POWER SUPPLY SYSTEM

The present invention relates to a power supply system (1) for cold crank functionality for a vehicle, comprising a switch control unit (15) for controlling a power switch (17) to switch an external load; an electronic unit (20); a first power supply (30) electrically connected to the switch control unit (15) to electrically supply the switch control unit (15); the first power supply (30) further electrically connected to the electronic unit (20) to electrically supply the electronic unit (20) in a normal mode; a second power supply (40); a switching unit (50) configured to electrically disconnect the first power supply (30) from the electronic unit (20) in a cold crank mode, when the voltage of the first power supply (30) drops below a threshold voltage; and electrically connect the second power supply (40) to the electronic unit (20) in the cold crank mode, the second power supply (40) is configured to supply the electronic unit (20) in the cold crank mode.