Battery diagnostic apparatus and program

A battery diagnostic apparatus that is applicable to a battery system including an assembled battery that includes a plurality of unit cells connected in series and a detection unit that is provided in at least one unit cell among the plurality of unit cells and detects a parameter for degradation diagnosis, the battery diagnostic apparatus calculating a state-of-health indicating a degree of degradation of each unit cell, the battery diagnostic apparatus comprising:

• a first calculation unit that acquires the parameter detected by the detection unit for at least one unit cell among the plurality of unit cells and calculates the state-of-health based on the parameter;
• a second calculation unit that calculates a change amount of a state-of-charge caused by energization, for the plurality of unit cells;
• and
• a third calculation unit that, when a unit cell of which the state-of-health is calculated by the first calculation unit among the plurality of unit cells is a first unit cell and a unit cell of which the state-of-health is not calculated among the plurality of unit cells is a second unit cell, calculates a value obtained by multiplying a change amount ratio that is a ratio of the change amount of the state-of-charge of the first unit cell to the change amount of the state-of-charge of the second unit cell by the state-of-health of the first unit cell, as the state-of-health of the second unit cell, wherein:
• the first calculation unit acquires the parameter detected by the detection unit for a low-temperature cell that has a relatively low temperature while the assembled battery is in an energized state, among the plurality of unit cells, and calculates the state-of-health of the low-temperature cell based on the parameter;
• and
• the third calculation unit calculates the state-of-health of the second unit cell with the low-temperature cell as the first unit cell.

A battery diagnostic apparatus that is applicable to a battery system including an assembled battery that includes a plurality of unit cells connected in series and a detection unit that is provided in at least one unit cell among the plurality of unit cells and detects a parameter for degradation diagnosis, the battery diagnostic apparatus calculating a state-of-health indicating a degree of degradation of each unit cell, the battery diagnostic apparatus comprising:

• a first calculation unit that acquires the parameter detected by the detection unit for at least one unit cell among the plurality of unit cells and calculates the state-of-health based on the parameter;
• a second calculation unit that calculates a change amount of a state-of-charge caused by energization, for the plurality of unit cells;
• and
• a third calculation unit that, when a unit cell of which the state-of-health is calculated by the first calculation unit among the plurality of unit cells is a first unit cell and a unit cell of which the state-of-health is not calculated among the plurality of unit cells is a second unit cell, calculates a value obtained by multiplying a change amount ratio that is a ratio of the change amount of the state-of-charge of the first unit cell to the change amount of the state-of-charge of the second unit cell by the state-of-health of the first unit cell, as the state-of-health of the second unit cell, wherein:
• the first calculation unit acquires the parameter detected by the detection unit with at least two unit cells among the plurality of unit cells as the first unit cell, and calculates the state-of-health based on the parameter;
• and
• the third calculation unit calculates, for each second unit cell, the state-of-health of the second unit cell using the change amount of the state-of-charge of the first unit cell having a small temperature difference with the second unit cell while the assembled battery is in the energized state, of the at least two first unit cells, and the state-of-health.