Tesla’s high-voltage battery becomes less efficient over time, thus reducing your car’s range. That’s why it is very important to monitor your battery’s health and for that reason Tesla has designed a specific test you can do at home on your own vehicle. 

This got us curious to see how much our own S3XY cars have degraded over the years, so we decided to do the test ourselves across multiple models - the 2026 RWD Model Y, the 2024 Model 3 Highland, and the 2019 Model 3 Performance. We think that comparing different generations of cars will show some interesting results.

To see how it went, you can check the video below:

Test Design

The Model Y and the Highland have 60 kWh LFP battery while the 2019 Model 3 has Lithium-ion NCA battery. 

Before beginning the test, there are certain conditions that need to be met:

1. There should be no active alerts related to the battery or thermal system.

2. Ensure your Tesla is in Park Mode.

3. There should be no scheduled updates or updates that are in progress.

4. The car needs to be at 20% SOC or less.

5. It has to be plugged to an AC charger with a minimum of 5 kW of power.

When you are ready to begin,  go to Controls -> Service -> Battery Health Test. A pop-up with instructions will appear on your display. Carefully read through it before proceeding. Then, press Start Test.

You will hear the motors and the climate system start running in order to drain the battery to 0% SOC and then recharge it to 100%. To keep track, a progress bar and an estimated time remaining will appear on the Tesla screen and in the app.

During the test, there are things that you should be aware of:

1. Avoid interacting with your vehicle (for example, by trying to unplug it) or tamper with the Tesla App, because you risk canceling the test by accident. 

2. If you wish to cancel the test, you can do so through the screen or the Tesla App. In this case the car will start recharging to the set charge limit.

3. The test may take up to 24 hours to run.

4. Vehicle features like Sentry Mode and climate controls will be disabled.

5. While the test is running, your car may produce noise and heat which is normal.

6. For certain portions of the test, the Tesla screen will be turned off.

When the test is done, your Tesla screen will display a percentage number that represents the total amount of energy your car has retained from its original capacity when it was new. For example, if you have a score of 83%, this means your Tesla’s battery kept 83% of its original energy storage.

Our Results

Now that we have explained the basis of the test, here are our final results:

- For the Highland, we have 93% of battery health with nearly 40,000 km mileage. This means 7% of degradation in a little over 2 years.

- For the base Model Y we have 100% battery health which is not surprising since this car is still relatively new at this point in time.

- For the 2019 Model 3, we have 83% with nearly 100,000 km on the clock. This score seems too low compared to the average Tesla, but keep in mind that this car in particular underwent rigorous testing for our products and modifications. The result is 17% of battery degradation in 7 years, which is quite impressive, especially considering its age and extensive use. It may seem like a lot, but for comparison, a 3-year-old Volkswagen ID.3 with 100,000 km on the clock has 23% of battery degradation.