11 common fault case analysis of battery management systems

　　Author ：Iflowpower – Portable Power Station Supplier

Battery management system, commonly known as battery nanny or battery housekeeper, is an important link to connect the car power lithium battery and electric vehicle. Its important functions include: battery physical parameters real-time monitoring; battery status estimation; online diagnosis and early warning; charge, discharge and precharge Control; equalization management and thermal management, etc. The battery management system is not only closely related to the battery, but also has a variety of links with the vehicle system.

In all faults, the faults of the battery management system are relatively high relative to other systems, but also difficult to handle. This paper summarizes some common methods for processing battery management systems and common faults of battery management systems, for reference, battery, and management system manufacturers. Common fault case analysis 1, the system is not working after the system power supply: the power supply is abnormal, the wire harness is short-circuited, the DCDC no voltage output.

Troubleshooting: Check whether the external power supply is normal to supply the management system, whether it can meet the minimum operating voltage required by the management system, see if the external power supply is limited, resulting in insufficient power supply to the management system. The external power supply can be adjusted to satisfy the power supply requirements of the management system; check if the harness of the management system has a short circuit or is a broken circuit, making it normal; the external power supply and harness are normal, then view the management system Whether the entire system powered DCDC has a voltage output; if there is an abnormal replaceable DCDC module. 2, BMS can't communicate with ECU: BMU (main control module) does not work, CAN signal line disconnection troubleshooting: Check if the BMU's power supply 12V / 24V is normal; check if the CAN signal transmission line is not plugged in; listening Can CAN port data that can receive BMS or ECU packets.

3, BMS and ECU communication unstable Cause: The external CAN bus matches, the bus branch is too long troubleshooting: the detection bus matches the resistance is correct; if the matching position is correct, the branch is too long. 4, BMS internal communication unstable Cause: Communication line plug loose, CAN line is irregular, BSU address has repeat. Troubleshooting: Detect whether the wiring is loose; the detection bus matches the resistance is correct, the matching position is correct, whether the branch is too long; check if the BSU address is repeated.

5, insulation test alarm possible cause: battery or drive leakage, insulation module detection line error. Troubleshooting: Use the BDU display module to view the insulation detection data, check if the battery bus voltage is normal, whether the ground voltage is normal; use insulated clockwatch to measure the busbar and drive to the ground insulation resistance. 6, the primary relay is not happening after power-on: the load detection line is not connected, the precharge relay is open, pre-charged.

Troubleshooting: Use the BDU display module to view the bus voltage data, check the battery bus voltage, whether the load bus voltage is normal; check whether the load bus voltage is rising during the pre-charge process. 7. Acquisition module data is 0 possible reasons: the acquisition module is disconnected, the capture module is damaged.

Troubleshooting: Re-pin the module wiring, measure whether the battery voltage is normal at the collected wire connector, measure whether the resistance value is normal at the temperature sensor line plug. 8. Battery current data error Possible cause: Hall signal line plug loose, Hall sensor damage, harvesting module damage.

Troubleshooting: Reploquately Pink the current Hall sensor signal line; check if the Hall sensor is normal, whether the signal output is normal; replace the acquisition module. 9. The battery temperature difference is too possible: the heat dissipation fan plug is loose, cooling fan fault.

Troubleshooting: Re-plug the fan plug line; supply the fan separately, check if the fan is normal. 10, battery temperature too high or too low possible reason: heat dissipation fan plug loose, cooling fan fault, temperature probe damage. Troubleshooting: Re-plug the fan plug line; supply the fan separately, check if the fan is normal; check if the actual temperature of the battery is too high or too low; measure the internal resistance of the temperature probe.

11, SOC abnormal phenomenon: SOC varies greatly during system working, or repeatedly hopped between several values; in the system charge and discharge process, SOC has a large deviation; SOC has always displayed fixed value constant. Possible cause: current is not calibrated; the current sensor model and the host program do not match; the battery has no depth charge and discharge; the data acquisition module collects the jump, resulting in automatic calibration of SOC; two conditions: 1) reach overchard protection; 2) The average voltage reaches the XXV or more. Customer battery consistency is poor, and the second condition cannot be reached.

By displaying the remaining capacity and total capacity of the battery; the current sensor is not connected correctly; troubleshooting: Calibrate current in the touch screen configuration page; change the host program or replace the current sensor; a depth charge and discharge of the battery; replace the data acquisition module, The system SOC is manually calibrated. It is recommended that customers have a depth charge and discharge every week; modify the host program, adjust the "Average Voltage to XXV or more" according to the customer's actual situation XXV. Set the correct battery total capacity and remaining capacity; correctly connect the current sensor to work properly.

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