POWER SUPPLY DEVICE

A power supply device includes a power generator, a drive source, a plurality of power supply lines, a plurality of batteries, a current value calculation part a demanded battery power calculation part and a power summation part The current value calculation part calculates the C-rates CR CR CR and CR of the batteries based on the charge levels of the batteries. The demanded battery power calculation part calculates a demanded power P or Q of the batteries based on the calculated C-rates CR CR CR and CR and the capacities of the batteries. The power summation part sums the demanded power P or Q of the batteries and power demanded by electrical loads. The control unit controls the drive source such that the power generator generates power calculated by the power summation part