A power system includes a charge circuit connecting a low voltage circuit to a high voltage circuit; a charge control unit configured to execute an auxiliary charge control to charge a low voltage battery; a BCM configured to accept an ON operation or an OFF operation; and an auxiliary charge timing setting unit configured to set an auxiliary charge timing at which the auxiliary charge control is to be executed during a standstill period, the standstill period starting from acceptance of the OFF operation and ending at acceptance of the ON operation. If a soak time is shorter than an auxiliary charge-allowing period, the charge control unit executes the auxiliary charge control at the auxiliary charge timing set by the auxiliary charge timing setting unit, whereas if the soak time is longer than the auxiliary charge-allowing period, the charge control unit does not execute the auxiliary charge control.