What functions does a Battery Management System (BMS) perform?

A BMS monitors and protects battery systems: cell voltage monitoring (detect over/undervoltage), current monitoring (prevent overcurrent), temperature monitoring (thermal management activation), state of charge estimation (coulomb counting, voltage-based, model-based), state of health assessment (capacity fade, impedance increase), cell balancing (passive - resistive dissipation, or active - charge redistribution), fault detection and protection (disconnect on unsafe conditions), communication (provide data to system controller), and thermal management control. BMS is critical for lithium-ion safety, performance, and longevity.