Patent ID: 8684596

Claim:
A secondary battery temperature-estimating apparatus for estimating a temperature of a secondary battery, comprising: a ripple generating section that is connected to the secondary battery, adapted to cause a ripple alternating current at a predetermined frequency to flow in the secondary battery, and configured to effectively increase the temperature of the secondary battery by setting the predetermined frequency to around 1 kHz; an electric current detecting section that detects an electric current charging or discharging the secondary battery; a discharge amount estimating section that estimates a discharge amount when the ripple current flows in the secondary battery; a state of charge (SOC) estimating section that estimates a state of charge (SOC) of the secondary battery by adding a variation amount of the state of charge estimated based on said estimated discharge amount to a state of charge before the ripple current flowed in the secondary battery; a loss estimating section that estimates an open-circuit voltage (OCV) of the secondary battery based on the state of charge thereof with the use of a SOC-OCV map prepared in advance, and estimates an energy loss of the secondary battery based on said estimated open-circuit voltage and said estimated discharge amount; and a temperature estimating section that estimates an amount of change in the temperature of the secondary battery based on the energy loss of the secondary battery estimated by the loss estimating section and estimates the temperature of the secondary battery by adding the estimated amount of change in the temperature to the temperature before the ripple current flowed in the secondary battery.