In Huawei SmartLi 3.0, the BCU acts as the cabinet-level “brain” of the lithium battery system, coordinating measurement, control, protection, and communication. Itmanages and supervises BMUsinside the cabinet by collecting key operating data such as voltage, temperature, SOC, and SOH, and by aggregating module information for higher-level management. The BCU supportscharge/discharge managementby monitoring string current and controlling operating behaviors to keep the battery within safe electrical and thermal limits. To ensure consistent performance across parallel strings and cabinets, it implementsintelligent voltage sharing and active current balancing, which helps equalize currents, improve utilization, and reduce uneven aging. For safety and reliability, the BCU providesfault diagnosis and protection, including handling events such as overvoltage, undervoltage, overcurrent, and overtemperature, and it can isolate abnormal loops when required. SmartLi 3.0 also incorporatesinternal short-circuit risk predictionas part of its safety strategy. Finally,group capacity testingis supported as a maintenance function to verify usable capacity and system health.