ENERGY STORAGE APPARATUS AND CONTROL METHOD OF ENERGY STORAGE DEVICES

An energy storage apparatus includes: a plurality of energy storage devices connected in series; a voltage detection unit that detects voltages of the plurality of energy storage devices; a discharge circuit that discharges the energy storage devices; and a control unit. The energy storage devices include lithium ion cells. The plurality of energy storage devices is chargeable by an external charger for a lead-acid battery, wherein a charge voltage per cell of the external charger for the lead-acid battery is higher than a maximum voltage of the energy storage device, and wherein the control unit discharges only an energy storage device having a highest voltage out of the plurality of energy storage devices when the plurality of energy storage devices is charged by a charger.