Fast charging for future cars

Oil is passé as fuel for cars. Electricity is in. And, electric cars on the anvil could charge their batteries in the time it takes to fill up at a petrol stop. A group of companies including Germany's BMW, Porsche and Siemens (SIEGY) say they have developed technology that could help make super-fast charging possible. They have started a 450 kW charging station that needs only three minutes to provide enough juice for a 100 kilometre (62 miles) drive. A full charge takes 15 minutes. Ian Ellerington, head of technology transfer at the Faraday Institution, said the technology is significantly better than what is currently available, even if there are major issues to resolve before it is put into widespread use. "450kW is substantially quicker than the Tesla superchargers (120kW), and would, in principle, be 10 times quicker than the rapid chargers that are currently widely available," he said. Long charging times are a major drawback of electric cars currently in the market. They slow down road trips and they are a major inconvenience for owners who cannot charge their cars at home. The next generation of chargers could help solve the problem. At 350-450kW, electric charging will take a time comparable to refuelling with conventional fuel, which will make long journeys in [electric vehicles] as practical as in cars using liquid fuels. More development work is needed to make 450 kW chargers a practical option, however. One major piece of the puzzle is building cars that can handle the increased power. There are no vehicles currently in the market that could accept this amount of power, and it will need the next generation of batteries to take advantage of the full capability. For the 450 kW charging project, BMW and Porsche designed cars specifically for the tests. Keith Pullen, a professor of energy systems at City, University of London, said that super-fast charging comes with other drawbacks. "If you charge a battery very quickly, it's less efficient [and] it actually damages the battery," he said. The technology could be useful in an emergency, but frequent use would cause a battery to wear out quickly. Engineers would need to solve another problem: super-fast chargers use a huge amount of power. Pullen said that a service station with 20 charging stations would use about six megawatts of power, the same amount as a typical small town. "This power has to come from somewhere and it has to come from the grid," he said. "You wouldn't be able to roll this out, there have to be major changes first. "Be that as it may, an evolution has come full circle with no carbon emission to be afraid of.