A home energy expert, from not-for-profit energy group Ebico, replies: Fundamentally, this depends on the battery type, its capacity and its age (and efficiency).
The other major factor in this is the electricity tariff used and its cost. Electricity supplied through an Economy 7 tariff (which has two distinct peak and off-peak rates) will cost less than a standard rate tariff for an overnight charge.
How much does it cost to charge an electric car and how many times a week would I need to do it?
Looking at the major manufacturer’s vehicles, a full overnight charge would cost around £1.50 on Economy 7, whilst a charge (irrespective of day or night) on a standard tariff would cost about £3.40. For one full charge like this, electric cars can travel between 60 and 120 miles, depending on the model.
The choice of electricity tariff-type is, however, not as simple as it appears as any electricity used outside the off-peak period on Economy 7 is much more expensive than a standard rate.
So it’s important to consider carefully how much electricity is used in your home during the daytime before deciding which type of tariff (i.e. normal or Economy 7) is cost effective for you.
For comparison, purely in terms of ‘fuel’ cost, a small electric car costs about 1.4p per mile compared to around 9.5p for a diesel car of a similar size.
Read more: http://www.thisismoney.co.uk/money/experts/article-2258501/How-does-cost-charge-electric-car.html#ixzz2HeaF7jbv