Even if that never happens,your eyes will be watering from the sulfuric acid vapor as it charges..if it could be vented to the outside,it would be an option..
I brought a spare car battery in my house a few weeks ago,so I could run a police scanner and a radio during a power outage after a Nor'easter,and I've been meaning to get it out of my room,because I can tell the acid odor is affecting my breathing (and its not even being charged)..
I put it in a plastic dish tub to avoid it ruining the rug too,because a battery will "sweat" and the condensation on it has traces of acid in it..that is why every old VW Beetle that had the battery under the back seat usually ended up dragging on the asphalt after some years,the acid rotted the floor pan away under it..