The battery management system includes a vehicle and a center. The vehicle includes an acquisition unit that acquires vehicle data, and a transmission unit that transmits the vehicle data to the center. The center includes a reception unit that receives vehicle data from the vehicle, and a determination unit that determines a state of the battery based on the vehicle data. When the vehicle is not parked, the determination unit determines that the battery is in a temporary overdischarge state, when the voltage of the battery when the vehicle is started is less than a first voltage and the integrated value of the charge and discharge amount of the battery is in a first state in which the integrated value of the charge and discharge amount of the battery is less than a first charge and discharge amount.