NEW : Japanese authorities say battery experienced a sudden drop in voltage . U.S. aviation officials evaluating data as part of investigation of 787 problems . Those batteries are used to power electrical systems , especially when the plane 's engines are idle . Dreamliners were grounded last week after fire in Boston , another incident in Japan . Comment:
NEW : Japanese authorities say battery experienced a sudden drop in voltage . U.S. aviation officials evaluating data as part of investigation of 787 problems . Dreamliners were grounded last week after fire in Boston , another incident in Japan . Comment: