Electric-vehicle lithium-ion battery-pack costs fell 14 percent during the past year and are down 30 percent from three years ago because of technological improvements and increased production capacity, Bloomberg News reports, citing a study from its sister entity Bloomberg New Energy Finance.

EV battery costs fell to $689 per kilowatt hour (kWh) during the first quarter, down from $800 per kWh a year earlier. Bloomberg New Energy Finance also estimates that the battery industry has the capacity to supply as many as new 400,000 battery-electric vehicles this year, and that number may jump to almost 700,000 by the end of next year. Global vehicle makers sold about 43,000 EVs last year.

Lithium-ion battery costs are important because they can account for 25 percent or more of an EV's total costs, and estimates have varied widely. Last month, green-technology firm Pike Research estimated that lithium-ion battery costs may fall by about a third to $523 per kWh by 2017, while the battery pack for the Nissan Leaf EV has been reported to cost as little as $375 per kWh. The U.S. Advanced Battery Consortium has said battery costs will have to fall to about $150 per kilowatt hour for EVs to be price-competitive with conventional vehicles.