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Slider for charge percentage not accurate?

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?
 
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?

 

raptor5244

Active Member
May 10, 2019
1,585
1,280
Florida
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?


This is an outrage!
 
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.
 
Che
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?


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.
 
Last edited:
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.

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.
 

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