A:Answer in my set of 3, the "Parent" unit is plugged. The "Parent" unit is the one you have in the baby's room, or in my case the laundry room.
The other 2 units, or the monitors, have batteries. You are supposed to leave them plugged in routinely, but you can unplug them and carry them outside, to a different room, etc. Just remember to plug them back in when you are done.
