The voltage detection means which detect the voltage when charge and discharge of the charge and discharge frequency method of detection null charge and discharge

摘要

PROBLEM TO BE SOLVED: To count the number of cycles in response to the degradation of a battery cell when the degradation occurs in the battery cell due to charging and discharging of the battery. SOLUTION: When a detected battery voltage shifts from the battery level 1 to the battery level 0 (Step ST9), the battery level is set to 0 (Step 10), and the number of cycles is counted up by 1/3 (Step 15). When the detected battery voltage shifts from the battery level 2 to the battery level 1 (Step 9), the battery level is set to 1 (Step 12), and the number of cycles is counted up by 1/3 (Step 15).