Abstract: A lithium-ion secondary battery includes an aluminum case, an electrolytic solution, a positive plate, a negative plate, a positive terminal, a negative terminal, and voltage sensors. The positive terminal and the negative terminal project to the outside of the case while being insulated from the case. The voltage sensor is connected between the case and the positive terminal and detects the potential of the positive terminal with respect to a potential VR of the case. The voltage sensor is connected between the case and the negative terminal and detects the potential of the negative terminal with respect to the potential VR of the case. From the detected results, the states of the positive plate and the negative plate are separately detected.

Abstract: A lithium-ion secondary battery includes an aluminum case, an electrolytic solution, a positive plate, a negative plate, a positive terminal, a negative terminal, and voltage sensors. The positive terminal and the negative terminal project to the outside of the case while being insulated from the case. The voltage sensor is connected between the case and the positive terminal and detects the potential of the positive terminal with respect to a potential VR of the case. The voltage sensor is connected between the case and the negative terminal and detects the potential of the negative terminal with respect to the potential VR of the case. From the detected results, the states of the positive plate and the negative plate are separately detected.