Tesla battery capacity

Last updated 26-Nov-2023

How to use calculate battery capacity

Many people want to know about the level of degradation of their battery. There are two ways to calculate this without plugging in specialist computer equipment, one uses some basic information fromt he energy screen, and the second is via the API. This method does the latter, you provide a token that enables us to talk to the car, we will collect the required data, calculate the usable battery capacity, and compare you cars to similar cars.

This is best done when the car battery is warm. A cold battery will have reduced capacity compared to when the battery is warm. We also require the last charge to have added 20 miles or more, the larger the amount the better, as the car efficiency is calculated using data from the last charge. We could calculate it using smaller data but we know the inaccuracy would be too large to be meaningful.

As this approach needs to contact the car, it can time out. If this happens, please refresh the results.


Please copy your Refresh token into the box below


We have created a utility to generate a Tesla token. This utility uses a Tesla feature so we do not need your Tesla user name and password, and will return the Tesla token (which expires very quickly) and the vehicle ID for each car on your account. We also supply the refresh token for those that want to use the tokens on a 3rd party application but wish to use an independant website to generate the token.

The video covers the different methods of calculating the userable capacity and we recommend watching this to see how simple the approach is.

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