NOVELTY - Zinc-bromine flowing electrolyte battery comprises: negative electrolyte pump; positive electrolyte pump; and complexed bromine located within positive electrolyte tank that is in fluid communication with positive electrolyte circulation path; where in use preferential activation of either of negative electrolyte pump or positive electrolyte pump determines whether positive electrolyte only or positive electrolyte and complexed bromine mix are circulated within positive electrolyte circulation path.    USE - As zinc-bromine flowing electrolyte battery (claimed).    ADVANTAGE - The zinc-bromine flowing electrolyte battery comprises improved bromine complex valve, as compared to prior art batteries which have positive electrolyte pump having inlet to only draw aqueous bromine electrolyte into positive electrolyte circulation path, and separate bromine complex pump is required to draw complexed bromine from bottom of positive bromine electrolyte tank and introduce it into positive electrolyte circulation path, which increases cost and complexity and reduces reliability and efficiency of battery. The bromine complex valve includes control mechanisms for controlling positive electrolyte and complexed bromine flow within positive electrolyte circulation path of battery. The positive electrolyte and complexed bromine flow control mechanisms operate to afford control over whether positive electrolyte pump will pump positive electrolyte only or positive electrolyte and complexed bromine mix into positive electrolyte circulation path. The control is achieved simply by choice of which of positive electrolyte pump or negative electrolyte pump is activated first. Thus the battery obviates need for third pump dedicated to pumping complexed bromine or dedicated electrically operated valve and so offers savings in manufacturing costs as well as enabling zinc-bromine flowing electrolyte battery to be more compact and have improved overall efficiency. Further savings are likely for consumer due to improved reliability of battery resulting from reduced complexity through dispensing with need for third pump and reducing amount of complex electronics required.    DETAILED DESCRIPTION - A zinc-bromine flowing electrolyte battery comprises: negative electrolyte pump to circulate negative electrolyte within negative electrolyte circulation path; positive electrolyte pump to circulate positive electrolyte within positive electrolyte circulation path; and complexed bromine located within positive electrolyte tank that is in fluid communication with positive electrolyte circulation path; where in use preferential activation of either of negative electrolyte pump or positive electrolyte pump determines whether positive electrolyte only or positive electrolyte and complexed bromine mix are circulated within positive electrolyte circulation path. The activation of pump(s) results in pressure actuated switching of electrolyte flow control mechanism. The electrolyte flow control mechanism comprises positive electrolyte intake and positive electrolyte/complexed bromine combined intake (255), and pressure actuated switching of electrolyte flow valve causes increased volume of flow through one with respect to other; and further negative electrolyte inlet and positive electrolyte inlet. The battery further comprises separate actuator (275, 320) in communication with floor of negative (260) and positive (305) electrolyte expandable chambers. Each actuator comprises cut away portion(s) to facilitate electrolyte flow, and at least one notch to receive complimentary face of locking bar that slidably engages with either of actuators to restrict movement. Each of cut away portions of respective actuators can be aligned with electrolyte flow aperture(s) (280, 325) for flow of positive electrolyte or positive electrolyte/complexed bromine mix. The preferential activation pumps cause influx of high pressure negative and positive electrolyte into the chambers respectively to expand chamber and cause movement of associated actuator, which causes actuator cut away portion to not be in alignment with its associated electrolyte flow aperture to prevent flow of positive electrolyte or positive electrolyte/complexed bromine mix through it, by causing locking bar to slidingly engage notch of stationary actuator. The mechanism further comprises electrolyte inlet that opens into chamber, and further actuator in communication, at first end, with floor of chamber, where second end of actuator is attached to inlet platform. The upper surface of inlet platform makes sealing engagement with positive electrolyte inlet, and lower surface of inlet platform contacts slidable sleeve. The sleeve comprises aperture(s) for ingress of positive electrolyte into associated flow tube. The flow tube is intersected by complexed bromine inlet, and is in fluid communication with positive electrolyte circulation path. The preferential activation of electrolyte pump in fluid communication with electrolyte inlet causes electrolyte to flow into chamber to force actuator in generally downwards direction and causes inlet platform to be displaced from positive electrolyte inlet to allow influx of positive electrolyte into positive electrolyte flow tube. The displacement of inlet platform causes slidable sleeve to be displaced such that aperture(s) are closed to electrolyte flow. The preferential activation of electrolyte pump not in fluid communication with electrolyte inlet causes inlet platform to be in sealing engagement with positive electrolyte platform and results in aperture(s) formed in slidable sleeve being open to ingress of positive electrolyte, which causes positive electrolyte to pass along flow tube to cause entry of complexed bromine through complexed bromine inlet. INDEPENDENT CLAIMS are included for the following:    (1) the electrolyte flow control mechanism for zinc-bromine flowing electrolyte battery; and    (2) regulating flow of complexed bromine in positive electrolyte circulation path of zinc-bromine flowing electrolyte battery involving: activating negative or positive electrolyte pump; and activating pump not activated, where choice of which of pump is activated first determines if positive electrolyte only or positive electrolyte and complexed bromine mix are circulated.    DESCRIPTION OF DRAWING(S) - The figure shows partial sectional view of positive electrolyte pump unit flow control mechanism in neutral position.    Positive electrolyte flow unit (200)    Positive electrolyte outlet (215)    Positive electrolyte valve control inlet (255)    Negative electrolyte chamber (260)    Bromine complex actuator (275)    Bromine complex aperture (280)    Bromine complex actuator notch (290)    First angled face of locking bar (295)    Positive electrolyte chamber (305)    Positive electrolyte actuator (320)    Positive electrolyte aperture (325)