Old School Tech has released a new article in its ground solar series, this time about the batteries. Originally intended to only run a freezer, we were able to also run two refrigerators off this system, but only for about four hours per night. One of the missions of the nightwatch during the hurricane power outage was to schedule operation of the power system, and monitor the batteries to their 50% depth of discharge. By experimentation, we determined that, under this load, 50% depth of discharge was approximately 24 volts, which would be about 24.5 volts at no load and with the surface charge dissipated. It was very easy to integrate this new task into the nightwatch routine. A future article will discuss an optimized version of this system based on lessons-learned.