4" hole in front storage compartment floor

Does anyone know why there is a 4" circular hole in the front storage compartment of the floor in my 5th wheel? I found it when I took out the additional battery box that was screwed to the floor. There's plenty of openings for any spill to drain out and there's vents for any battery gas that's released so that's not the reason. I have no idea why this hole would be put there by the manufacturer. Excuse the poor picture. I couldn't get the flash on my camera to work.