Charging control method for secondary battery and battery charger

Abstract

A method and a charger for auxiliarily charging a secondary battery to a desired SOC with high accuracy. A charger for a secondary battery includes a charge termination condition storing unit which stores a relationship between open circuit voltages OCV of a plurality of secondary batteries and an amount of change of terminal voltage ΔV until a desired state of charge SOC is reached, which is previously created. A target terminal voltage Vmap at the time of the auxiliary charge is calculated by adding the amount of change of terminal voltage ΔV corresponding to the open circuit voltage OCV of a secondary battery to be auxiliarily charged to the open circuit voltage OCV which is measured. A terminal voltage Vb of the secondary battery at the time of auxiliary charge and the target terminal voltage Vmap are compared to each other by a comparison unit, and when the target terminal voltage Vmap is reached, auxiliary charge is terminated.

Dependencies are inferred from the claim text.