Battery Health

Tessie's Battery Health feature helps you track your battery over time.

How it works

Tesla's Battery Management System (BMS) estimates battery range and capacity. Tessie records and averages these fluctuating estimates after each 5+ kWh charge.

How range health is measured

Health = current capacity ÷ original capacity

Example: 300 mi now ÷ 400 mi when new = 75% health and 25% degradation

Tessie uses battery capacity, not the vehicle's displayed range, which changes with software updates, tires and software settings.

How range health compares to Tesla's battery health test

Tessie compares your battery's current range to its original range when new. Tesla does the same, but may further lower the score based on battery age.

How charge cycles are measured

1 cycle = 1 charge from 0–100%

Example: Charging 80–90% 10 times = one cycle

Tessie estimates past cycles from the vehicle's real-world energy usage patterns and will get more accurate over time as Tessie learns your energy usage.

If any calculations look unusually high or low

It's possible that the BMS calibration has drifted and its calculations are inaccurate. Calibrate it to improve accuracy.

How the original capacity is determined

Tessie uses the fleet average for your vehicle configuration. It may change as data comes in from more users. You can manually set the original capacity by pressing the number on the gauge and battery health will automatically recalculate.

Minimizing degradation

See Minimizing Battery Degradation.

What degradation is normal?

Range and capacity start to decrease immediately and tend to stabilize around a 10% loss. The rate of degradation depends on the type of battery in the vehicle.

Why was there a sudden change?

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.

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.