A customer is recharging his wheelchair in my shop because the medical place down the street wouldn't let him. He offered to pay for the electricity, but I figure it's no different than customers charging their phones or laptops or plugging in their sewing machines, which was very common back when I had in store seating (the sewing machine thing less so since the fabric store across the street turned into a beauty salon, but I used to have people doing their homework for classes last minute).