A system comprising a series of at least two benthic microbial fuel cells (BMFC), wherein each BMFC comprises an anode electrically connected to a cathode, and wherein for each BMFC there is a first and second comparator configured to monitor BMFC voltage to determine if the voltage falls below one of two present thresholds. The output of the first comparator is electrically connected to the BMFC via a switch and the output of the second comparator is electrically connected to a pulse width monitor (PWM) block via a switch. A DC/DC converter is electrically coupled to each BMFC and configured to transfer energy stored in each BMFC to a battery, wherein the DC/DC converter is driven by the PWM block.