A vehicle power supply system provides redundant high-voltage and low-voltage power supply for an electric vehicle or a hybrid-electric vehicle. The power supply system includes first and second high-voltage battery units. A positive terminal of the first unit is connected to a positive power distribution arrangement and a positive terminal of the second unit is connected to a negative terminal of the first high-voltage battery unit via an intermediate power distribution arrangement, and a negative terminal of the second unit is connected to a negative power distribution arrangement. The system has a first bypass line connecting the positive power distribution arrangement with the intermediate power distribution arrangement, and a second bypass line connecting the negative power distribution arrangement with the intermediate power distribution arrangement.