Patent ID: 8643335

Claim:
A power supply apparatus comprising: a plurality of power supply units which are connected in parallel; a positive polarity coupling portion in which positive polarity terminals of the power supply units are coupled together; and a negative polarity coupling portion in which negative polarity terminals of the power supply units are coupled together, wherein each of the power supply units is provided with: battery units; first relays connected in series to the battery units, capable of disconnecting electrical connection between the battery units and any one of the positive polarity coupling portion and the negative polarity coupling portion; resistor elements having one ends which are connected to the battery units between the battery units and the first relays, the first relays being connected to the any one of the positive polarity terminal and the negative polarity terminal of the battery units; a resistor coupling portion to which the other ends of the resistor elements are connected; and a second relay connected to the resistor coupling portion, capable of disconnecting electrical connection between the resistor coupling portion and any one of the positive polarity coupling portion and the negative polarity coupling portion which is connected to the first relays, the second relay having fewer in number than the number of the power supply units.