A method of determining state information of batteries , the method comprising: classifying the batteries into at least one battery and remaining batteries; determining state information of the at least one battery during a first switching period among switching periods based on sensing data of the at least one battery during the first switching period and a first battery model; determining state information of the at least one battery during a second switching period among the switching periods, based on sensing data of the at least one battery during the second switching period and the first battery model; classifying the remaining batteries into a first target battery and a first non-target battery in the first switching period; determining state information of the first target battery during the first switching period based on sensing data of the first target battery during the first switching period and a second battery model; determining state information of the first non-target battery in the first switching period based on a first state change amount of the first non-target battery during the first switching period; classifying the remaining batteries into a second target battery and a second non-target battery in the second switching period, wherein the first target battery is the second non-target battery of the second switching period and the first non-target battery is the second target battery of the second switching period, and wherein a battery of which state information is determined using the second battery model is switched from the first target battery to the second target battery; determining state information of the second target battery based on sensing data of the second target battery during the second switching period and the second battery model; and determining state information of the second non-target battery based on a second state change amount of the second non-target battery in the second switching period. classifying the batteries into at least one battery and remaining batteries; determining state information of the at least one battery during a first switching period among switching periods based on sensing data of the at least one battery during the first switching period and a first battery model; determining state information of the at least one battery during a second switching period among the switching periods, based on sensing data of the at least one battery during the second switching period and the first battery model; classifying the remaining batteries into a first target battery and a first non-target battery in the first switching period; determining state information of the first target battery during the first switching period based on sensing data of the first target battery during the first switching period and a second battery model; determining state information of the first non-target battery in the first switching period based on a first state change amount of the first non-target battery during the first switching period; classifying the remaining batteries into a second target battery and a second non-target battery in the second switching period, wherein the first target battery is the second non-target battery of the second switching period and the first non-target battery is the second target battery of the second switching period, and wherein a battery of which state information is determined using the second battery model is switched from the first target battery to the second target battery; determining state information of the second target battery based on sensing data of the second target battery during the second switching period and the second battery model; and determining state information of the second non-target battery based on a second state change amount of the second non-target battery in the second switching period. <EOS>