Abstract: A modular battery system includes a plurality of battery modules positioned on a different floor of an enclosure. Each of the plurality of battery modules includes a plurality of battery arrays of rechargeable batteries. A controller is configured to select one of the plurality of battery modules for charging or discharging. A power converter is positioned on a different floor of the enclosure from each of the plurality of battery modules. The power converter is configured to convert an alternating current (AC) input to a direct current (DC) input and to switch the DC input to the selected one of the plurality of battery modules for charging.