Lithium-ion batteries brought an unexpected challenge with them when they arrived. They may weigh less, deliver more, charge faster, and last longer, but they can be unpredictable when they enter uncharted territory. A battery management system has become almost inevitable to prevent damage to user installations.
Such a system adds a brain to a cohort of lithium-ion batteries, otherwise potentially likely to go their own ways. Electronics monitor what is happening inside each cell. They are capable of shutting down single cells, or whole batteries, before these stray from safe operating margins. This simultaneously protects the battery, the application, and the user from harm.
The Primary Functions of Battery Management Systems
First and foremost, a lithium battery management system protects the cells and batteries on its watch. Its main job is to protect them from over- and under-charging, although it can also do several additional tasks, namely:
- Monitoring battery temperature and calculating the remaining charge.
- Monitoring battery safety by checking for loose connections and shorts.
- Balancing the charge across cells during charging to optimize performance.
If the battery management system detects an out-of-specification setting, it shuts the battery down, ceasing operation. This may inconvenience the user, although this is better than risking damaging the load.
How the System Delivers These Functions
The system monitors current flow, and calculates how much charge, and discharge a subject lithium battery can safely tolerate without damage. Current limit settings – and perhaps the load in the case of an inverter – shield the battery pack from these out-of-specification events, and involuntary over-heating.
Battery management systems come in many forms, and configurations. Some control overall systems, while others analyze data from individual lithium-ion cells. Protecting battery health makes good economic sense. Equally importantly, it helps prevent the flammable liquid electrolyte from overheating.
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