The goal of this study was to develop a power management system (PMS) that could power a submersible ultrasonic receiver (SUR) continuously to keep accurate time and listen to ultrasonic signals when there was enough energy for a complete scan. We developed a PMS and modified the hardware and firmware of the SUR to allow it to be controlled by our PMS. Thus, the SUR became optimized for the SMFC and was controlled by the PMS. The SUR switched to idle mode without stopping the RTC when there was not enough energy for a complete scan. The PMS used a 350-F capacitor to store microbial energy. The SMFC was deployed in the Palouse River, Pullman, WA. The integrated PMS was tested and operated the SUR continuously for six weeks. Our integrated PMS and sensor could make SMFCs a more viable renewable power source for continuous environmental monitoring. We found that the SUR could only be powered continuously if its operation was controlled by the PMS. We believe that future applications of more complex sensors could benefit from our novel approach of controlling the sensor using the PMS for uninterrupted operation even when the data are collected intermittently.