Battery management system (BMS) is a technology that oversees a battery pack, an assembly of battery cells electrically arranged in a matrix configuration of rows by columns to provide a range of voltages and currents to a battery pack for an extended period under expected load conditions.
BMS are basically electronic control circuits that monitor and regulate the charging and discharge of batteries. The battery attributes to be monitored include the detection of battery type, voltages, temperature, capacity, state of charge, power consumption, remaining operating time, and charging cycles, amongst other characteristics.
The Benefits of Battery Management Systems
An entire battery energy storage system (BESS) could comprise tens, hundreds, or even thousands of lithium-ion cells strategically packed together, depending on the application and the type of mini-grid setup. These systems may have a voltage rating of less than 100V but could be as high as 800V, with pack supply currents ranging as high as 300A or more. Any mismanagement of a high-voltage pack could trigger a life-threatening, catastrophic disaster. Consequently, BMSS are absolutely critical to ensure safe operation.
The benefits of BMSS can be summarised as follows:
- Improves Performance: BMS battery pack capacity management, where cell-to-cell balancing is employed to equalise adjacent cells’ state of charge (SOC) across the pack assembly, allows optimum battery capacity to be realised. Without this BMS feature to account for variations in self-discharge, charge/discharge cycling, temperature effects, and general ageing, a battery pack could eventually render itself useless. In other words, the BMS can balance the cell voltages, ensuring the battery performs at its maximum potential. This can result in improved energy efficiency, longer runtimes, and increased reliability. Also, by optimising the battery’s performance, a BMS can reduce energy consumption and improve the system’s overall efficiency, resulting in cost savings and reduced environmental impact.
- Prolonged Life Span and Reliability: Battery pack protection management, electrical and thermal, ensures that all the cells are used within declared safe operating area (SOA) requirements. This delicate oversight ensures the cells are taken care of against aggressive usage and fast charging and discharging cycling and inevitably results in a stable system that will potentially provide many years of reliable service. In simple terms, a BMS ensures that the battery is charged and discharged safely and efficiently, preventing overcharging and over-discharging, which can damage the battery and shorten its lifespan.
- Enhances Safety: A BMS monitors the battery’s temperature, voltage, and current and can detect potential safety hazards such as overcharging, short circuits, and overheating. This can prevent accidents and protect the user and the surrounding environment at large.
- Diagnostics, Data Collection, and External Communication: A BMS provides valuable information about the battery’s performance, such as the remaining capacity, charging time, and health status. This can help the mini-grid developers to make informed decisions. Collectively, the BMS can be relayed to external devices and displays to indicate the resident energy available, estimate the expected range or range/lifetime based on current usage, and provide the state of health of the battery pack.
Off-Grid Solar Systems such as mini-grids rely on battery banks to store excess solar energy generated during the day for use at night or during periods of low sunlight. The application of this BMS system cannot be overemphasized as it guarantees improved system efficiency, provides user feedback, protects the battery, and ensures system safety.