CHARGED STATE MANAGING APPARATUS FOR SECONDARY BATTERY

PROBLEM TO BE SOLVED: To obtain a charged state managing apparatus for second battery in which the charged state of a second battery being charged/discharged repeatedly at ransom can be detected accurately from the terminal voltage thereof. SOLUTION: The charged state managing apparatus for second battery comprises means for detecting the open voltage of a second battery, a table storing relationship between the open voltage of the second battery and the charged state thereof, and means for storing the maximum charged state of the second battery. A charged state detecting means detects the open voltage after stopping discharge (step S8) and determines the charged state SOCx based on the open voltage with reference to the table (step S9). If the charged state SOCx is lower than a minimum charged state SOCmin stored in the memory means (step S10), the charged state SOCx is outputted as a current charged state SOC (step S12) and the minimum charged state SOCmin is updated by the charged state SOC (step S11).