Power supply device and battery pack charging method

A battery pack charging method of charging a battery pack by a power supply device provided with a plurality of power storage units connected in series each of which has a battery, a first terminal, and a second terminal, the method performed by the power supply device, comprising:

• a voltage measurement step of measuring a battery voltage of the battery when the battery pack is charged;
• an upper limit voltage determination step of determining whether or not the battery voltage measured in the voltage measurement step has reached an upper limit voltage;
• a first path closing step of closing a first path in the power storage unit including a bypass target battery that is the battery having reached the upper limit voltage in a case where the battery voltage reaches the upper limit voltage in the upper limit voltage determination step;
• a capacitor current adjusting start step of controlling a switching device in a current adjusting circuit to cause a current to flow through a load;
• a second path opening step of opening a second path in the power storage unit including the bypass target battery after the capacitor current adjusting start step;
• and
• a capacitor current adjusting stop step of controlling the switching device to cut off the current flow to the load, wherein
• the power storage units each has the first path and the second path, the first path connecting a positive side of the battery and the first terminal, the second path connecting a negative side of the battery, the second terminal, and the first terminal,
• the power supply device includes a capacitor connected in parallel to the battery pack and the current adjusting circuit to adjust a current flowing from the capacitor to the positive side of the battery pack, and
• the current adjusting circuit includes the load through which the current flows and the switching device to control a flow and a cutoff of the current to the load.