Lithium Battery BMS: Functions, Selection and Inverter Matching Tips

For photovoltaic energy storage and lithium battery pack assembly, the BMS acts as the protective brain of the battery and is indispensable.

The BMS has four core functions: real-time collection of the voltage and temperature of each cell to prevent overcharging, over-discharging, overcurrent and thermal runaway at high temperatures; reducing cell voltage difference through equalization circuits to avoid early protection of individual cells and capacity shrinkage of the whole battery pack; accurate calculation of SOC (State of Charge); and linkage communication with energy storage inverters via RS485.

There are two mainstream types of BMS on the market. Ordinary protection boards only provide hardware threshold protection without communication function. The inverter cannot obtain cell status data, and the battery is prone to locking after deep discharge and hard to wake up. Intelligent BMS with RS485 communication can transmit single cell voltage and temperature data to the inverter. The inverter will automatically adjust charging and discharging current, and support waking dormant batteries through mains power.

Common daily faults include inverter error alarms caused by reversed BMS communication wires or mismatched protocols, as well as drastically reduced battery life due to failed equalization and excessive cell voltage difference after long-term operation.

For energy storage battery assembly, prioritize 48V energy-storage-specific BMS equipped with RS485 communication and active equalization. Wire connection shall strictly follow pin definitions. Regularly check cell voltage difference to greatly extend battery service life.