A range extender is a fuel-based auxiliary power unit (APU) that extends the range of a battery electric vehicle by driving an electric generator that charges the vehicle's battery. This arrangement is known as a series hybrid drivetrain. The most commonly used range extenders are internal combustion engines, but fuel-cells or other engine types can be used.
A prototype AC Propulsion tzero electric car with an external range-extender or genset trailer, 1999
The Chevrolet Volt is a series plug-in hybrid referred by General Motors as "an electric car with extended range."
An optional range-extender is available for the BMW i3, which allows the car to qualify as a range-extended battery-electric vehicle (BEVx) according to the California Air Resources Board regulations.
The discontinued Fisker Karma is an extended-range electric vehicle.
Hybrid vehicle drivetrain
Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power.
The Chevrolet Volt operates primarily as a series hybrid.
Power-splitter series-hybrid Toyota Prius
Early Hybrid Synergy Drive. Generation 1/Generation 2 (chained) ICE-MG1-MG2 Power Split Device HSD is shown. MG2 ratio permanently set at 1:1.
Late Hybrid Synergy Drive. Generation 3 (chainless) ICE-MG1 Power Split Device/MG2 Motor Speed Reduction Device HSD is shown. MG2 ratio permanently set at 2.5:1.