Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for smart electric vehicle charging and a mediator device for the same. In one aspect, a method includes receiving a signal, at a first connector, indicative of a charging capacity of a charging station, from the charging station, and providing a signal indicative of a second charging capacity at a second connector to an electrical vehicle, wherein the second charging capacity is determined based on optimization data received from an optimization service