Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Sanyo Electric Co., Ltd.

Shin-Ichi Yuasa

Masato Fujikawa

Jun Asakura

Kenichi Honoki

Even after the battery reaches the last stage of the end of life, the use can be continued. A charging system includes battery pack and charger. During the charge of lithium-ion secondary battery, charge control unit calculates the full charge capacity maintaining rate, sets a first charge current value on the basis of the full charge capacity maintaining rate, and charges the battery. When lithium-ion secondary battery reaches the last stage of the end of life, charge control unit sets a second charge current value lower than the first charge current value set based on the full charge capacity maintaining rate, and charges the battery.

Secondary battery charging system and method, and battery pack

During charging of a secondary battery, a rate of voltage change dV/dt is obtained when a voltage V of the secondary battery reaches a predetermined voltage V, a charge current I for charging the secondary battery is detected, and a rate of change dQ/dt in a quantity of charged electricity Q of the secondary battery is calculated on the basis of the result of the detection. Here, the predetermined voltage Vis a voltage higher than a discharge cutoff voltage and lower than a charge cutoff voltage. Thereafter, a ratio X: dQ/dV, of the rate of change dQ/dt in the quantity of charged electricity to the rate of voltage change dV/dt is calculated. The calculated ratio X is compared with a reference value X, and degradation of the secondary battery is determined on the basis of the result of the comparison.

Method and device for diagnosing secondary battery degradation

It is intended to provide a battery module having a long life by designing such that deterioration proceeds evenly among battery cells. Disclosed is a battery module including a plurality of battery groups being connected in series and each comprising a plurality of battery cells connected in parallel, wherein: a positive electrode terminal and a negative electrode terminal are provided; the battery groups are connected to each other by a plurality of electrically conductive strips; and an electrical resistance value of the conductive strip arranged at a position near a virtual line drawn between the positive electrode terminal and the negative electrode terminal is high, and an electrical resistance value of the conductive strip arranged at a position other than the position near the virtual line is low, the electrical resistance value being measured in a direction of charge and discharge current flow.

Growing community of inventors

Kyoto, Japan

Shin-Ichi Yuasa