Abstract: Provided is an electric energy storage device capable of improving a charging efficiency when electric power supplied with an input current having a current value repeatedly exhibiting peaks and valleys is to be storaged by using a secondary battery and an electric double-layer capacitor. The electric energy storage device includes: an electric double-layer capacitor; and a battery unit including at least one secondary battery, the battery unit being connected in parallel to the electric double-layer capacitor, in which: a ratio of an internal resistance of the electric double-layer capacitor to an internal resistance of the battery unit is determined according to parameters relating to the input current.

Abstract: Provided is an electric energy storage module control device for controlling an electric energy storage module (2) including a plurality of capacitors (20) connected in series, the electric energy storage module control device including a voltage control circuit (10) connected in parallel to each of the plurality of capacitors (20), in which the voltage control circuit (10) includes a constant voltage control part (14) for controlling and preventing a voltage across the constant voltage control part from exceeding a predetermined voltage, and a resistor (12) connected in series to the constant voltage control part (14), and the predetermined voltage is lower than an upper limit applied voltage of each of the plurality of capacitors (20).

Abstract: Provided is an electric energy storage device capable of improving a charging efficiency when electric power supplied with an input current having a current value repeatedly exhibiting peaks and valleys is to be storaged by using a secondary battery and an electric double-layer capacitor. The electric energy storage device includes: an electric double-layer capacitor; and a battery unit including at least one secondary battery, the battery unit being connected in parallel to the electric double-layer capacitor, in which: a ratio of an internal resistance of the electric double-layer capacitor to an internal resistance of the battery unit is determined according to parameters relating to the input current.