About Charging Efficiency

Tessie measures the energy added to the battery, used by the charger and the overall charging efficiency.

How energy added is calculated

Your vehicle tracks the energy added to the battery pack during charging. Tessie uses this number directly. It's the same as the  +x kW value that can be seen in the vehicle while it charges.

How energy used is calculated

Your Tesla measures the current and voltage from the charger before any efficiency loss occurs.

Tessie monitors these values over time and calculates the power used during the charge.

How charging efficiency is calculated

Charging efficiency is the energy added to the battery divided by the energy used by the charger.

Efficiency is affected by several factors, including the power source, battery temperature, and ambient temperature.

Charging efficiency by charger type

Chargers are typically broken up into three levels, with each level having different efficiency:

• Level 1 (e.g. 120-volt outlets): ~70% charging efficiency
• Level 2 (e.g. 240-volt outlets): ~90% charging efficiency
• Level 3 (e.g. Superchargers, DC fast chargers): ~100% charging efficiency