A plug-in hybrid (PHEV) is a vehicle with a hybrid drive, i.e. two drivetrains. Today, these are mostly an electric motor and a combustion engine. Unlike the conventional hybrid car (HEV), the lithium-ion battery of a PHEV can be charged both via the combustion engine and externally via the power grid. The advantage of the PHEV is the increase in battery capacity and the associated ability to cover longer distances without local emissions. With sufficient capacity, short distances (about 60 to 80 kilometers) can be covered exclusively in electric mode, while the combustion engine is only used as a generator for recharging the batteries. The possibility of operating the combustion engine alone means that longer driving distances are possible even when the battery is empty.