Patent ID: 8643341

Claim:
A battery system comprising: a lithium on secondary battery; and a temperature control device for controlling the temperature of the lithium on secondary battery, wherein the temperature control device performs control to maintain the temperature T of the lithium ion secondary battery within the range: 55° C.<T<65° C. for a predetermined length of time, wherein the lithium ion secondary battery is adapted to be mounted as an automobile drive power supply in an automobile, the battery system is configured to enable charging of the lithium ion secondary battery by use of electric power supplied from an external power supply during parking of the automobile, and the temperature control device performs control to maintain the temperature T of the lithium ion secondary battery within the range: 55° C.<T<65° by cooling or heating the lithium ion secondary battery throughout an entire period of time in which the lithium ion secondary battery is charged with electric power supplied from the external power supply from a start of charging the lithium ion secondary battery with electric power to an end of the charging of the lithium ion secondary battery with electric power.