To enable affordable and environmentally friendly eletrical energy storage, a battery was designed using sea-water as electrolyte. The performance of this battery was tested through repeated cycling under a variety of circumstances. The Coulombic and energetic efficiency were around 80% and 68% respectively. The battery saw a strong drop in performance after ~60 cycles. This was corroborated with results gained from four separate cells. Efforts to model the battery were limited by the accuracy of the utilized model itself.