DIAGNOSIS DEVICE AND DIAGNOSIS METHOD FOR SECONDARY BATTERY, AND VEHICLE

摘要

A diagnosis device diagnoses the state of degradation caused by metallic lithium deposition in a lithium ion secondary battery (hereinafter referred to as "battery") configured by connecting a plurality of battery blocks in series. When a diagnosis start condition is satisfied, the diagnosis device starts the discharge of the battery and calculates, for each of the battery blocks, a block discharge quantity (Q) discharged from the battery from when the voltage (Vb) of each battery block drops to a measurement start voltage (Vs) until dropping to a measurement end voltage (Ve). The diagnosis device determines that the battery is in "a brand-new state" when every block discharge quantity (Q) is larger than a brand-new state determination threshold (A1), determines that the battery is "usable" when every block discharge quantity (Q) is larger than a nonuse determination threshold (A2), and determines that the battery is "unusable" when at least any one block discharge quantity (Q) is below the nonuse determination threshold (A2).