Electric power storage system for a vehicle and method for controlling electric power storage system for a vehicle

An electric power storage system for a vehicle, the vehicle including an ignition switch, the electric power storage system comprising:

• an electric power storage device that is mounted on the vehicle;
• a temperature sensor configured to detect and output a temperature of the electric power storage device;
• and
• a controller configured to
• acquire and accumulate the temperature of the electric power storage device with the temperature sensor when the ignition switch is turned ON during a predetermined period,
• calculate an average value of the temperatures of the electric power storage device accumulated during the predetermined period, and
• set the average value as a rest temperature, the rest temperature being the temperature of the electric power storage device available when the ignition switch is OFF,
• wherein the controller is configured to acquire and accumulate the temperature of the electric power storage device at a time when the ignition switch is turned ON by using the temperature sensor every time the ignition switch is turned ON, and
• wherein the controller is configured to estimate the rest temperature by using an average value of a first temperature and a second temperature, the first temperature is a temperature regarded as a maximum value of the plurality of the temperatures and the second temperature is a temperature regarded as a minimum value of the plurality of the temperatures,
• wherein the controller is configured to estimate the rest temperature such that the rest temperature reflects a change in an environmental temperature during a rest of the vehicle.

A method for controlling an electric power storage system for a vehicle, the vehicle including an ignition switch, the electric power storage system including an electric power storage device, a temperature sensor, and a controller, the electric power storage device being mounted on the vehicle, and the temperature sensor being configured to detect and output a temperature of the electric power storage device, the method comprising:

• acquiring, using the temperature sensor, the temperature of the electric power storage device when the ignition switch is turned ON during a predetermined period;
• accumulating, by the controller, the temperature of the electric power storage device when the ignition switch is turned ON;
• calculating, by the controller, an average value of the temperature of the electric power storage device accumulated during the predetermined period;
• and
• setting, by the controller, the average value as a rest temperature, the rest temperature being the temperature of the electric power storage device available when the ignition switch is OFF,
• wherein the temperature of the electric power storage device is acquired, using the temperature sensor, every time the ignition switch is turned ON during the predetermined period, and
• the temperature of the electric power storage device is accumulated, by the controller, every time the ignition switch is turned ON, and
• wherein the controller is configured to estimated the rest temperature by using an average value of a first temperature and a second temperature, the first temperature is a temperature regarded as a maximum value of the plurality of the temperatures and the second temperature is a temperature regarded as a minimum value of the plurality of the temperatures,
• wherein the controller is configured to estimate the rest temperature such that the rest temperature reflects a change in an environmental temperature during a rest of the vehicle.