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Failed range calculation left me stranded

Discussion in 'Model S: Battery & Charging' started by Twiddler, May 17, 2018.

  1. wwu123

    wwu123 Member

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    #61 wwu123, May 27, 2018
    Last edited: May 27, 2018
    Based on the latest Model 3 hypermiling run last night, seems like there was about 5 kwh hidden reserve on that particular car - so about 20 miles at normal driving speeds, on a fairly new Model 3. This was the usable hidden capacity, there is also additional non-usable hidden charge even below that to protect the battery from fully discharging and really damaging itself.

    But basically the usable hidden capacity is there to ensure that even the outlier cars are still able to drive to indicated 0% charge/0% range, as the car ages and low SoC becomes harder to measure...
     
  2. Testwa

    Testwa Member

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    While I also wish there would a more accurate estimation, people like you are the reason why some car makers play it safe like Mercedes and avoid to get sued: once you get below 50km of range (on an ICE) they show just "---km" instead of remaining km's in the dashboard. That is also an very annoying approach because when you need it most it doesn't show anything, how useful is that?
    Problem with batteries is to identify the 0% as well as the 100% over and over again which is even more difficult to get accurate if the battery is always operated e.g. between 10 and 90% and not between 0 and 100%.
    So hopefully Tesla can improve their estimation and their warning in the future.
     
  3. Rocky_H

    Rocky_H Well-Known Member

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    Hmm, unfortunate that Musk is not up to date on how all of their cars are and is saying that. The Model 3s may be set up differently with holding some driving reserve in there.
     
  4. Uncle Paul

    Uncle Paul Well-Known Member

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    The Tesla has an algorithm that predicts remaining range depending on previous driving analysis.

    If you were driving your borrowed car it was making predictions from the previous driver.

    If you drove more agressively than your Dad, then it would not accurately predict your range with great precision.

    Sometimes people that are embarrassed will blame the car, when the fault is really theirs.

    Common practice with all vehicles is to have a reasonable buffer to assure getting to your final destination. Trying to push it often gets you burned.

    AAA provides 50,000 service calls a year to their members who run their vehicles out of gas.

    Reminds me of that Seinfeld episode where Kramer gets a rush by seeing just how far below E they can push the car on a demo ride.

    Airline pilots are some of the best trained in the world. Their planes have some of the most sophisticated electronics also, however they would never carry enough fuel to "just make it" They always insist on enough for a substantial margin of error.
     
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  5. TexasEV

    TexasEV Well-Known Member

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    NO NO NO. How many times do people here have to explain that rated range has nothing to do with your driving? The range displayed on the battery meter is EPA rated range. Period. Full stop. It has nothing to do with your driving style or that of a pervious owner.
     
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  6. Chaserr

    Chaserr Hyperactive Hyperdrive

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    I wish the battery gauge had another option for "calculated" that actually does base its estimate on your driving. The data is there in the nav and energy apps, but right now the instrument cluster battery will never update to show better or worse range based on how you drive and only bases its number on the current percentage of ideal or EPA ratings.
     
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  7. David99

    David99 Active Member

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    As you said, the range based on driving style is available in the energy graph. So basically you just don't like to look at your main screen? :)
     
  8. Chaserr

    Chaserr Hyperactive Hyperdrive

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    You can bring up an accurate range screen if you don't want to have your normal screens up instead, but since the data is already available and range is always displayed in the IC, it would be more appropriate to say I don't like looking at falsified data on my instrument cluster when I know there is accurate data intentionally not being displayed in that exact place.

    The car doesn't have to lie to you, but it does unless you change it to %. It's perfectly able to display accurate range next to the green battery bar and not doing so was a strange UI decision someone made.
     
  9. Olds442

    Olds442 Member

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    good info, thanks for posting.

    i keep my car over 10% because i hate walking.
     
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  10. David99

    David99 Active Member

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    The car doesn't lie. The car shows a range that is based on a more or less realistic test cycle. That's not a lie. The energy graph shows the energy used per distance accurately, but it also considered elevation change, road conditions, wind and driving speed. These things might be different in the upcoming miles so it's not more accurate unless all those variables are exactly the same.
    The best guess is the trip graph. It knows at least elevation of the upcoming miles. I tend to use that for range estimates.
     
