A vehicle power supply system includes a control contactor and at least first and second power contactors along a top side of a vehicle. The first and second power contactors receive different polarities of electrical power from an off-board power supply system to power the vehicle. The control contactor conducts a control signal indicative of whether the first and second power contactors are conductively coupled with the off-board power supply system. The first power contactor receives a positive polarity of the electrical power and the second power contactor receives a negative polarity of the electrical power while the vehicle has a first orientation relative to the off-board power supply system. The first power contactor receives the negative polarity and the second power contactor receives the positive polarity while the vehicle has an opposite, second orientation relative to the off-board power supply system.