How do I monitor batteries at an unmanned remote site?

Options in increasing order of capability: charger or rectifier alarm contacts into an existing RTU; a monitoring unit reporting over the site’s existing SCADA link via Modbus or DNP3; a cellular-connected monitor where no SCADA link exists; or a full energy management system where the site has generation and storage as well as batteries. The choice is usually determined by what communications the site already has, not by what the monitoring can do.