On-board charging systems (OBCs) convert AC power from an external charging source into a DC voltage that is used to charge the battery pack in the vehicle. OBCs also perform other functions including charge rate monitoring and protection. Industry charging standards for OBC systems are shown in the table below. AC Level 2 OBCs and some Level 1 systems require isolation. With DC Fast Chargers, which plug directly into the quick charging connector, OBCs are bypassed.