A battery monitoring system is for a battery string(s) at a geographical location, where the battery string(s) includes a plurality of series-connected batteries. The system may include wireless battery monitors each associated with a respective battery, a wireless string monitor associated with the battery string(s), and a wireless access point for communicating with the wireless battery monitors and the wireless string monitor at the location. A battery monitoring cloud server may communicate with the at least one access point via a wide area network (WAN) to remotely determine a configuration of the batteries within the battery strings based upon the wireless battery monitors and the wireless string monitor, remotely collect diagnostic measurement data for the batteries from the wireless battery monitors and the wireless string monitors, and remotely process the collected diagnostic measurement data based upon the determined configuration of the batteries to determine fault conditions and generate alerts accordingly.