Patent ID: 8862365

Claim:
A vehicular power supply device mounted on a vehicle equipped with an idle stop function of stopping an engine when conditions for stopping the engine are met and starting the engine by operation of a starting means when conditions for starting the engine are met, the vehicular power supply device comprising: a generator connected to the engine, for generating a DC voltage; a voltage converter for converting the DC voltage output from the generator into a first DC voltage control value and outputting the value; a battery connected between the generator and the voltage converter; an electrical load including the starting means, supplied with a current and a voltage by way of the voltage converter; a lead battery charged with the output from the voltage converter, for supplying a current to the electrical load; and an idle-stop determination unit for determining whether or not the engine is in an idle stop state; wherein when the idle-stop determination unit determines that the engine is in the idle stop state, the voltage converter outputs, depending on the current and the voltage supplied to the electrical load, a DC voltage control value that is a target output voltage for the lead battery and higher than the first DC voltage control value.