Abstract: A redox flow battery 1 has a stack of individual cells, shown diagrammatically as a single cell, with anolyte and catholyte compartments divided from each other by an ionically selective and conductive separator and having respective electrodes. The battery has anolyte and catholyte tanks, with respective pumps and a pipework. In use, the pumps circulate the electrolytes to and from the tanks, to the compartments and back to the tanks. Electricity flows to a load. The electrolyte lines are provided with tappings via which fresh electrolyte can be added and further tappings via which spent electrolyte can be withdrawn, the respective tappings being for anolyte and catholyte. On recharging, typically via a coupling for lines to all the tappings, a remote pump pumps fresh anolyte and fresh catholyte from remote storages and draws spent electrolyte to other remote storages.