TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The battery management system further comprises: many additional sub-controllers associated with the second sub-controller; many sub-controller processing device configured to receive many power unit control signals from the second power unit and, configures many battery cells, in response to the many power unit control signals received from the second sub-controller; and many sub-controller computer-readable storage devices configured to store operational information of the first plurality of battery cells. The first sub-controller further comprises: a first sub-controller processing device configured to receive operational information from the first many of battery cells; a first sub-controller computer-readable storage device configured to store operational information of the first plurality of battery cells; and a power supply configured to receive a power enable signal and provide power to the first sub-controller processing device in response to receiving the power enable signal. In response to the first power unit control signals received from the controller, the first sub-controller processing device operates to transmit the stored operational information to the controller on the upstream link. The first sub-controller computer-readable storage device is further configured to store the second power unit control signals received from the controller and the first sub-controller processing device operates to transmit the second power unit control signals to the second power unit. A first portion of the first many of battery cells are connected into a first battery module and a second portion of the first many of battery cells are connected into a second battery module, where the battery modules are serially connected to the first sub-controller. The first many of battery cells comprise at least one battery cell of a first chemical composition and at least one battery cell of a second chemical composition. The second power unit is electrically isolated from the first power unit. The first control signal comprises: an instruction to the first management control sub-controller associated with the first power unit to perform a balancing of many battery modules associated with the first power unit; a power enable signal to provide power to the first management control sub-controller of the first power unit; or an initialization command and a first address value, where the configuring operation comprises retrieving the first address value from the first control signal and storing the first address value in an address register associated with the first power unit. The second control signal comprises the initialization command and a second address value, where the second address value is an increment of one from the first address value. The downstream communication receiver is a wired electrically isolated receiver or optical receiver and the transmitter is a wired electrically isolated transmitter or optical transmitter. The method (I) further comprises: receiving the second power unit performance measurement on the upstream communication link configured between the first power unit and the second power unit; storing the second power unit performance measurement in the computer-readable medium; receiving a third control signal from the controller on the first downstream communication link at the first management control sub-controller associated with the first power unit of the battery, where the third control signal comprises a request for the second power unit performance measurement; and transmitting the second power unit performance measurement on a first upstream communication link configured between the first power unit and the controller.