COOLING SYSTEM FOR SECONDARY BATTERY

A secondary battery (10) is installed on an electric vehicle (90) and includes a cooling fan (40), a temperature sensor (61) and a controller (70). The controller (70) is configured to drive the cooling fan (40) at a fixed command value for a predetermined period, when the temperature of the secondary battery (10) becomes equal to or higher than a first predetermined temperature after the electric vehicle (90) is started. The controller (70) is configured to detect a presence or absence of an abnormality in the cooling fan (40) based on an actual rotational speed of the cooling fan (40) during the predetermined period. The controller (70) is configured to inhibit driving of the cooling fan (40) at the fixed command value when the temperature of the secondary battery (10) is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature.