POWER SUPPLY DEVICE

A positive electrode-side input terminal is connected to a first positive electrode-side battery terminal, a negative electrode-side input terminal is connected to a second negative electrode-side battery terminal, a first switch is connected between a first negative electrode-side battery terminal and a second positive electrode-side battery terminal, a second switch is connected between a second positive electrode-side battery terminal and a first connection point between the positive electrode-side input terminal and the first positive electrode-side battery terminal, a third switch is connected between the first negative electrode-side battery terminal and a second connection point between the negative electrode-side input terminal and the second negative electrode-side battery terminal, a positive electrode-side output terminal is connected to a line connecting the second switch and the second positive electrode-side battery terminal, and a negative electrode-side output terminal to a line connecting the negative electrode-side input terminal and the second negative electrode-side battery terminal.