8 c charging when sensing that the total voltage of the battery pack 200 has reached the threshold voltage v h for detecting overcharge through a communication with the bms 210 the controller 122 controls the charge discharge unit 120 to stop the charging the controller 122 then records the time t h1 at that point and performs 4 c charging in the 4 c charging when sensing that the total voltage of the battery pack 200 has reached the threshold voltage v h for detecting overcharge the controller 122 stops the charging the controller 122 then performs 2 c charging and 1 c charging in the same manner as above and records the time t h4 when the 1 c charging is finished after that the controller 122 notifies the bms 210 in the battery pack 200 of the obtained time information t h4 t h1 the bms 210 encrypts the temperatures for the charging and the time information t h4 t h1 and then records the encrypted information into the nonvolatile memory 213 as the battery deteriorates and the internal resistance of the battery becomes higher the above described time t h4 t h1 is considered to also become longer accordingly the above described time can replace the deterioration tendency indicator of a battery capacity when a large amount of current flows by the evaluation method utilizing the diagnosis device 100 described in the first embodiment of the present disclosure the present value of a battery to be used in the future can be determined with high precision by the determination method utilizing the diagnosis device 100 typically embodied by the second embodiment a value calculation can be performed in accordance with the purpose of future use by the diagnosis method described in the.