Abstract: The balancing of the state of charge of a plurality of flow battery electrolytes is better achieved by a method for a battery having a plurality of flow battery stacks in series and supplied with electrolytes from at least two stores, in which the stacks each having a plurality of cells, the method including measuring and comparing the state of charge of the electrolytes of the respective stores and registering if the states of charge differ by more than a threshold and in the case of the state of the charge difference threshold being exceeded: controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes discharge through fewer cells than the more charged electrolytes and/or controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes are charged through more cells than the more charged electrolytes.

Abstract: Means for maintaining level complementary electrolytes inflow battery tanks has first and second interconnected tanks 2, 3. The first tank 2 contains positive electrolyte, 2b, and the second tank containing negative electrolyte 3b. Both tanks have a void 2a and 3 a respectively, for air or other noble gases. The tanks themselves are connected by pipes; a lower tank connecting pipe 4, an upper tank connection pipe 5 with an inter-pipe connecting pipe 6 therebetween. The peak of the lower tank connection pipe 4a is designed to remain below the normal liquid level 7 of both tanks, in contrast to the upper tank connection pipe 5 which remains above the desired liquid level 7.

Abstract: The balancing of the state of charge of a plurality of flow battery electrolytes is better achieved by a method for a battery having a plurality of flow battery stacks in series and supplied with electrolytes from at least two stores, in which the stacks each having a plurality of cells, the method including measuring and comparing the state of charge of the electrolytes of the respective stores and registering if the states of charge differ by more than a threshold and in the case of the state of the charge difference threshold being exceeded: controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes discharge through fewer cells than the more charged electrolytes and/or controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes are charged through more cells than the more charged electrolytes.

Abstract: Means for maintaining level complementary electrolytes inflow battery tanks has first and second interconnected tanks 2, 3. The first tank 2 contains positive electrolyte, 2b, and the second tank containing negative electrolyte 3b. Both tanks have a void 2a and 3 a respectively, for air or other noble gases. The tanks themselves are connected by pipes; a lower tank connecting pipe 4, an upper tank connection pipe 5 with an inter-pipe connecting pipe 6 therebetween. The peak of the lower tank connection pipe 4a is designed to remain below the normal liquid level 7 of both tanks, in contrast to the upper tank connection pipe 5 which remains above the desired liquid level 7.

Abstract: A redox flow battery 1 has a stack of individual cells, shown diagrammatically as a single cell 1, with anolyte and catholyte compartments 2,3 divided from each other by an ionically selective and conductive separator 4 and having respective electrodes 4,5. The battery has anolyte and catholyte tanks 6,7, with respective pumps 8,9 and a pipework 10, 11. In use, the pumps circulate the electrolytes An,Ca to and from the tanks 8,9, to the compartments 2,3 and back to the tanks. Electricity flows to a load L. The electrolyte lines are provided with tappings 21,22 via which fresh electrolyte F can be added and further tappings 23,24 via which spent electrolyte S can be withdrawn, the respective tappings being for anolyte and catholyte. On recharging, typically via a coupling 25 for lines 26 to all the tappings, a remote pump 27 pumps fresh anolyte and fresh catholyte from remote storages 28 and draws spent electrolyte to other remote storages 29.