I was hired to conduct a design review toward approval of an electric refit for a 172. The plans had merit, but where it lost traction was that for a half to an hour of flying, there would be a many hour recharge period. Either the aircraft would be out of service for most of the rest of the day charging, or it would be necessary to change out heavy battery packs multiple times; meaning owning several, and then inevitable damage to the airframe handling such a heavy weight in and out or around regularly. The time will come, but right now the investment in a costly aircraft which must sit idle and change hours per minutes of flying is difficult to justify for a working plane.