Diagnostic device for degradation of rechargeable Li-ion battery

摘要

A diagnostic device which can measure quickly and has simple circuit is provided. A charge/discharge circuit 2 supplies charge current to a rechargeable battery 10 and discharges the rechargeable battery 10. The charge/discharge circuit 2 also breaks charge current or discharge current of the rechargeable battery 10 in charging or discharging. A voltage measurement part 6 measures terminal voltage of the rechargeable battery 10 after breaking the charge or discharge current. Diagnostic means 8 judges whether the rechargeable battery 10 is deteriorated or not based on the measured voltages. Voltage change of deteriorated rechargeable battery 10 after breaking the charge or discharge current is more rapid than that of healthy rechargeable battery 10. The diagnostic means 8 can judge whether the rechargeable battery 10 is deteriorated or not based on such voltage change.