Calculating Your Battery's Estimated Capacity Using the Car's Energy Screen

[jjrandorin]

Re posting here and making this a sticky post so it doesnt get lost. @AlanSubie4Life originally posted:

===========================================
(originally posted by @AlanSubie4Life. Original thread this appeared in can be found here: ( 2021 model Y scan my Tesla battery size)

.............

There is. Assuming the car is delivered at a decent SoC (above 80%):

Switch to Car -> Display -> Energy Display Mode => Energy

Then go to ^ -> Energy->Consumption screen, select "5 mile, average" and calculate:

Battery Capacity @ 100% (in Wh) = Avg Wh/mi * Projected Range / SoC%

If the data is not complete due to not enough miles, not sure what will happen, so car has to have 5 miles, maybe.

That will always give you your true battery capacity at 100%, within about 1kWh. ........


Caveat 1: Can't emphasize enough that you have to do this assessment at a decent charge level (otherwise massive rounding error will cause errors in the estimate), so emphasize you want your car charged above 70% (preferably 80-90%) at delivery.

Caveat 2: Relevant to current time of year: it probably won't work well when the car battery is very cold (not sure how this will work). If you've got blue snowflake or cold battery indications, don't bother calculating. If the vehicle was kept inside the delivery center you'll probably be fine. You might be able to warm the car battery from the app (if the car is plugged in - unlikely) before signing papers if they let you, but it'll be a while. The point is that this calculation can be thrown off by cold conditions.

This method, at the current time, should work on any Model 3 or Model Y vehicle. Probably any Tesla vehicle, but no idea.

As an example, on my 2018 Model 3, my capacity is 71kWh (down from initial value of ~77kWh). This is perfectly normal and expected.


118mi*477Wh/mi / 0.79 = 71250Wh = 71kWh (only 2 significant digits, so saying 71.3kWh is meaningless)

View attachment 620598

 

[jjrandorin]

Please stay tuned for a possible update, in an attempt to make it more clear / easier to understand.

 

[jjrandorin]

Thanks to @AlanSubie4Life and @scottf200 for the additional clarity, and for taking the time to put together the following information to assist members (and lurkers) in easily determining this information.

Thanks again, you two!

======================================================
From @AlanSubie4Life

To add clarity on how to do these calculations, please see the following link, where you can plug in your own numbers and calculate your capacity:

(232 mi) * (259 Wh/mi) / 0.84 in kWh - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

Here is a sample picture of the screen showing how to gather the data; selecting "Average Range" is critical:

Using an Excel spreadsheet, you can redo the calculation at any time, if you wish (this is from a Model X; this method works for all known Tesla vehicles, at this time). The kWh values are only accurate to the nearest kWh (92kWh in this case):

Thanks to @scottf200 for his suggestions.