Battery Health

Battery capacity decreases with usage. Our Battery Health tracking helps you visualize and track it.

How does it work?

The Battery Management System (BMS) in your Tesla is continuously estimating how much energy is in the battery. Tessie collects capacity and range BMS estimates every time you charge 5 kWh or more so you can track the state of your battery.

Since these measurements fluctuate, it's important to focus on the average and not a single data point.

How accurate is it?

Internal and external tests typically show around 99% accuracy when compared to the Service Mode Battery Health test.

Tessie usually shows degradation within about 1.0-1.2% of the Service Mode test, with a tendency to show slightly less than actual degradation because Tessie uses a running average, including recent measurements when the battery was less degraded.

Accuracy ultimately depends on the data the vehicle sends, which depends on how well calibrated the vehicle's Battery Management System (BMS) is. The more often you charge from low battery to full battery, the more calibrated the BMS will be. Learn more about calibrating the BMS.

How are capacity and max range measured?

Capacity and Max Range represent the average of the last 30 measurements sent by your vehicle.

If you have Direct Telemetry enabled, you can see these measurements in real-time under Battery > Energy and Range.

How is degradation measured?

Degradation is the current capacity divided by the original capacity when the vehicle was brand new.

Here's an example of how you can track degradation yourself:

If you charge your vehicle from 0-100% when it's brand new, and the vehicle reports that 100 kWh was added to the battery, your original capacity is 100 kWh.

If you charge from 0-100% again after 100,000 miles, and the vehicle reports that 90 kWh was added to the battery, your current capacity is 90 kWh.

90 kWh current capacity / 100 kWh original capacity = 90% battery health (10% degradation)

Tessie does this calculation for you, continuously. If you didn't use Tessie when your battery was brand new, don't worry — we'll use our fleet average new battery capacity for your vehicle configuration.

If degradation or capacity looks unusually high or low

It's possible that the BMS calibration has drifted and its calculations are inaccurate. You can help it learn how much energy is in the battery by calibrating it.

Determining the original capacity

If you didn't use Tessie when your battery was brand new, we'll use our fleet average new battery capacity for your vehicle configuration. The number may change as Tessie gains more users with the same battery and gets more data about what the average capacity is when the vehicle is factory fresh.

If your battery capacity is reading far above or below the fleet, it's indicative that your battery has a different capacity. You can find the correct value by changing the capacity until your measurements line up with the fleet average.

You can change the original capacity by pressing the number on the gauge and battery health will automatically recalculate.

How can I minimize degradation?

Check out Minimizing Battery Degradation.

What amount of degradation is normal?

Capacity starts to decrease immediately, and tends to stabilize around a 10% loss. Some batteries degrade slowly and level off around 100,000 mi or 150,000 km, but others may degrade and level off much more quickly.

Why was there a sudden change in capacity or range?

This can happen if a vehicle has a configuration change that affects range, like changing wheel sizes, or when Tesla updates range via over-the-air updates.

When this happens, it's a good idea to calibrate the Battery Management System to help it relearn how much energy is in the battery.

How are charge cycles measured?

Charge cycles represent the number of times the battery has charged the equivalent of 0% to 100%. For example, charging from 80% to 90% ten times is one charge cycle.

For the time prior to Tessie tracking your charging data, Tessie estimates charge cycles using the vehicle's real-world energy usage patterns. This estimate will become more accurate over time as Tessie learns your energy usage.

What happens if the battery gets replaced?

Use the Set Battery Date button and select the date the new battery was installed. Battery health will recalculate using data from the new battery.