Battery management system, commonly known as battery nanny or battery housekeeper, is an important link between vehicle power battery and electric vehicle. Its main functions include: real-time monitoring of battery physical parameters; battery state estimation; online diagnosis and early warning; charging, discharging and pre-charging control. Balance management and thermal management.
The battery management system not only has close contact with the battery, but also has various links with the whole vehicle system. Among all the faults, the fault of the battery management system is relatively high and difficult to handle compared with other systems.
This paper summarizes some common methods for dealing with battery management system failures and case analysis of common faults in battery management systems for reference by vehicle, battery, and management system manufacturers.
1. The entire system does not work after the system is powered.
Possible causes: abnormal power supply, short-circuit or open circuit, DCDC no voltage output.
Troubleshooting: Check whether the external power supply is normal to the management system, whether it can reach the minimum operating voltage required by the management system, and whether the external power supply has a limited flow setting, resulting in insufficient power supply to the management system.
The external power supply can be adjusted to meet the power requirements of the management system; check whether the wiring harness of the management system has a short circuit or an open circuit, modify the wiring harness to make it work normally; if the external power supply and wiring harness are normal, check the management system to give Whether the DCDC supplied by the whole system has a voltage output; if there is an abnormality, the DCDC module can be replaced.
2. BMS cannot communicate with ECU
Possible cause: BMU (master module) is not working, CAN signal line is broken
Troubleshooting: Check if the BMU's power supply 12V/24V is normal; check whether the CAN signal transmission line is retracted or the plug is not inserted; if the CAN port data is monitored, whether it can receive the BMS or ECU data packet.
3, BMS and ECU communication is unstable
Possible cause: The external CAN bus is poorly matched and the bus branch is too long.
Troubleshooting: Check if the bus matching resistor is correct; if the matching position is correct and the branch is too long.
4, BMS internal communication is unstable
Possible causes: The communication line plug is loose, the CAN trace is not standardized, and the BSU address is duplicated.
Troubleshooting: Check if the wiring is loose; check if the bus matching resistance is correct, if the matching position is correct, and if the branch is too long; check if the BSU address is duplicated.
5, insulation detection alarm
Possible causes: battery or driver leakage, insulation module detection line is wrong.
Troubleshooting: Use the BDU display module to view the insulation test data, check the battery bus voltage, and whether the negative bus to ground voltage is normal; use the insulation shake meter to measure the insulation resistance of the bus and driver to ground respectively.
6. The main relay does not pick up after power-on.
Possible causes: The load detection line is not connected, the pre-charge relay is open, and the pre-charge resistor is open.
Troubleshooting: Use the BDU display module to view the bus voltage data, check the battery bus voltage, and whether the load bus voltage is normal; check whether the load bus voltage rises during the precharge process.
7, the acquisition module data is 0
Possible cause: The collection module of the acquisition module is disconnected and the acquisition module is damaged.
Troubleshooting: Re-plug the module wiring, measure the battery voltage at the acquisition line connector, and measure the resistance at the temperature sensor cable plug.
8, battery current data error
Possible causes: The Hall signal cable plug is loose, the Hall sensor is damaged, and the acquisition module is damaged.
Troubleshooting: Re-plug the current Hall sensor signal line; check if the Hall sensor power supply is normal, the signal output is normal; replace the acquisition module.
9, the battery temperature difference is too large
Possible cause: The cooling fan plug is loose and the cooling fan is faulty.
Troubleshooting: Re-plug the fan plug cable; separately supply power to the fan and check if the fan is normal.
10, the battery temperature is too high or too low
Possible causes: The cooling fan plug is loose, the cooling fan is faulty, and the temperature probe is damaged.
Troubleshooting: Re-plug the fan plug wire; separately supply power to the fan, 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 anomaly
Phenomenon: SOC changes greatly during system operation, or repeatedly jumps between several values; in the system charging and discharging process, SOC has a large deviation; SOC always shows a fixed value.
Possible causes: The current is not calibrated; the current sensor model does not match the host program; the battery has not been deeply charged and discharged for a long time; the data acquisition module collects the hopping, resulting in automatic calibration of the SOC;
Two conditions for SOC calibration: 1) overcharge protection is achieved; 2) average voltage is above xxV. The customer's battery consistency is poor. When overcharged, the second condition cannot be reached. Check the remaining capacity and total capacity of the battery through the display; the current sensor is not connected properly;
Troubleshooting: Calibrate the current in the touch screen configuration page; change the host program or replace the current sensor; perform a deep charge and discharge on the battery; replace the data acquisition module, manually calibrate the system SOC, and recommend that the customer do a deep charge and discharge once a week; The host program adjusts the xxV in the condition that the average voltage reaches xxV or more according to the actual situation of the customer.
Set the correct total battery capacity and remaining capacity; connect the current sensor correctly to make it work properly.
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Shenyang Zhicheng Heavy Machinery Manufacturing Co., Ltd. , https://www.zhichengmachinery.com