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  11. TexasEV

    TexasEV Well-Known Member

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    I disagree that your past usage is a more “accurate” range. How you drove for the past 15 or 30 miles may have nothing to do with how you drive for the next segment. You could be going from highway to local roads or vice versa, terrain could change, there could be a traffic jam, etc. As Yogi Berra said, prediction is difficult, especially about the future. With EPA rated range at least it’s a constant, and you come to know if your driving at any given time is likely to be at that range, or more, or less. If the displayed range always meant something different, depending on recent driving, it would be harder to interpret any number that’s shown.
     
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  12. dhrivnak

    dhrivnak Active Member

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    Unfortunately it happened to me in my Roadster as I thought I had 20 miles left when the car decided otherwise. It was my first long trip with the 3.0 battery so maybe things were not calibrated for the car.
     
  13. PhaseWhite

    PhaseWhite Member

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    An EV is fundamentally different from a gas car, driving a gas car down to empty will not put increased wear on the engine. Doing this in an EV will impact the battery. I would never drive my car down to <10% of battery unless absolutely necessary. Why did you need to do this?
     
  14. David99

    David99 Active Member

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    It is fine to drive down to zero as zero is not really zero in a Tesla :)


    Elon Musk on Twitter
     

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  15. PhaseWhite

    PhaseWhite Member

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    I'm sure it's fine, my point is it's just not good for the battery and should be avoided unless needed. Just because it won't break it doesn't mean you should doit when you have better options like charging it up again.

    I believe you are aware of this but just incase:
    http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

    Table 2 estimates the number of discharge/charge cycles Li-ion can deliver at various DoD levels before the battery capacity drops to 70 percent. DoD constitutes a full charge followed by a discharge to the indicated state-of-charge (SoC) level in the table.


    Table 2: Cycle life as a function of
    depth of discharge.* A partial discharge reduces stress and prolongs battery life, so does a partial charge. Elevated temperature and high currents also affect cycle life.

    Note: 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.

    100% DoD ~300 / 600
    80% DoD ~400 / 900
    60% DoD ~600 / 1,500
    40% DoD ~1,000 / 3,000
    20% DoD ~2,000 / 9,000
    10% DoD ~6,000 / 15,000
     
  16. Uncle Paul

    Uncle Paul Well-Known Member

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    "NO NO NO. How many times do people here have to explain that rated range has nothing to do with your driving? The range displayed on the battery meter is EPA rated range. Period. Full stop. It has nothing to do with your driving style or that of a pervious owner."

    Help me with this. I charged up to what the computer suggested to get me to the next Supercharger. I started driving 90 MPH and in a little while the computer told me to slow down to 50 mph to make the scheduled stop. Does it not mean that my rated range was being recalibrated due to me driving fast.
     
  17. TexasEV

    TexasEV Well-Known Member

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    No. You’re referring to the “predicted range” on the energy app when you are using navigation. This is not the rated range which is what the battery meter always displays.
     
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  18. lklundin

    lklundin Active Member

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    I believe a driver should familiarize themselves with their vehicle.

    So I have (once) driven my ICE with a 90 l tank to a gas station (very close to home) and filled it with 89.5 l of fuel (the indicated range goes to zero with 5 l of fuel left, so one has to monitor the consumption closely after that).

    Similarly, I have (once) circled a Model S P85 around a charger until its range was zero.

    That way I experience no range anxiety during normal driving, where I stay within more conservative margins. Admittedly, it does unsettle some passengers when the range goes to zero and there is still e.g. 30 km to the next couple of gas stations.
     
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  19. cwerdna

    cwerdna Active Member

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    The --- behavior is what Nissan does on Leaf. The guess-o-meter turns to --- miles at the 2nd warning (VLBW aka Very Low Battery Warning). '13+ Leafs finally got a % state of charge display and at some point after GOM has turned to --- miles, the % SoC display can turn from some value like 6 or 7% to ---%. I have firsthand experience with this.

    One needs to use tools like Leaf Spy to have visibility once you're into ---%.
     
  20. No2DinosaurFuel

    No2DinosaurFuel Active Member

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    I am sure I will get a lot of disagree by saying this, but I'm going to say it anyways. I understand the range on the Tesla is an estimate, but 6 miles should be comforting enough to get 2 miles out of assuming the driver is not speeding and doing high speed accelerations. I also understand it's hard to estimate the range left, but tesla should do a couple of things in situation where it has less than 5% of what it thinks it has left. They should make the car super sluggish during acceleration. Yes it can be a safety issue, but definitely auto put it in chill mode for sure. And prioritize regen.

    The lowest I gotten mine to is 12 miles, but that was when the car was relatively new. I guess going forward, I will need to be more weary of the range estimate as my Tesla ages.
     

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