Patent ID: 8604755

Claim:
A lithium-ion secondary battery system comprising: a lithium-ion secondary battery having a cathode, an anode including carbon, and a non-aqueous electrolyte [doesn't teach this]; a charge/discharge circuit for putting the lithium-ion secondary battery on charge according to a charge control parameter; and an arithmetic processing section for controlling the charge/discharge circuit, wherein the arithmetic processing section obtains battery characteristics of the lithium-ion secondary battery, changes a value of the charge control parameter when the arithmetic processing section determines that the battery characteristics satisfies a condition for changing the charge control parameter, and restores the value of the charge control parameter to the value before the change when the charge for the lithium-ion secondary battery is finished, wherein the arithmetic processing section obtains an integrated value of a discharge capacity and a ratio of an amount of voltage change and the discharge capacity as the battery characteristics, changes the value of the charge control parameter when the arithmetic processing section determines that the ratio and the integrated value satisfy respective conditions for changing the charge control parameter, and restores the value of the charge control parameter to the value before the change when the charge for the lithium-ion secondary battery is finished.