POWER SUPPLY DEVICE AND BATTERY PACK CHARGING METHOD

The power supply device is provided with: a battery pack that comprises a plurality of battery units each of which includes a battery, a first terminal and a second terminal; a capacitor connected in parallel with the battery pack; and a current adjusting circuit that includes a load and a switching device for controlling a current to the load and adjusts a current from the capacitor to the battery pack. When a battery that has reached an upper limit voltage is detected during charging the battery pack, between control for closing a first path that connects the first terminal to the positive side of the battery and control for opening a second path that connects the first terminal to the second terminal and negative side of the battery, the power supply device causes the current to flow to the load to adjust the current flowing to the battery pack.