Abstract: A battery preferably for use as a power source in an electrical vehicle includes a plurality of envelope separators for reducing the concentration of waste products at the surface of the battery plates. The envelope separators comprise two thin sheets of microporous material which are bonded together at their edges and placed between each of the plates of the battery. The envelope separators while being nonconductive are highly porous thereby allowing electrical current to pass from one plate to the other through the separators in the electrolytic solution of the battery. The electrolyte is pumped into each envelope separator under pressure and is forced out through the pores or small holes in the sides of the envelope to flush water, gas and loose particles of active material away from the plates of the battery.