Battery management system fault analysis!

　　Author ：Iflowpower – Portable Power Station Supplier

BatteryManagementSystem, commonly known as battery babysitter or battery housekeeper, is an important link to connect the car power battery and electric car. The main functions include: battery physical parameters real-time monitoring; battery status estimation; online diagnosis and warning; charge, discharge Precharge control; equalization management and thermal management, etc. The battery management system (BMS) is mainly to improve the utilization of the battery, preventing battery prevention and over-discharging, extending battery life, monitoring battery status.

The battery management system is not only closely related to the battery, but also has various contacts with the vehicle system. In all faults, the faults of the battery management system are relatively high relative to other systems, and it is also difficult to process. Xiaobian summarizes some common methods for processing battery management systems and common faults of battery management systems, for use, battery, battery, management system manufacturers.

BMS Fault Analysis Method Observing method When the system is interrupted or controlled, it is an alarm, and there is alarm icon on the display. Fault Resequences The faults of vehicles under different conditions are different. When conditions allowed, the problem is confirmed as much as possible under the same conditions, and confirms the problem point.

When the rule is similar to the interference, the various components in the system should be removed one by one to determine which portion affects the system. Replacement method When a module is abnormal, the module position of the same strings is changed, and the diagnosis is a module problem or harness problem. When the system is faulty, if the system cannot be displayed, let's not Urgent considerations, because we often ignore some details.

First we should look at those things: if there is any power supply? Is the switch opened? Is all the wirings connected? Perhaps the root of the problem is here. Program Upgrade Act When there is an unknown failure after the new program is burned, it causes the system to control an abnormality, and can burn the previous version of the program to compare the analysis and processing of the fault. Data Analysis When the BMS controls or related faults, the BMS storage data can be analyzed, and the contents of the message in the CAN bus are analyzed.

Common fault case analysis 1. The whole system does not work after the system power supply may cause an abnormal power supply, and the wire harness is short or broken, and the DCDC has no voltage output. Troubleshooting Check whether the external power supply is normal, whether it can achieve 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; adjust the external power supply to meet the management system Electrical power requirements; check whether the harness of the management system has a short circuit or is a broken circuit, modify the harness, making it normal; the external power supply and harness are normal, then view the DCDC supplied to the entire system to supply the entire system DCDC; If there is an abnormality replaceable DCDC module.

2, BMS can not communicate with ECU (Master Module) does not work, CAN signal line disconnection troubleshooting check BMU's power supply 12V / 24V is normal; check if the CAN signal transmission line retreats or plug is not inserted; listen to CAN port Data, is it possible to receive a BMS or ECU packet. 3, BMS and ECU communication instability possible causes the external CAN bus matches, the bus branch is too long, the detection bus matches the resistance correct; if the matching position is correct, the branch is too long. 4, BMS internal communication instability may cause the communication line plug loosen, the CAN line is not standardized, the BSU address has repeat.

Troubleshooting Detection 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 causes battery or drive leakage. , Insulation module detection line error.

Troubleshoot Use the BDU display module to view insulation detection data, check whether 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, after power-on, the main relay is not absorbted in the cause of the load detection line, the precharger is open, the precharge resistance is open. 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, the acquisition module data is 0 possible causes for the acquisition module acquisition line to disconnect, collecting modules corruption. Troubleshooting Reploys the module wiring, measure whether the battery voltage is normal at the acquisition line connector, is normal to measure whether the resistance value is normal at the temperature sensor line plug. 8, battery current data error may cause the Hall signal line plug loose, Hall sensor is damaged, the acquisition module is damaged.

Troubleshooting Reploquest Carter Sensor Signal; Check if the Hall sensor is normal, whether the signal output is normal; replace the acquisition module. 9. The battery temperature difference is too large.

Cause Conditioning fan plug loosen, cooling fan failure. Troubleshooting reinterproces the fan plug line; supply the fan separately, check if the fan is normal. 10, battery temperature is too high or low may cause heat dissipation fan plug loose, cooling fan fault, temperature probe damage.

Troubleshooting 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. After relay operation, the system error may cause relay auxiliary contact disconnect line, relay contact adhesion troubleshooting reinterproving the harness; measure the auxiliary contacts in the multimeter.

12. You cannot use a charging machine to charge possible causes that the charging machine is not normal to troubleshoot the BMS communication to replace a charger or BMS to confirm whether the BMS fault or charging failure; check whether the matching resistance of the BMS charging port is normal. 13.

Inboard meter No BMS Data Display Possible Cause Main Control Module Wire Beam Connection Abnormal Troubleshooting Check if the main control module harness is connected, does it have a low-voltage working voltage of the car, whether the module works normal 14, some battery box detection data Loss may cause a variety of connections that can be in contact with poor contacts, or BMS slave module does not work hard to troubleshoot the contact case, or replace the BMS module;. 15. SOC unusual 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 numerical values.

Possible cause current is not calibrated; the current sensor model does not match the host program; the battery has no depth charge and discharge; the data acquisition module collects the jump, causing the SOC to automatically calibrate; two conditions for SOC calibration: 1) reach overcharge 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. .