A system for charging multiple power sources including a plurality of batteries. The system also including a plurality of diodes, each diode of the plurality of diodes electrically connected in series with at least a battery of the plurality of batteries, wherein each diode of the plurality of diodes restricts current flow into the plurality of batteries and the plurality of diodes permits current flow from the plurality of batteries. The system includes a bus element connecting the batteries in parallel, having a cross tie element having an engaged state and disengaged state. The bus element disconnects a first battery from a second battery of the plurality of when the cross-tie element is in the disengaged state, and connects the first battery to the second battery when the cross tie element is in the engaged state. The system includes a load electrically connected to the plurality of diodes.