A battery system is disclosed. In one embodiment, the system includes i) a plurality of battery modules each of which is configured to store power, wherein each battery module is electrically connected to at least one other battery module and ii) a plurality of management units configured to monitor states of the battery modules. Each management unit is electrically connected to at least one other management unit and one or more of the battery modules. Each management unit may include: at least one measuring unit configured to perform the monitoring and a receiving unit configured to i) receive measurement data including the monitoring results from the measuring unit via a first communication protocol and ii) receive measurement data from another receiving unit included in another management unit via a second communication protocol different from the first communication protocol.