We had a week of heavy rain once. What I found out was to put the poncho on but don't sit on it, drape the back of the poncho over the back of the seat. That way the rain doesn't drip down your back and onto the seat. You sort of make a tent of the poncho. Also if you pick up inexpensive ponchos at the dollar store before you go you can have an extra one to cover your ECV if rain is threatening if you need to leave the ecv outside an attraction. This also a good idea for strollers. I have used the shower cap idea after I got home with my power chair.