Its not just the batteries and cars. Can the grid really handle the huge increase in demand ? How much investment needs to be done to upgrade it? How long will that take?
"The short-term impacts for most utilities should be minimal and localized. There is a possibility, however, of isolated impacts on some distribution transformers and secondary drops, particularly in neighborhoods with older distribution systems including underground systems."
http://et.epri.com/Communications_Potential_Impacts_of_Vehic...
Edit: added quote.