http://www.newscientist.com/article/dn19047-green-machine-recycled-batteries-boost-electric-cars.html

Life after death

There may be a more palatable version of this so-called vehicle-to-grid idea. Used lithium-ion batteries that no longer hold charge well enough to power a car could provide electricity storage for the grid, says Sankar Das Gupta at battery maker Electrovaya, based in Mississauga, Ontario, Canada.

Currently the car industry considers a battery to have reached the end of its life when repeat use means it can only be charged to 80 per cent of its original capacity. That would still be perfectly acceptable for grid-scale storage, says Das Gupta.

His company is involved in a project with partners including Eric Bibeau at the University of Manitoba in Winnipeg, Canada, in which they will combine used lithium-ion batteries from demonstration vehicles to build a 150 kilowatt-hour prototype storage system and monitor how it performs when connected to the grid.