures. The car is still stopping at the same point -- it's just measured by the battery's state of charge (90%) instead of the number of rated miles (which is calculated from a bunch of parameters). If you set the car to battery % readings, you'll see that it stops at the same point every time you charge.

    On the other hand, the rated range does not fluctuate based on driving efficiency - it's not a factor taken into consideration. I've looked over my data and I did some preliminary calculations, and it's not bearing out. See Displayed Range and Seasonality for more information.
     
  7. msnow

    msnow Active Member

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    According to Tesla, there are other "use cases" that account for a miscalculation of the rated range such as how the battery is discharged. I don't know what the other use cases they were talking about are nor do I know for a fact if this true or even just an issue with the 90 battery pack. I think you have agreed with that assessment recently.
     
  8. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Yes, although those fluctuations are more long-term than short-term and they're applicable to other battery packs as well. Over a long period of time, if you never take the battery below 40% (100 miles or so), the car can lose track of where the "bottom" of the battery might be. Then, the first time you drive it down to 20-30 miles or so and charge back up, you find a different rated range.

    The 90 kWh packs seem to have something else going on that hasn't been figured out yet. I hope they do get it figured out soon and the range returns to something more reasonable. Once my Model X is delivered, I'll begin collecting data on it to track what it looks like.
     
  9. TexasEV

    TexasEV Active Member

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    Yes you are overreacting.
    Two point to understand:
    1. The rated range is an estimate based on an estimate of battery state of charge. It can't be measured directly. Don't take it too literally.
    2. Rated range changes with temperature, when it's colder you will see a little less rated range.
     
  10. Kalud

    Kalud Member

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    Also toggling Range Mode ON/OFF slightly changes the displayed range at the end of a charge. You're displayed range will be slightly higher when Range Mode is ON.
     

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