Glossary of EV Terms

Quick, plain-language definitions for the terms you'll run into while researching EVs.

Quick Answer

The EV terms that matter most: kWh measures battery energy (the size of the tank), kW measures power (how fast energy moves), state of charge is the current battery level, state of health is remaining capacity, EVSE is the charging equipment, and regen braking recovers energy while slowing.

Part of the AutoNetwork Electric Vehicle Guide.

• EV cost of ownership
• EV charging at home and in public
• How to buy an electric vehicle

Frequently Asked Questions

What does kWh mean on an EV?

A kilowatt-hour (kWh) is a unit of energy. Battery capacity is measured in kWh — it is effectively the size of the fuel tank. Efficiency is often expressed as kWh per 100 miles.

What is the difference between kW and kWh?

kW measures power — the rate energy flows, such as a 150 kW fast charger. kWh measures the amount of energy stored or used. Power is the speed; energy is the quantity.

What is regenerative braking?

When you lift off the accelerator or brake, the electric motor runs as a generator, slowing the car and returning energy to the battery instead of wasting it as heat in the brake pads.