NOVELTY - The flowing electrolyte reservoir system (200) comprises a battery cell stack (205), an outer tank positioned beneath the battery cell stack, an inner tank positioned inside the outer tank and beneath the battery cell stack, a first pump positioned on top of the outer tank and adjacent to the battery cell stack, a second pump positioned on top of the inner tank and adjacent to the battery cell stack, and a raised lip. A positive electrolyte input port and a positive electrolyte output port of the battery cell stack are directly disposed above the outer tank.    USE - The flowing electrolyte reservoir system is useful for a flowing electrolyte battery such as a zinc-bromine battery, a zinc-chlorine battery and vanadium flow battery.    ADVANTAGE - The flowing electrolyte reservoir system can be economically, safely and efficiently manufactured with reduced size and weight and high robustness, and reduces the risk of electrolyte leaks.    DETAILED DESCRIPTION - The flowing electrolyte reservoir system (200) comprises a battery cell stack (205), an outer tank positioned beneath the battery cell stack, an inner tank positioned inside the outer tank and beneath the battery cell stack, a first pump positioned on top of the outer tank and adjacent to the battery cell stack, a second pump positioned on top of the inner tank and adjacent to the battery cell stack, and a raised lip. A positive electrolyte input port and a positive electrolyte output port of the battery cell stack are directly disposed above the outer tank. The inner tank is transversely positioned between opposite corners of the outer tank and beneath the opposite corners of the battery cell stack. The outer tank contains zinc electrolyte, and the inner tank contains bromine electrolyte and fits into a void of the outer tank. The outer and inner tanks are made of rotational molded plastic, share a common lid, and are complete, separable tanks. The raised lip is integral to an edge of the outer tank. A bottom surface of the inner tank is sloped toward an electrolyte collection region, and an upper part of the inner and outer tanks form walls of a cavity for a cooling structure. The walls of the cavity include a hole for mounting a cooling fan.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic top view of a flowing electrolyte reservoir system.    Flowing electrolyte reservoir system (200)    Cell stack (205)    Bromine electrolyte tank (210)    Zinc electrolyte tank (215)    Bromine electrolyte pump. (220)