While I believe the design is technically possible, I see few issues:
800km still does not make the aircraft versatile enough for most airlines. It can only serve a limited number of routes, compared to the already lacklustre Q400, which has more than twice the range. Also see Dassault Mercure.
Fully draining the batteries will wear them out very quickly. Normally you should not drain them below 20%, leaving the rest only for reserve.
Charging them to 100% means a turnaround of at least 1.5 hours. Not ideal for scheduling or crew planning. Making 36 tonnes of batteries in the wing replacable on the stand is not realistic.