DEGRADATION DETERMINATION DEVICE FOR SECONDARY BATTERY

A degradation determination device for a secondary battery is used for a hybrid vehicle, and configured to determine degradation of the secondary battery. The hybrid vehicle includes an engine configured to output power, a motor configured to output power, the secondary battery configured to supply electric power to the motor, and a control device configured to execute travel control in which the engine and the motor are controlled. The degradation determination device includes a controller. The controller is configured to determine degradation of the secondary battery based on data of a third parameter in a predetermined period. The third parameter is the difference between a first parameter based on the accelerator operation amount and a second parameter based on a fuel injection amount.