Power storage device having life determination function, and battery life determination method

摘要

PROBLEM TO BE SOLVED: To provide a battery pack of lithium ion secondary battery capable of determining the life accurately even under a variety of temperature environment, and to provide a power storage device.SOLUTION: Life of a battery pack can be determined accurately regardless of the external environmental temperature by using a battery pack consisting of the series connection of a first electric cell having an inflection region in the charge and discharge curve indicating charge and discharge characteristics, and a second electric cell having an inflection region in the charge and discharge curve, the capacitance in high voltage region is larger than that of the first electric cell, and the cycle deterioration is faster, where each electric cell has a wiring for measuring the voltage, a voltage measurement device for measuring the voltages of the first and second electric cell, and a comparator for determining the life of the battery pack from the voltage value of the voltage measurement device.