EV Technology

This is the typical vehicle on the road today powered by an engine fueled by gasoline or diesel. Combustion takes place in cylinders in the presence of air to drive pistons or a rotor that translate mechanical energy through a crankshaft and gearing system to an axle that turns the wheels.

This vehicle has both an internal combustion engine (ICE) and electric motor propelling the vehicle. A typical design recharges the battery using the ICE and the regenerative braking system. Under certain conditions, only the ICE or only the electric motor will directly power the drive train. All of the energy used is provided by gasoline – there is no plug.  Popular makes/models include the Toyota Prius, Honda Insight, and Ford Escape.  General Motors offers a mild hybrid drivetrain called “eAssist”.

This is similar to a hybrid vehicle (HEV) but with a larger battery that can be plugged into a power source such as an electrical outlet to recharge. The PHEV (also known as “Extended Range Electric Vehicle” or EREV) has the advantage of all-electric operation in addition to hybrid operation. Under all-electric operation, the drive train is powered exclusively by the battery. If more power is needed the gasoline ICE starts automatically to assist.   Regenerative braking is still employed to recharge the battery. If the plug-in battery is depleted, the vehicle operates as a conventional HEV.

The Chevy Volt is the first production EREV and the plug-in Prius will be available in the summer of 2012.  The Chevy Volt has a unique drive train with a four-cylinder ICE generator.  The generator is not needed to drive the electric motor until the battery has been discharged after about thirty-five to forty miles.  General Motors dubs the Volt an Extended Range Electric Vehicle since it starts off all-electric and the gas generator kicks in only when needed to extend the range.  Hawaiian Electric Company has had use of several Chevy Volts as part of two demonstration projects.

This vehicle is entirely powered by electricity stored in its battery.  EVs must be plugged in to an external supply to charge the battery.  The energy storage system and electric motor technologies are the keys to its performance and range. The storage medium must either be recharged or exchanged.  Battery storage technology is maturing as well to lighter media with higher energy capacity/volume density.  Current EVs include the Nissan Leaf and the Mitsubishi iMiEV, with many others such as the Ford Focus to be available in 2012.  Typical range with a full charge is about 80 miles, but varies with driving conditions and model.  Hawaiian Electric Company, Inc. currently has a number of Leafs and a couple iMiEVs.