POWER SUPPLY DEVICE OF ELECTRIC VEHICLE AND POWER SUPPLY METHOD FOR AUXILIARY MACHINE OF ELECTRIC VEHICLE

PROBLEM TO BE SOLVED: To provide a power supply device of electric vehicle in which the battery life can be prolonged by preventing deterioration of a specific battery cell group, and to provide a power supply method for the auxiliary machine of an electric vehicle.SOLUTION: The power supply device 51 of an electric vehicle 10 includes a battery 21 for supplying power to a motor and general electrical components (auxiliary machine) 52 from a plurality of battery cells connected in series, and a BMU 54 which divides the plurality of battery cells into a plurality of battery cell groups 63A-63D, and selects a battery cell group of higher charging rate as a specific battery cell group for supplying power to the general electrical components 52. A controller 86 included in the BMU 54 monitors the charging rate and use frequency of each of the plurality of battery cell groups 63A-63D that can supply power to the general electrical components 52, and selects a battery cell group having the highest charging rate and a use frequency less than a predetermined value as a specific battery cell group out of the plurality of battery cell groups 63A-63D.