A battery assembly includes a first plurality of battery cells, a second plurality of battery cells, and a switch between the first plurality of battery cells and the second plurality of battery cells. In an example, the first plurality of battery cells, the switch, and the second plurality of battery cells are connected in series to a load. In an example, the first plurality of battery cells, the second plurality of battery cells, and the switch are within an enclosure, which is within a pressure regulated section of an aircraft. The load may be external to the enclosure. The battery assembly further includes a controller configured to open the switch and the disconnect the first plurality of battery cells from the second plurality of battery cells, in response to an air pressure proximal to the first and second pluralities of battery cells falling below a threshold level.