A quick charging device connects, in a charging operation, a plurality of battery modules in series, and connects the battery modules that are connected in series to a charger, and selects, in a discharging operation, one of the battery modules, and connects the selected battery module to a load unit. When the amount of charge in the battery module connected to the load unit drops by a predetermined amount during the discharging operation, the quick charging device connects another battery module having the largest amount of charge to the load unit.