A battery monitoring system comprises a battery control unit (BCU) and a plurality of module control units (MCUs) connectable to battery modules. The BCU comprises a low voltage power supply, a BCU controller, and a reference address signal source connected to an address signaling path. The MCUs receive low voltage power from the BCU. Each MCU comprises an address signal input and output with a signal coupler therebetween for connecting the module control unit along the address signaling path, and an MCU controller. The BCU controller determines a number of MCUs on the address signaling path, and each MCU controller determines the associated MCU's position along the address signaling path, based at least in part on a detected signal on the address signaling path and predetermined properties of the reference address signal and address signal coupler. A ground fault detection unit may provide a fault signal to the BCU controller.