Analysis of common failures of lithium-ion battery BMS (1)

　　1. The whole system does not work after power supply

　　possible reason

　　The power supply is abnormal, the wiring harness is short-circuited or disconnected, and the DCDC has no voltage output.

　　Troubleshooting

　　Check whether the external power supply of the management system is normal, whether it can meet the minimum operating voltage required by the management system, whether the external power supply is set to limit current, resulting in insufficient power supply of the management system; the external power supply can be adjusted according to the power requirements of the management system; check whether the harness of the management system Short-circuit or damage, modify the wiring harness to make it work normally; if the external power supply and wiring harness are normal, check whether the DCDC in the entire system power supply management system has a voltage output; you can replace the damaged DCDC module under any abnormal conditions.

　　2. BMS cannot communicate with ECU

　　possible reason

　　BMU (main control module) does not work, but the signal line is broken

　　Troubleshooting

　　Check whether the BMU power supply is 12V/24V normal; check whether the CAN signal transmission line is plugged in or unplugged; monitor the CAN port data to see if it can receive BMS or ECU packets.

　　3. The communication between BMS and ECU is unstable

　　possible reason

　　The external CAN bus is not well matched, and the bus branch is too long

　　Troubleshooting

　　Check whether the bus matching resistance is correct; whether the matching position is correct and whether the branch is too long.

　　4. BMS internal communication is unstable

　　possible reason

　　The communication line plug is loose, the CAN wiring is not standardized, and the BSU address is duplicated.

　　Troubleshooting

　　Check whether the wiring is loose; check whether the bus matching resistance is correct, whether the matching position is correct, and whether the branch circuit is too long; check the duplicate BSU address.

　　5. Insulation detection and alarm

　　possible reason

　　Leaking battery or drive. Insulation module connection failure.

　　Troubleshooting

　　Use the BDU display module to check the insulation test data, check the battery bus voltage, whether the negative bus voltage to ground is normal; the insulation resistance of the bus and the driver to the ground is measured with an insulation meter.

　　6. The main relay does not close after turning on the power

　　possible reason

　　The load detection line is not connected, the pre-fill relay is open, and the pre-fill resistor is open.

　　Troubleshooting

　　Use the BDU display module to check the bus voltage data, check the battery bus voltage, whether the load bus voltage is normal; check whether the load bus voltage rises during precharging.

　　7. The data of the acquisition module is 0

　　possible reason

　　The collection line of the collection module is disconnected, and the collection module is damaged.

　　Troubleshooting

　　Unplug the module again and measure whether the battery voltage at the connection of the collection line is normal, and whether the resistance value at the connection of the temperature sensor line is normal.