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Plug-In Hybrid Electric Vehicle Basics

A plug-in hybrid electric vehicle (PHEV) uses a battery to power an electric motor and uses another fuel, such as gasoline or diesel, to power an internal combustion engine.

Cutaway diagram illustrating components of plug-in hybrid electric vehicle. Components under the hood include (from the front of the vehicle) a thermal cooling system (rectangular flat box) adjacent to an auxiliary battery (small rectangular box), a DC/DC converter (rectangular box with fins), a power electronics controller (larger rectangular box), an onboard charger (flat box), a transmission (not visible), a spark ignited internal combustion engine (large box) adjacent to an electric generator (cylinder with ridges) and electric traction motor (cylinder), a charge port (electric charging nozzle) at the side of the car, and an exhaust system (pipes emanating from the engine area and continuing to rear of vehicle). Components toward the rear of the vehicle include a traction battery pack (large box), a gasoline fuel tank (slightly larger box), and a fuel filler (fueling nozzle).

The battery pack in a PHEV is generally larger than in a standard hybrid electric vehicle. The larger battery pack allows the vehicle to operate predominantly on electricity during short trips. For longer trips, a PHEV can draw liquid fuel from its onboard tank to provide a driving range similar to that of a conventional vehicle. An onboard computer decides when to use which fuel according to which mode allows the vehicle to operate most efficiently.

The battery can be charged by plugging into an electric power source, through regenerative braking, and by the internal combustion engine. In regenerative braking, kinetic energy normally lost during braking is captured and stored in the battery.

Additional Resources

Learn about NREL's transportation and mobility research.

For more information about plug-in hybrid electric vehicles, visit the U.S. Department of Energy’s Alternative Fuels Data Center.

Use the Alternative Fueling Station Locator to find publicly accessible electric vehicle charging stations across the nation.