Disney expects you to park the
ECV inside your room, and charge it there when you are not using it.
Even folks who stay at the Value resorts, with the smallest rooms on the property, are expected to keep their
ECVs with them inside the room.
When you rent an ECV (or any type of medical equipment) it is your responsibility to keep it in your room, or your possession.
Remember to charge your ECV fully overnight, every night, and you shouldn't have any battery problems during the day - if you do, be sure to call your rental vendor as soon as you see a problem so they can swap either the battery or the entire ECV. (I recommend keeping your rental vendor's contact info in your cell phone just in case) Most folks have no problems, but I like to be prepared!
If you are planning on taking delivery in the morning, and then heading out for a full day at the Parks, be sure to ask your vendor to delivery the ECV with the battery fully charged so you don't have to worry.