Another organic AORFB has been demonstrated methyl viologen as anolyte and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl as catholyte, plus sodium chloride and a low-cost anion exchange membrane to enable charging and discharging. This MV/TEMPO system has the highest cell voltage, 1.25V, and, possibly, lowest capital cost ($180/kWh) reported for AORFBs. The water-based liquid electrolytes were designed as a drop-in replacement for current systems without replacing existing infrastructure. A 600-milliwatt test battery was stable for 100 cycles with nearly 100 percent efficiency at current densities ranging from 20 to 100 mA/cm, with optimal performance rated at 40–50mA, at which about 70% of the battery's original voltage was retained. The significance of the research is that neutral AORFBs can be more environmentally friendly than acid or alkaline AORFBs while showing electrochemical performance comparable to corrosive acidic or alkaline RFBs. The MV/TEMPO AORFB has an energy density of 8.4Wh/L with the limitation on the TEMPO side. The next step is to identify a high capacity catholyte to match MV (ca. 3.5M solubility in water, 93.8Ah/L).