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Slider for charge percentage not accurate?

Discussion in 'Model 3: Battery & Charging' started by lanbo, Dec 30, 2019.

  1. lanbo

    lanbo Member

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    There are a bunch of people that charge to 80% or 90% and then project their total range at 100%.

    Well, I've found out the grid lines in the display are not set to 60%, 70%, 80% or 90%. At least in my car.
    Could you check in yours?

    These lines are clearly set at 61%, 71%, 81% and 91% in my car.

    You can test it in different ways.

    The easiest way is to set the car to 90% using the App. The grid lines in the App are not distorted.

    So, set the car to 90% in the App and then check in the car where is the charging line.
    You may see it's well above the 90% grid line as in my car.

    You can also test it by setting the car to charge to 80 or 90% (in the car's display) and then set the display to %.
    I always get 81% or 91% when the charging finishes instead of the 80% or 90%.

    Is this a normal behaviour shared by all cars or only by a subset?
     
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  2. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    We should start a petition.
     
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  3. DrtyJrze

    DrtyJrze Member

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    Yea...no.

    I set to 80% and it charges to 80%.

    Are we really down to this level of conspiracy theories?
     
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  4. lanbo

    lanbo Member

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    I have described a fact that can be easily tested.
    I set it to 80% and charges to 81%.
    I set the car to 80% in the App and then go check where is the charging line in the App and it's under 80%.
     
    • Disagree x 1
  5. J1mbo

    J1mbo Active Member

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    Wow, that is a dirty trick! 1% of battery charge sneakily hidden away by the UI. /s
     
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  6. webbah

    webbah Member

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    90% is 90% for me whether I set it in the app or the car. No issues at all.
     
  7. lanbo

    lanbo Member

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    Let me EDIT the first post.

    When setting in the App to 70% or 80% you can see it is set BELOW 70% or 80% in the car display.

    Could you just check?

    Does not happen with 90%.
     
  8. lanbo

    lanbo Member

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    Yeah. It only happens with 60, 70 or 80%. Cannot edit the first post.
     
  9. timk225

    timk225 Active Member

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    Instead of having a slider bar to set the charge limit at 80% or 90% or whatever, there should be actual numbers, and an up or down arrow beside them to change the numbers. Easy solution.
     
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  10. 640k

    640k Member

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    so i'm going to go out on a limb here and maybe even talk a little bit out of my ass but here goes...

    an educational guess as to what is "actually" happening involves some math that are not visible to you and me. the "drawing" of the gauge percentage is a poor representation of a limiting factor set within constraints of the battery.

    here's why i say this:
    you cannot think of the battery as a container. it is not some magical can used to store a finite amount of electricity that is then passed on to a motor for consumption. all batteries rely on a chemical reaction that passes electrons from one source to another. the chemical process within the battery is what returns the electricity for use.

    what this means is, while we can accurately rate the amount of energy (electricity) being transferred IN TO a battery, the chemical reaction to extract that energy is not a 1:1 product and there are losses and inefficiencies that take place. what this means is we need to use a little bit of math to determine how much remaining energy is left and attempt to represent it on a screen for us to understand.

    the long of the short of it is, it's not a perfect science. we can't just look at the measurements of a cup and know exactly how much energy is left.

    does anyone remember when AA batteries used to have those strips on the side that when you push the + and -, it would tell you how "full" your battery was?

     
  11. TydalForce

    TydalForce Member

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    Looking at this just made my thumbs hurt lol
     
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  12. raptor5244

    raptor5244 Member

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    This is an outrage!
     
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  13. antoinearnau

    antoinearnau Active Member

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    When I set 90% on the app, it charges to 89%...
     
  14. tomas

    tomas Out of warranty...

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    The lengths people will go to to avoid happiness....
     
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  15. go2realize

    go2realize Member

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    I observed this when the ambient temperature falls below 30F. When charging from 50% to 80% using the app, the scroll bar when it hits the grid bar it shows 79%, but as the car start charging it recovers to 80%, but towards the end of the charging session it shows 81%. In addition to this, there is also a 1% discrepancy between what was shown on the battery indicator (both the app and the car) and the data pulled through external data logging software (in my case Teslamate). I think there are several factors (temperature, rounding errors, other unknown) affecting the values shown in the battery indicator. I think reverse engineering to understand the exact math behind it is not going to be accurate. I don't think there is any conspiracy.
     
  16. lanbo

    lanbo Member

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    #16 lanbo, Dec 30, 2019
    Last edited: Dec 30, 2019
    Che
    Chemistry is the same for the App and for the car display. What I'm saying is that the 80% on the car is not the same as the 80% on the App.
     
  17. lanbo

    lanbo Member

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    You chose to reply to this post instead of setting the app to 80% and then check on the car display. It's better to not know I guess. In fact, ignorance is a possible way to be happy. Good for you ;)
     
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  18. lanbo

    lanbo Member

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    Yeah, I used the conspiracy theory to get some attention to the post I must admit. Many fellow posters fell for it. I'm sorry. :)
    So, yeah. It's not only me. There's some discrepancy on the readings of the car's display and the reality.
     
  19. go2realize

    go2realize Member

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    • Like x 1
  20. hydro 481

    hydro 481 Active Member

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    That thread title is a bit harsh don’t you think?
     

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