Battery management system failure analysis method and common fault case analysis

Battery management system (BATTERYMANAGEMENTSYSTEM), 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 Precharge control; balance management and thermal management. The battery management system (BMS) is mainly to improve the utilization of the battery, prevent overcharging and overdischarging of the battery, prolong the service life of the battery, and monitor the state of the battery.

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.

BMS failure analysis method

Observation

When the communication interruption or control abnormality occurs in the system, observe whether each module of the system has an alarm, whether there is an alarm icon on the display, and then check the obtained phenomenon one by one.

Fault recovery method

The faults of the vehicle under different conditions are different. When conditions permit, the faults are reproduced under the same conditions as much as possible, and the problem points are confirmed. Exclusion When the system has similar interference phenomena, each component in the system should be removed one by one to determine which part affects the system.

Replacement method

When a module experiences abnormalities such as temperature, voltage, and control, change the module position of the same number of strings to diagnose a module problem or a harness problem.

Environmental inspection

When the system fails, if the system can't display, we should not rush to consider it in depth, because we often ignore some details. First of all, we should look at the obvious things: If there is no power on? Is the switch turned on? Is all the wiring connected? Perhaps the root of the problem is there.

Program upgrade method

When the new program is burned, an unclear fault occurs, resulting in abnormal system control. The previous version of the program can be burned to compare and analyze the fault.

Data analysis

Battery management system (BATTERYMANAGEMENTSYSTEM), 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 Precharge control; balance management and thermal management. The battery management system (BMS) is mainly to improve the utilization of the battery, prevent overcharging and overdischarging of the battery, prolong the service life of the battery, and monitor the state of the battery.

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.

BMS failure analysis method

Observation

When the communication interruption or control abnormality occurs in the system, observe whether each module of the system has an alarm, whether there is an alarm icon on the display, and then check the obtained phenomenon one by one.

Fault recovery method

The faults of the vehicle under different conditions are different. When conditions permit, the faults are reproduced under the same conditions as much as possible, and the problem points are confirmed. Exclusion When the system has similar interference phenomena, each component in the system should be removed one by one to determine which part affects the system.

Replacement method

When a module experiences abnormalities such as temperature, voltage, and control, change the module position of the same number of strings to diagnose a module problem or a harness problem.

Environmental inspection

When the system fails, if the system can't display, we should not rush to consider it in depth, because we often ignore some details. First of all, we should look at the obvious things: If there is no power on? Is the switch turned on? Is all the wiring connected? Perhaps the root of the problem is there.

Program upgrade method

When the new program is burned, an unclear fault occurs, resulting in abnormal system control. The previous version of the program can be burned to compare and analyze the fault.

Data analysis

Battery management system (BATTERYMANAGEMENTSYSTEM), 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 Precharge control; balance management and thermal management. The battery management system (BMS) is mainly to improve the utilization of the battery, prevent overcharging and overdischarging of the battery, prolong the service life of the battery, and monitor the state of the battery.

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.

BMS failure analysis method

Observation

When the communication interruption or control abnormality occurs in the system, observe whether each module of the system has an alarm, whether there is an alarm icon on the display, and then check the obtained phenomenon one by one.

Fault recovery method

The faults of the vehicle under different conditions are different. When conditions permit, the faults are reproduced under the same conditions as much as possible, and the problem points are confirmed. Exclusion When the system has similar interference phenomena, each component in the system should be removed one by one to determine which part affects the system.

Replacement method

When a module experiences abnormalities such as temperature, voltage, and control, change the module position of the same number of strings to diagnose a module problem or a harness problem.

Environmental inspection

When the system fails, if the system can't display, we should not rush to consider it in depth, because we often ignore some details. First of all, we should look at the obvious things: If there is no power on? Is the switch turned on? Is all the wiring connected? Perhaps the root of the problem is there.

Program upgrade method

When the new program is burned, an unclear fault occurs, resulting in abnormal system control. The previous version of the program can be burned to compare and analyze the fault.

Data analysis

Battery management system (BATTERYMANAGEMENTSYSTEM), 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 Precharge control; balance management and thermal management. The battery management system (BMS) is mainly to improve the utilization of the battery, prevent overcharging and overdischarging of the battery, prolong the service life of the battery, and monitor the state of the battery.

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.

BMS failure analysis method

Observation

When the communication interruption or control abnormality occurs in the system, observe whether each module of the system has an alarm, whether there is an alarm icon on the display, and then check the obtained phenomenon one by one.

Fault recovery method

The faults of the vehicle under different conditions are different. When conditions permit, the faults are reproduced under the same conditions as much as possible, and the problem points are confirmed. Exclusion When the system has similar interference phenomena, each component in the system should be removed one by one to determine which part affects the system.

Replacement method

When a module experiences abnormalities such as temperature, voltage, and control, change the module position of the same number of strings to diagnose a module problem or a harness problem.

Environmental inspection

When the system fails, if the system can't display, we should not rush to consider it in depth, because we often ignore some details. First of all, we should look at the obvious things: If there is no power on? Is the switch turned on? Is all the wiring connected? Perhaps the root of the problem is there.

Program upgrade method

When the new program is burned, an unclear fault occurs, resulting in abnormal system control. The previous version of the program can be burned to compare and analyze the fault.

Data analysis

When the BMS is controlled or related to faults, the BMS stored data can be analyzed to analyze the contents of the message in the CAN bus.

Common fault case analysis

1. The entire system does not work after the system is powered.

Possible Causes

Abnormal power supply, short-circuit or open circuit harness, DCDC no voltage output.

Troubleshooting

Check whether the external power supply is normal to the management system, whether it can meet 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 management system. Electrical requirements; 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 whether the DCDC that supplies power to the whole system in the management system has voltage output; The abnormal DCDC module can be replaced abnormally.

2. BMS cannot communicate with ECU

Possible Causes

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 Causes

Bad external CAN bus, 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

The battery or driver is leaking, and the insulation module detection line is connected incorrectly.

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 shaker to measure the insulation resistance of the bus and the driver to ground.

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 Causes

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

Hall signal line plug is loose, 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 and the signal output is normal; replace the acquisition module.

9, the battery temperature difference is too large

Possible Causes

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 cable; 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, the system error after the relay action

Possible Causes

Relay auxiliary contact disconnection, relay contact blocking

Troubleshooting

Re-plug the harness; use a multimeter to measure whether the auxiliary contact is in the correct state.

12, can not use the charger to charge

Possible Causes

The charger is not communicating properly with the BMS.

Troubleshooting

Replace a charger or BMS to confirm if the BMS is faulty or the charger is faulty; check that the matching resistance of the BMS charging port is normal.

13, the vehicle instrument has no BMS data display

Possible Causes

The main control module harness connection is abnormal.

Troubleshooting

Check whether the main control module harness is fully connected, whether there is a normal low voltage working voltage of the car, and whether the module works normally.

14. Detection data loss of some battery cases

Possible Causes

Some parts of the vehicle may be in poor contact, or the BMS slave module may not work properly.

Troubleshooting

Check the connector contact or replace the BMS module.

15, 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 is not 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, suggest that the customer do a deep charge and discharge once a week; modify the host program, According to the actual situation of the customer, adjust the xxV in the condition that the average voltage reaches xxV or more. Set the correct total battery capacity and remaining capacity; connect the current sensor correctly to make it work properly.

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