What does this mean in practice? The flow of electrons must be precisely controlled in order to adapt the power of the electric motor to the driving situation. Even an electric car needs a type of injection system, which is handled, in this case, by the power electronics connected to the electric motor. On top of that, power electronics have another important job. The vehicle battery, a lithium-ion battery, can emit and receive direct current exclusively. Modern electric drives in cars, however, always use alternating current, and its generation is controlled by power electronics. If the vehicle brakes and the electric motor acts as a generator, the alternating current generated must be rectified before it can be stored in the battery. As in everyday use, the power in the power electronics continuously occurs in both directions, the efficiency of the power electronics is decisive for determining how far an electric car can go on one battery charge. Modern power electronics, such as the systems that ZF develops at its Bavarian Auerbach location, already achieve more than a 95% efficiency level in the WLTP cycle.