POWER SOURCE SYSTEM FOR VEHICLE

A power source system may include a main power source, a power converter including a capacitor, a relay configured to switch between connection and disconnection between the power converter and the main power source, an auxiliary power source, a boost converter having a low voltage terminal thereof connected to the auxiliary power source, and having a high voltage terminal thereof connected to the power converter without interposing the relay, and a controller configured to pre-charge the capacitor prior to placing the relay in a connected state. The controller may be configured to specify a relationship between a voltage and a current of the auxiliary power source based on data of chronological changes of the voltage and the current of the auxiliary power source, and control the boost converter based on the relationship such that a voltage of the auxiliary power source does not fall below a predetermined voltage threshold.