Abstract: A power supply apparatus for a vehicle. An electronic controller outputs information for controlling braking of a vehicle. A battery supplies electric power to a brake via the electronic controller. A power supply backup unit as an auxiliary power supply includes a capacitor unit formed of a plurality of capacitors and a detection unit for detecting an abnormality in the capacitor unit, and supplies electric power to the brake when the battery is in an abnormal state. In charging or discharging the capacitor unit, the detection unit measures an internal resistance value of the capacitor unit, and measures an internal capacitance value from the rate of change of voltage per unit time. The detection unit judges whether or not the capacitor unit is in a normal state based on the internal resistance value and the internal capacitance value.

Abstract: A power supply apparatus for a vehicle. An electronic controller outputs information for controlling braking of a vehicle. A battery supplies electric power to a brake via the electronic controller. A power supply backup unit as an auxiliary power supply includes a capacitor unit formed of a plurality of capacitors and a detection unit for detecting an abnormality in the capacitor unit, and supplies electric power to the brake when the battery is in an abnormal state. In charging or discharging the capacitor unit, the detection unit measures an internal resistance value of the capacitor unit, and measures an internal capacitance value from the rate of change of voltage per unit time. The detection unit judges whether or not the capacitor unit is in a normal state based on the internal resistance value and the internal capacitance value.