Systems and methods for managing flow batteries utilize a battery management controller (BMC) coupled between a flow battery and a DC/DC converter, which is coupled to an electrical grid or a photovoltaic device via an inverter. The inverter converts an AC voltage to a first DC voltage and the DC/DC converter steps down the first DC voltage to a second DC voltage. The BMC includes a first power route, a second power route, and a current source converter coupled to the second power route. The BMC initializes the flow battery with a third DC voltage using the current source converter until a sensing circuit senses that the voltage of the flow battery has reached a predetermined voltage. The sensing circuit may include a capacitor, which has a small capacitance and is coupled across each cell of the flow battery, coupled in series between two resistors having very large resistances.