Abstract: A battery state estimation device includes: a first state of charge (SOC) calculator that calculates a first SOC using a first method that uses the battery model parameter of a battery; a second SOC calculator that calculates a second SOC using a second method different from the first method; an alternating-current (AC) impedance measurement unit that measures the AC impedance of the battery when the error between the first SOC and the second SOC is greater than a predetermined threshold; and a battery model parameter calculator that calculates a battery model parameter using the measured AC impedance. The first SOC calculator recalculates the first SOC using the battery model parameter calculated.

Abstract: A current detector includes: a printed circuit board; and a resistor for detecting an electric current of the electrochemical device, wherein a connector having a first terminal is mounted on the printed circuit board, and the resistor has a second terminal which is brought into contact with the first terminal.

Abstract: A management device for an energy storage device, the energy storage device being mounted in a vehicle and configured to supply power to a specific load that consumes power during parking. The management device includes: a circuit board equipped with a processing unit; a resistor that detects a current of the energy storage device; and a connecting member that electrically connects the resistor and the circuit board. The processing unit calculates SOC of the energy storage device based on the current detected by the resistor. The connecting member includes a signal line, and a shield layer that shields the signal line. One end of the signal line, is connected to the resistor by welding and joining, and the other end of the signal line, is connected to the circuit board by welding and joining.

Abstract: A current detector includes: a printed circuit board; and a resistor for detecting an electric current of the electrochemical device, wherein a connector having a first terminal is mounted on the printed circuit board, and the resistor has a second terminal which is brought into contact with the first terminal.