Arcing may occur in a relay while the contact switching current is flowing through. High load, frequent operation, or relay aging are all likely to cause contact sticking, preventing contacts from properly disconnecting or closing, thus preventing the relay from correctly switching the circuit. Safety hazards such as circuit malfunction and equipment damage may be caused.

The application specifications of the relay should be strictly followed in the design to prevent relay failure in out-of-specification applications. Given frequent switching on and off of the OBC relays and possible unintended contact due to vehicle vibration, developers often design a detection circuit for contact status monitoring. The most common solution is to sample voltages at each end of the contacts and verify that the relay is in the expected idle state based on the voltage difference. However, as the OBC relays are located in the high-voltage section, additional high-voltage detection circuits will significantly increase the cost, so more cost-effective detection solutions are required.