A device includes a transformer, a controller, and a switch coupled between the transformer and the controller. The transformer has a primary coil and a secondary coil. The controller receives an indication of a metric of a cell of a battery. In response to the indication, the controller outputs a signal to select a polarity of a balancing current for balancing the cell. The switch receives the signal from the controller. In response to the signal, the switch causes the transformer to generate a primary current of a selected polarity through the primary coil. The transformer generates the balancing current through the secondary coil by inductively coupling the primary coil to the secondary coil. The transformer outputs the balancing current having the polarity for balancing the cell.