Why there is no over-discharge protection with the BMS ?

A. Check whether C- wire was soldered correct or not . If the B- and C- wires are welded reversely, the protection board has no charge-discharge protection function;

B. There will be no discharge protection for the BMS with different charge and discharge port if user connects C- as the negative of charge and discharge .

C. The discharge Mosfet was broken (After disconnect the BMS with Battery , please measure the resisntance between B- and P- , if the resistance value is infinie with unit of M or above , it means the discharge mosfet is normal , however if the resistance value between them with unit of Ω and K ,it means the MOS tubes was broken). The common reasons for the damage of the BMS discharge MOS are: 1. The loader, especially the high-power discharge cabinet, which produce a high negative voltage between P+ and P- while the bms acting overdicharge protection (the P- terminal voltage is tens of volts higher than the P+ terminal), which would leads to the broken of discharge MOS from this high voltage. ; 2. The current is greater than the maximum current that the discharge MOS of the protection board can withstand, which caused over-heating problems with discharge mosfet .

D. The protection board discharge protection control circuit or the discharge MOS drive circuit is damaged.