BATTERY PACK AND INFORMATION PROCESSING UNIT

PROBLEM TO BE SOLVED: To improve accuracy of estimation of deterioration degree of a secondary battery.SOLUTION: A microcomputer 105 obtains time of day or time, and length of time using a timer 101, and it measures the temperature of a battery pack 100 as well using a temperature sensor 102. The microcomputer 105 also checks an electrical charge of a battery cell 104 and the like, and determines whether or not the battery cell 104 is fully charged. As a result of the determination, if the battery cell 104 is determined as fully charged, the temperature is measured, a temperature coefficient is determined based on the measured temperature, and points are calculated by multiplying the temperature coefficient by a length of time during which the battery cell 104 is determined as fully charged. Points are integrated in a storage 103. The integrated value is referred to by deterioration determination means 220 on a side of the unit body 200, and utilized for estimation of deterioration degree and deterioration state, and charging control for the battery cell 104.