In a practical embodiment, one passive environmental management module or heat exchanger is provided for each bay in the stack. Component wise, one heat exchanger is provided as for each battery module. The heat exchanger has the same length and width dimensions as the rear panel of the battery module. The heat exchanger consists of the fins coupled to the third exterior wall which functions as a conductive panel. Within the internal volume, there is also provided a desiccant for moisture control. In a practical embodiment, the desiccant pack 56 is mounted to the third exterior wall 48 inside the heat exchanger. During maintenance when the heat exchanger is removed for inspection, the pack can be easily removed and replaced with a new one. A cover extends over the heatsink and includes on its front panel one aperture for each of the exhaust ports of the battery module. A gasket extends around the periphery of the front panel, and surrounds each aperture. When the battery module is plugged in, the internal space of the battery module is sealed to the internal space of the heat exchanger. The internal space of the battery module is in communication via the apertures to the internal space of the heatsink.