Battery power supply with electrically isolated control circuit

In a battery power supply apparatus for low-noise measurement systems or ultra high-sensitivity sensor elements (ultra-sensitive light or microwave sensors, or SQUID, SIS/SNS or other Josephson effect devices, etc.), the power supply device 8 that supplies power to the outside and the control device 6 that controls the power supply device perform bidirectional communications by means of an optical or accoustic communications circuit 7, and thus it is possible to prevent noise arising in the control device from reaching the power supply device. In addition, it is possible to prevent the introduction of noise from the optical or accoustic communications circuit into the power supply device within a shield case. Accordingly, it is possible to control the operation of the power supply device enclosed within the shield case from the control device outside of the shield case without having external noise affecting the power supply device. Moreover, based on commands from the control device, the power supply control device controls the battery control device and resistance control device, thus adjusting the current/voltage supplied to the outside from the power supply circuit of the power supply device and then, the startup/shutdown control device shuts off the supply of operating power, thereby eliminating noise generated by various functional blocks within the power supply device. Furthermore, the set states of the battery control device and resistance control device are maintained even after the operating power is shut off, so it is possible to continue the supply of battery power to the outside at the desired current/voltage settings at low noise.