What Are The Five Protection Functions Of A Lithium-Ion Battery Bms?

A lithium-ion battery BMS features discharge overcurrent protection, short-circuit protection, overcurrent protection at 3A, and a 0.2-second delay.

1. Determining overcurrent and discharge status: In the smart battery charging and discharging state, if the detected current exceeds 3A and the 0.2-second delay still exceeds 3A, overcurrent is determined. At this point, the protection circuit cuts off the discharge protection switch. The protection condition is removed when the charger is connected. When the connected charger is detected, the overcurrent protection is removed; otherwise, the smart battery will remain in protection mode.

2. Determining overcharge and discharge conditions: If the battery voltage exceeds 4.2V or the total voltage exceeds 16.8V during charging, the battery is deemed to be in an overcharge state. At this point, the protection circuit cuts off the charging protection switch. In an overcharge discharge state, the voltage of each battery is less than 4V.

3. Determining overcharge protection failure: During charging, if the battery voltage exceeds 4.4V, the charging protection function is deemed abnormal. The secondary protection circuit is activated, and the three-terminal fuse is fused.

4. Determining over-discharge under-voltage and discharge conditions: During discharge, when the voltage of a cell falls below 2.5V, the battery is determined to be in an over-discharge state. At this point, the protection circuit will cut off the discharge switch to stop discharge. The release condition is that the voltage of all batteries is greater than 3V.

5. Determining over-temperature protection and release conditions: When the battery voltage temperature exceeds 55°C, the battery is determined to be in an over-temperature state. At this point, the protection circuit disconnects the charge/discharge protection switch. The release condition is when the battery temperature falls below 50°C.