This is the concept created by the Chevrolet Wo Randa, for the pure electric vehicle equipped with a small displacement internal combustion engine, but the internal combustion engine does not have any mechanical structure directly connected to the wheel, only the lithium battery for the motor power supply. The American Society of Automotive Engineers defines it as "two or more energy storage devices that can be powered either individually or simultaneously."
When the battery is sufficient, the engine stops working, the lithium battery for the motor power supply, driving the vehicle. When the lithium battery power consumption to the default threshold, the engine starts power generation, power supply for the drive motor, lithium battery charging.
Pure electric vehicles need to be equipped with more lithium battery unit in order to achieve longer mileage, there must be charging pile or charging wall box to provide charging, if the battery is over-discharge, may shorten the life; compared with pure electric vehicles, The car can carry less lithium battery unit to protect the battery from deep discharge.