The invention provides a
relay fault detection method and device, a battery
management system and a medium. The method comprises the following steps: acquiring a current charging scheme and a current charging electrical stage; in each charging electrical stage, the following operations are executed: a
relay to be detected corresponding to the current charging electrical stage is determined according to a current charging scheme and a
battery pack-
relay circuit topological relation; for each to-be-detected relay, obtaining detection
voltage values at the two ends of the to-be-detected relay according to the circuit topological relation; and obtaining a fault detection result of the to-be-detected relay according to the detection
voltage value and an expected
voltage value of the to-be-detected relay in the current charging electrical stage. According to the invention, on the premise of satisfying the function safety voltage sampling ASIL C diagnosis coverage rate, the diagnosis robustness of the battery
management system is improved, and fault false alarms are reduced; and the position of the virtual connection sampling line can be accurately positioned, and the
troubleshooting difficulty is reduced.