AG10 battery.Battery management system fault analysis methods and common fault case analysis

　　The battery management system (BATTERYMANAGEMENTSYSTEM), commonly known as the battery nanny or battery steward, is an important link between vehicle power batteries and electric vehicles. Its main functions include: real-time monitoring of battery physical parameters; battery status estimation; online diagnosis and warning; charging, discharging and Precharge control; equalization management and thermal management, etc. The main purpose of the battery management system (BMS) is to improve battery utilization, prevent battery overcharge and overdischarge, extend battery life, and monitor battery status.

　　The battery management system is not only closely related to the battery, but also has various connections with the vehicle system. Among all faults, compared with other systems, the battery management system faults are relatively high and difficult to deal with. This article summarizes some common methods for dealing with battery management system failures and case studies of common battery management system failures, for reference by relevant personnel of vehicle, battery, and management system manufacturers.

　　BMS fault analysis method

　　Observation

　　When communication interruption or control abnormality occurs in the system, observe whether there are alarms in each module of the system and whether there are alarm icons on the display screen, and then investigate the resulting phenomena one by one.

　　Fault Reproduction Method

　　Vehicle faults occur under different conditions. If conditions permit, the fault should be reproduced under the same conditions as much as possible to confirm the problem point. Elimination method: When similar interference occurs in the system, each component in the system should be removed one by one to determine which part is causing the impact on the system.

　　substitution method

　　When a module has temperature, voltage, control, etc. abnormalities, swap the positions of modules with the same number of strings to diagnose whether it is a module problem or a wiring harness problem.

　　Environmental Inspection Act

　　When a system failure occurs, such as the system cannot be displayed, we should not rush to consider it in depth because we often overlook some details. First we should look at the obvious things: Is the power plugged in? Is the switch turned on? Are all the wiring connected? Maybe that's where the problem lies.

　　program upgrade method

　　When an unknown fault occurs after a new program is burned, causing system control abnormalities, the previous version of the program can be burned for comparison to analyze and handle the fault.

　　data analysis

　　When a control or related failure occurs in the BMS, the data stored in the BMS can be analyzed, and the content of the messages in the CAN bus can be analyzed.

　　Analysis of common fault cases

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

　　Possible Causes

　　Abnormal power supply, short circuit or open circuit in the wiring harness, and DCDC no voltage output.

　　troubleshooting

　　Check whether the external power supply to the management system is normal and whether it can reach the minimum operating voltage required by the management system. Check whether the external power supply has a current-limiting setting, resulting in insufficient power supply to the management system. You can adjust the external power supply to meet the requirements of the management system. Electrical requirements; check whether there is a short circuit or open circuit in the wiring harness of the management system, and 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 management system that supplies power to the entire system has a voltage output; if so If abnormal, the bad DCDC module can be replaced.

　　2. BMS cannot communicate with ECU

　　Possible Causes

　　The BMU (main control module) is not working and the CAN signal line is disconnected.

　　troubleshooting

　　Check whether the BMU power supply 12V/24V is normal; check whether the CAN signal transmission line has pins out or the plug is not inserted; monitor the CAN port data to see whether BMS or ECU data packets can be received.

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