System and method for charger contactor double weld detection

A vehicle comprising:

• charger contactors configured to selectively electrically couple positive and return terminals for connecting to a charger to corresponding terminals of a high-voltage bus;
• a precharge contactor configured to selectively couple a battery to the high-voltage bus through an impedance element;
• and
• a controller programmed to, at a start of a drive cycle, command the charger contactors to open and then command the precharge contactor to close, and, responsive to a difference between a first voltage measured across the positive and return terminals when the precharge contactor is closed and a second voltage measured across the positive and return terminals immediately prior to closing the precharge contactor being greater than a predetermined threshold, command the precharge contactor to open and command a main contactor coupled between the battery and the high-voltage bus to remain open to prevent connection of the battery to the high-voltage bus.

A method comprising:

• commanding, by a controller, charger contactors disposed between terminals for connecting to a charger to corresponding terminals of a high-voltage bus to open at a start of a drive cycle;
• commanding, by a controller, a precharge contactor that couples a traction battery to a high-voltage bus through an impedance to close for charging the high-voltage bus to a predetermined bus voltage;
• and
• commanding, by the controller, the precharge contactor to open and commanding a main contactor coupled between the traction battery and the high-voltage bus to remain open responsive to a voltage across the terminals for connecting to the charger changing from being less than a first predetermined voltage immediately prior to the precharge contactor being closed to being greater than a second predetermined voltage when the high-voltage bus is charged to the predetermined bus voltage.