Battery management system

A battery management system is electronics that monitor and control a battery pack’s operation and safety, including cell voltage, temperature, and current.

State of charge: The estimated fraction of a battery’s usable capacity remaining, usually expressed as a percentage. The system estimates remaining charge from measurements and models rather than directly measuring it.
Battery pack: An assembly of battery cells connected electrically and arranged to provide required voltage and capacity. The management system monitors the cells and controls operation at pack scale.
Electric vehicle: A vehicle propelled partly or entirely by electric motors powered by onboard electrical energy storage. Traction packs require monitoring across many cells under changing power and temperature demands.
Battery protection circuit: Circuitry that disconnects a battery when electrical conditions exceed defined safety limits. A protection circuit may provide cutoff functions, while a management system also monitors and coordinates pack operation.
State of health: An estimate of a battery’s condition relative to its original performance, often based on capacity and resistance. Health estimates help the system detect degradation and revise available capacity.
Battery cell: The basic electrochemical unit that stores and releases electrical energy. Cell-level measurements reveal imbalances and limits hidden by pack-level readings.
Lithium-ion battery: A rechargeable battery that moves lithium ions between electrodes during charge and discharge. Its cell limits and sensitivity to overcharge make active supervision essential.
Battery charger: A device that supplies controlled electrical energy to recharge a battery. The charger controls power delivery; the management system reports limits and may request charging changes.
Cell balancing: The process of reducing differences in charge among cells connected in a battery pack. Balancing prevents the weakest or most charged cell from limiting the whole pack.
Voltage sensor: A device or circuit that measures electrical potential difference. Individual cell voltage readings are among the system’s primary safety inputs.

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