Hi!
The electric Skyhawk is planned to fly for 2 hrs, seat only two people, and be used almost exclusively for flight training. In flt training, most of the flights are out and back, and ususally .9-1.5 hour sorties.
The batteries will either be able to be recharged in the time it takes to debrief and brief a student, and/or they will be set up for a battery swap, which will take about 10" or so.
The electric motor, and associated accessories, are MUCH less weight than the comparable ICE equipment. The electric plane won't need the tanks and fuel. It, obviously, will need a battery. The solar cells on the wings, which won't be on the earlier models and/or will be an option, will help recharge the battery.
They picked the -172 because it is the most popular trainer. When you need to overhaul the ICE powerplant, you swap it out for the electric motor.
For those of you who feel it is a pipedream, there were many, many carriage and horse-type people who knew that the new "horseless carriage" would never take off: For example, they were too difficult to operate, they were loud, dirty and stinky, there was no where to drive them (not enough suitable roads), there was no where to maintain them, and there were no places to refuel them. Because of the lack of infrastructure, and the fact that it was a new technology, many, many people were 100% sure that the automobile would never take the place of the horse carriage.
cliff
KGRB