METHOD OF DETERMINING CRACK IN POSITIVE ELECTRODE ACTIVE MATERIAL OF RECHARGEABLE BATTERY AND METHOD OF CONTROLLING RECHARGEABLE BATTERY, APPARATUS OF DETERMINING CRACK IN POSITIVE ELECTRODE ACTIVE MATERIAL OF RECHARGEABLE BATTERY AND APPARATUS OF CONTROLLING RECHARGEABLE BATTERY, AND VEHICLE EQUIPPED WITH THESE APPARATUSES

摘要

PROBLEM TO BE SOLVED: To provide a method and apparatus of determining a crack in a positive electrode active material of a rechargeable battery that are capable of suppressing development of a deterioration of the material by detecting an occurrence of a crack in the material in its early stage.SOLUTION: For a rechargeable battery that is a determination target, the determining method of the present invention more than once obtains tuple data that is a tuple of a square root of an integrated value of a discharging amount from a time of a brand-new condition to a current time and a battery capacity at the current time. The method then calculates a first determination coefficient upon an approximation of the plural pieces of the tuple data by a linear function. The method then calculates a second determination coefficient upon approximation of the plural pieces of the tuple data by a quadratic function only when the obtained first determination coefficient is smaller than a predetermined acceptable value that indicates that the battery is permitted to be used without any change. If the second determination coefficient is equal to or larger than a threshold, it is determined that a crack occurs in a positive electrode active material. If the second determination coefficient is smaller than the threshold, it is determined that a deterioration other than a crack occurs in the positive electrode active material.