Patent ID: 8669739

Claim:
An electric charging system in which an electric vehicle is provided with a charging port that is connected to an electric storage device, and an electric charger that has an electric controller generating supply power is connected to the charging port, and the electric charger is used to charge the electric storage device, the electric charging system comprising: a pair of current carrying lines that connects the electric storage device and the power controller via the charging port and supplies charging power to the electric storage device from the power controller; a relay that is disposed on at least either one of the pair of the current carrying lines between the electric storage device and the charging port and is switched between a connection state and a disconnection state; a voltage measure that is connected to the pair of the current carrying lines between the relay and the power controller and measures a voltage between the current carrying lines; a relay diagnosis unit that, under a state where charging of the electric storage device is interrupted, switches the relay to the connection state or the disconnection state and examines a failure state of the relay based on a change in the voltage due to switching of the relay; and a voltage processor that processes the voltage with a first filter when the electric storage device is charged and processes the voltage with a second filter that has a higher responsiveness than the first filter when a failure diagnosis of the relay is performed based on the change in the voltage due to switching of the relay.