A system for balancing energy delivery devices within the one or more battery packs and for providing isolated monitoring of the battery packs includes at least one group of energy delivery devices electrically connected in series. For each group of energy delivery devices, the system includes a balancing circuit for each adjacent pair of energy delivery devices. The balancing circuit adjusts charge stored in each energy delivery device of the pair so that the charge stored in the energy delivery devices of the pair is substantially equal, and the charge stored in each energy delivery device remains above a threshold. The system also includes a voltage monitoring module for sequentially selecting each of the energy delivery devices and providing a voltage associated with the selected device at an output port. The voltage monitoring module uses a low on-resistance differential multiplexer to select each of the energy delivery devices.