Hello Scott,
I am sorry to hear of your unexpected illness and hope this finds you recovering. While there are no lists of charging stations for Guests, using ECVs, I did find some fantastic articles you may want to consider reading which may aid in planning your upcoming visit.
First and foremost, Walt Disney World does rent ECVs on property and recommends a
list of participating local companies that you, yourself may be using, which can be beneficial if a problem arises with the ECV.
Allears.net has a very informative article for Guests called
Wheelchair/Scooter/ECV FAQ and touringplans.com has blog posts titled
Using and Electric Scooter (ECV) at Disney World and
Tips for Touring Disney World in an ECV or Wheelchair. While I can not provide a direct link to these sites, feel free to search and read these very informative articles. I think it will reassure you, it is very rare for an ECV to run out of battery life during the day. When stopped for a while, turn the vehicle off to reserve the battery life, each ECV typically has a very convenient gauge indicating what is left in the battery life and ECV's can be charge at any electrical outlets. If you happen to find your ECV battery is running low, feel free to ask a Cast Member if they could possibly point out an outlet for you to use, you may have to ask around but outlets can be found.
If I can be of any further pixie dusted assistance feel free to ask and may your upcoming stay at Walt Disney World be filled with many magical and memorable moments.
Amy M*o*