Connecting member, power supply device, electronic device, and system

A system comprising:

• a pair of bearings;
• a control portion;
• a power supply control portion;
• a first battery;
• a sensor;
• and
• a functional circuit,
• wherein the sensor is configured to output a potential difference between the pair of bearings to the control portion as a potential information,
• wherein the power supply control portion is controlled by the control portion and is configured to output any one of power of the first battery and power supplied from the pair of bearings to the functional circuit, and
• wherein the control portion is configured to control the power supply control portion to output power of the first battery when the potential information is information indicating any of a conductive state, an insulated state, and a state in which the potential difference is under a predetermined value and is configured to control the power supply control portion to output the power supplied from the pair of bearings when the potential information is information indicating a state in which the potential difference is greater than or equal to the predetermined value.