A modular auxiliary power module is described for a modular autonomous bot apparatus that transports an item being shipped. The modular auxiliary power module includes a base adapter platform, a cargo door, an auxiliary power source, and an output power outlet disposed on the base adapter platform as part of a modular component electronics interface. A top side of the base adapter platform has a cargo support area configured to support the item being shipped. Interlocking alignment interfaces (such as channels or latches) are on the top and bottom of the platform. The cargo door is movably attached to and extending from an edge of the base adapter platform, and the output power outlet is coupled to the auxiliary power source and provides access to power for other components of the modular autonomous bot apparatus from the auxiliary power source.