Thats a Big Ol it Depends
For Example... I went on a buisness trip. My mechs despite sitting in a spot where they will not fall over or anything I still pulled the batteries just in case. My drip box 60 ( has had reports of auto fireing) no battery stays in that sucker. I like it but I do not leave it with a battery just in case.
My DNA 200s they stay with the connection as disconnection would require a soldering iron.
If leaving it powered up makes you a bit uncomfortable remove it if you can. I aint gonna give you a hard time for taking extra precautions.