I use an ecv and you'd be surprised how many times I charged my chair in outlets! They can add a great deal of range to a powerchair when you really need it.
I specifically remember charging my iPhone with 1% left in here. I grabbed a cinnamon roll, enjoyed the fireplace, and let that puppy charge up before heading off .
I don't think it would be to hard to have charging docks in all the costers. Have a way to use the kinetic energy that's created to power the outlets/USB ports. It would be a pretty awesome way to use the energy.