The BMS can monitor the running status of the battery pack in real time. After diagnosing the above faults, it will send a warning to the vehicle controller through the communication harness, requesting the vehicle controller to deal with the fault. If the BMS judges that the fault has exceeded the set threshold, it can judge whether to directly disconnect the main circuit circuit to prevent high temperature, low temperature, overcharge, overdischarge, overcurrent, leakage, etc. from causing damage to the battery and personal. The fault processing mechanism of the battery system generally adopts the fault classification processing method, that is, different fault levels correspond to different processing methods.