DETROIT, Michigan - A small General Motors-backed battery company in the US, Newark, is working on technology it hopes will increase the time a battery lasts in an electric vehicle on one charge.The company says that, in two to four years, it will have developed batteries capable of powering an electric car for as far as 320km.California-based Envia Systems CEO Dan Akerson said: "The company has made a huge breakthrough in the amount of energy a lithium-ion battery can hold. GM is sure the battery will be able to take a car 160km within a couple of years and, with some luck, could double that distance."I think we've better than a 50/50 chance of developing a car that will go to 320km on a charge - that would be a game-changer."NO COMPETITORSGM's Chevrolet’s Volt can manage about 60km on a charge but has a small petrol engine that generates power to keep the car going and recharge the battery on the move. Few competitors have electric vehicles that exceed 160km though Tesla Motor’s Model S can travel 480km but its larger battery and overall cost are its main drawbacks. Nissan’s Leaf and Ford electric Focus claim 120km, though like all battery cars this can vary with temperature, terrain and speed.Envia said its next-generation rechargeable lithium-ion cell hit a record high for energy density, a development which will affect the price of electric vehicles dramatically by halving battery prices."These little companies come out of nowhere, and they surprise you," Akerson said GM Ventures, the automaker's investment arm, put $7-million (the equivalent of about R57-million) into Envia in January 2011.