DEGRADATION-DETERMINATION SYSTEM AND METHOD FOR DETERMINING DEGRADATION OF SECONDARY BATTERY

A degradation-determination system includes a volume change detecting unit configured to detect a volume change of a lithium-ion battery, a capacity change detecting unit configured to detect a capacity change of the lithium-ion battery, and a charge control unit configured to control charge of the lithium-ion battery. The charge control unit is configured to determine that the lithium-ion battery is in a state of degradation, upon occurrence of a condition in which volume expansion of the lithium-ion battery is detected by the volume change detecting unit, in conjunction with a condition in which a decrease in a capacity of the lithium-ion battery is not detected by the capacity change detecting unit.