An apparatus is provided that includes a plurality of serially-connected bypass circuits, a measurement/control element and a plurality of safety circuits. The bypass circuits are electrically connectable in parallel with a plurality of serially-connected batteries, each bypass circuit being connectable in parallel with a respective battery. The measurement/control element is electrically connected to the bypass circuits, and electrically connectable to the batteries; and the safety circuits are electrically connected to the measurement/control element, and electrically connectable between the measurement/control element and the batteries. The measurement/control element is configured to measure voltages across the respective batteries and, based on the voltages, selectively operate the bypass circuits to divert electrical current to or from the batteries through the respective bypass circuits. And each safety circuit is configured to limit current flow to the measurement/control element.