In one aspect, a power system comprises a power bus, a plurality of energy-storage modules, and a controller. Each energy-storage module is coupled to the power bus and comprises an energy-storage device configured to store energy, an electrical circuit safety device configured to detect safe power conditions in the energy-storage module and break an electrical circuit within the energy-storage module based on a detection of unsafe power conditions in the energy-storage module, and a switch configured to selectively couple the energy-storage device to the power bus. The controller is configured to monitor a state of each of the plurality of energy-storage modules and control a state of the power system based on the state of each of the plurality of energy-storage modules.