A battery control system for controlling charging/discharging of a nickel-metal hydride battery having a hysteresis characteristic for a relationship between voltage and a state of charge, the battery control system comprising: a storage medium configured to store information regarding a plurality of state of charge use ranges having different state of charge upper and lower limits; and a control circuit configured to select one of the plurality of state of charge use ranges depending on a condition of use according to a temperature of the nickel-metal hydride battery to control the charging/discharging of the nickel-metal hydride battery in accordance with the selected state of charge use range, wherein: the plurality of state of charge use ranges include a first use range, and a second use range that includes an state of charge of the same level as the state of charge lower limit of the first use range, characterized in that the control circuit is configured: to detect a voltage of the nickel-metal hydride battery and calculate the state of charge therefrom; to determine whether a current state of charge of the nickel-metal hydride battery is equal to a predetermined state of charge that is included in both the first use range and the second use range; when it is determined that the current state of charge is equal to the predetermined state of charge, to obtain information regarding a memory effect of the nickel-metal hydride battery; and to control the discharging of the nickel-metal hydride battery by lowering a lower limit voltage of each of the state of charge use ranges using the obtained information regarding the memory effect. a storage medium configured to store information regarding a plurality of state of charge use ranges having different state of charge upper and lower limits; and a control circuit configured to select one of the plurality of state of charge use ranges depending on a condition of use according to a temperature of the nickel-metal hydride battery to control the charging/discharging of the nickel-metal hydride battery in accordance with the selected state of charge use range, wherein: the plurality of state of charge use ranges include a first use range, and a second use range that includes an state of charge of the same level as the state of charge lower limit of the first use range, characterized in that the control circuit is configured: to detect a voltage of the nickel-metal hydride battery and calculate the state of charge therefrom; to determine whether a current state of charge of the nickel-metal hydride battery is equal to a predetermined state of charge that is included in both the first use range and the second use range; when it is determined that the current state of charge is equal to the predetermined state of charge, to obtain information regarding a memory effect of the nickel-metal hydride battery; and to control the discharging of the nickel-metal hydride battery by lowering a lower limit voltage of each of the state of charge use ranges using the obtained information regarding the memory effect. to detect a voltage of the nickel-metal hydride battery and calculate the state of charge therefrom; to determine whether a current state of charge of the nickel-metal hydride battery is equal to a predetermined state of charge that is included in both the first use range and the second use range; when it is determined that the current state of charge is equal to the predetermined state of charge, to obtain information regarding a memory effect of the nickel-metal hydride battery; and to control the discharging of the nickel-metal hydride battery by lowering a lower limit voltage of each of the state of charge use ranges using the obtained information regarding the memory effect.