BMS

BMS stands for Battery Management System, a set of hardware and software that monitors and controls rechargeable battery packs to ensure safety, reliability, and optimal performance. BMS is essential in systems where large numbers of cells are connected in series or parallel, as it protects cells from abuse, tracks energy state, and coordinates charging and discharging.

Its primary functions include monitoring cell voltage, current, temperature, and state of charge; estimating state of health and remaining capacity; balancing cell voltages to prevent voltage drift; controlling charging and discharging through protection circuits; and managing thermal conditions, cooling or heating as needed. It also provides data for system controllers and can regulate current limits and fault responses in real time.

Typical architecture ranges from centralized BMS (one controller for the pack) to distributed or modular designs with multiple controllers closer to cell groups. Core components are sensors (voltage, current, temperature), a microcontroller or processor, battery pack interface, cell balancing circuits (passive or active), and a communications backbone (CAN, LIN, I2C, or Modbus).

Applications include electric vehicles, stationary energy storage systems, and portable electronics. In EVs and grid storage, the BMS is a safety-critical element that enforces cell protection, ensures safe charging, and enables accurate state estimation that informs battery thermal management and power electronics.

Standards and safety considerations encompass electrical protection, fault tolerance, and cybersecurity. Relevant standards include UL 1973 for battery packs and modules, IEC 62619 for industrial rechargeable battery packs, and automotive contexts often rely on ISO 26262 for functional safety. Design challenges include aging effects, sensor accuracy, balancing efficiency, and ensuring reliable communication in harsh environments.

Beyond batteries, BMS is also an acronym used for Building Management System, a control system for building services such as heating, ventilation, air conditioning, lighting, and security, reflecting the term's broad usage across industries.