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:

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

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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: Do not perform the calculation with a very cold battery (near or below freezing); the results may not be correct.

Caveat 3: This method provides a result which INCLUDES the energy buffer below 0% SoC. On Model 3 & Model Y at least, this buffer size is 4.5% of the full pack capacity calculated; e.g., if you calculate 71kWh, your buffer is 3.2kWh (4.5%), and your usable above 0% displayed is 67.8kWh (95.5%).

Caveat 4: Important for new vehicles: This method will not produce a capacity result in excess of a certain threshold; it will be capped at that value. The value depends on the specific model. For example, for 2023 Model 3 Performance, it will not provide a value above ~80.6kWh, even if the new vehicle capacity currently exceeds that. Capacity will drop below that threshold after some time.

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!

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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.