California Air Resources Board

Familiarize Yourself with the Acronyms and Terminology Surrounding Zero-Emission Technology

Zero-Emissions Vehicles (ZEV): Vehicles that produce zero tailpipe exhaust emissions of any criteria pollutant or greenhouse gas under all possible operational modes or conditions.

Battery Electric Vehicles (BEV): Vehicles that run entirely on electricity and can be recharged from an outside energy source like the electricity grid. They use an electric motor instead of an engine and a battery pack instead of a fuel tank.

Hydrogen Fuel Cell Electric Vehicles (FCEV): Vehicles that use a hydrogen powered fuel cell instead of an engine to generate electricity for the batteries and electric motor. These vehicles generally utilize the same components as a battery electric vehicle, but with the addition of a hydrogen fuel cell and hydrogen storage tank.

Near-Zero Emission Vehicles (NZEV): Vehicles that combine a conventional gasoline, diesel or natural gas-powered engine with a battery that can be recharged from the electrical grid. The vehicle is capable of operating like a ZEV for a minimum number of miles. Also referred to as a “Plug-in Hybrid” vehicle with the acronym: PHEV.

Range: For battery electric vehicles the range is the distance a vehicle will travel, or is projected to travel, on electric power before its battery charge is exhausted. Range is an estimate that can vary based on battery size and can be reduced by payload, the grade of a hill, cold and hot weather, aggressive driving, speeds -whether too high or low and, the use of accessories like lights and especially cabin climate controls. For fuel cell electric vehicles, the range is the distance a vehicle is projected to travel before there is no longer fuel available in the tank of the vehicle.

Regenerative Braking: The conversion of a vehicle’s kinetic energy into chemical energy which is stored in the battery-powered electric vehicle battery and can be used as electricity to power the electric motor.

Battery Pack: The complete power-storage component in a ZEV, including individual battery cells packaged into modules, they are also equivalent to a fuel tank on a conventional truck.

Electric Drive Train: The group of components that deliver power to the drive wheels to drive the vehicles forward. This is equivalent to the powertrain/transmission on a conventional truck.

Battery Management System: A system of supporting electronics and cooling components that control charging rates and battery temperature, which is similar to the radiator on a conventional truck.

Battery Capacity: The energy contained in an electric vehicle's battery pack. The vehicle’s range depends on the size of its battery, and how efficiently the vehicle uses that energy. The capacity is measured in kilowatt-hours, which is the ability of a battery to deliver a set power output (in kilowatts) over a period of time (in hours).

Voltage (Volts): The measure of electrical potential. Like pressure, it measures how strongly electricity is being "pushed" through a circuit. Voltage is measured in Volts. Volts = watts / amps.

Amperes (Amps): The measure of the flow of electricity. Like volume, it measures how much electrical charge is moving past a given point in one second. This term is used when describing the amount of electric current that a circuit can provide. Amps = watts / volts.

Kilowatt (kW): The measure of electrical energy that is equal to 1,000 watts. This unit of measure is commonly used throughout the ZEV charging and operations space. A 50 kW charger is five times more powerful than a 10 kW charger. Using a water pipe analogy, it refers to how much water (or energy) is flowing through a pipe at any point in time. Kilowatts can also be converted to horsepower as a measure of power, where 1 kW equals 1.34 horsepower.

Kilowatt-Hour (kWh): The measure of how much electrical energy flows (generally used or dispensed) over one hour. Using a water pipe analogy, you can think of kWh as the equivalent to how much water comes out of the pipe and into a bucket in one hour. The size of a ZEV battery is measured in kWh, which describes the total energy capacity. If the useable battery capacity is 100 kWh, and the vehicle gets two miles per kWh, then the range would be 200 miles per charge. kWh = (KW × hrs).

Level 1 Charger: Charging equipment that uses 110/120 volts, which is typical of most standard North American household outlets. Level 1 charging power output varies slightly but is typically between 12 amps and 16 amps of continuous power. At these levels of output, a Level 1 charger is estimated to deliver an average power output of about 1.3 kW to 2.0 kW. Level 1 chargers are less commonly used in the commercial space.

Level 2 Charger: Charging equipment that uses 208/240 volts, which is typical of most outlets used to power a clothes dryer or an oven. Level 2 chargers are available with a variety of power outputs from 16-40 amps which can deliver between anywhere from about 3 kW to 20 kW of power. Most light-duty (Class 2b-3) battery electric vehicles are a good fit for Level 2 charging, but most medium-duty (Class 4-6) vehicles can also utilize this level charger if they have significant down time available to charge, such as overnight.

Direct Current (DC) Fast Charger: The highest-powered chargers on the market can provide up to 350 kW of capacity today and potentially several thousand kW in the future. A DC fast charger can typically provide a full charge to a BEV with a 100-mile range battery in about 30 minutes. Vehicles with larger batteries or vehicles with less time to charge are more likely to need DC Fast Charging.

Depot Charging: A charging strategy that involves charging a BEV at the fleet’s parking area commonly using Level 2 chargers and DC fast chargers.

Opportunity charging: A charging strategy that involves adding a partial charge to a BEV during daily operations when moments of downtime are present such as loading or unloading. The specific strategy varies with a vehicle’s route and often includes using DC fast chargers.

Fuel Cell: The fuel cell generates electrical power and is equivalent to an engine on a conventional vehicle.

Hydrogen Tank: Typically made of overwrapped composites, such as carbon fiber, to store hydrogen; equivalent to a fuel tank on a conventional vehicle.

Learn more about zero-emission vehicle terms using the following resources:

Drive Clean Glossary of Terms
Green Cars Electric Car Terminology
Cars.com - Electric Vehicles: Understanding the Terminology