Charging control apparatus, method of controlling the charging process, and power output apparatus

摘要

To prevent excessively charging a secondary battery, which is subjected to repeated charge and discharge in a specific charged state that is lower than a full charge level, a temperature gradient of the secondary battery due to a charging process is measured, and the charged state of the secondary battery is determined to be close to the full charge level at the time point when the temperature gradient abruptly increases. The charging process is stopped based on the determination. In the case where the secondary battery is repeatedly charged and discharged, the observed temperature gradient is corrected. The correction subtracts a temperature rise due to a discharging process from the observed temperature gradient and thereby determines a temperature gradient relating to only the charging process. The correction utilizes a table that stores a relationship among the temperature rise due to the discharging process, the discharge current of the secondary battery, and the initial temperature of the secondary battery. It is also possible to determine the charged state of the secondary battery based on the temperature gradient only when the observed charge-discharge electric current shows that the secondary battery is being charged.