Re: Battery cars are impractical
@AC
"Really? Is there somewhere I can read about it or is it hush hush?"
It's not hush hush at all and is well known in the industry. The following link talks about one such initiative, which involves working out who should get the available electricity and how to charge as many cars as possible to the greatest extent possible.
http://www.technologyreview.com/view/524866/the-coming-problem-with-electric-cars-how-to-charge-them-all/
However, you will also note they don't think it will necessarily work, as it requires people to have predictable journeys. Might be OK for some, but not for many. This also talks mostly about power supply rather than distribution, but the same sorts of ideas are being used for distribution. Accept you can't charge all the cars fully, so you try and determine what each car needs for the next days driving.
You choose you use Economy 7 heating as a comparitive load, but fail to realise that most local loops never allowed for widespread installtion of Economy 7!! If every house on a local loop had Economy 7 installed, you would get the same problem!! Economy 7 was a relative fad for a while and was generally installed across estates, where the local loop was beefed up to allow for it, but this was a very small amount of the housing stock, so doesn't apply to most houses/flats.
I agree that where Economy 7 was allowed for in the original local loop, then provided you don't want to use a fast charger, you should be OK. However, this isn't a typical local loop install.
I suggest you do some searching on google and there are plenty of articles dealing with this sort of problem. This is especially true of some areas of London where there is no ability to get more power into whole areas, let alone streets or individual houses. Big business in London is beginning to feel this.