The National Transportation Safety Board determined the voltage from the battery had not exceeded its capacity during the Jan. 7 incident at Boston's Logan International Airport. The New York Times reported.
The battery aboard the Japan Airlines 787 caught fire after passengers had deplaned.
Battery issues caused an All Nippon Airways 787 to make an emergency landing in Japan last week. After that, Dreamliners worldwide were grounded pending an investigation.
The Times said Japanese authorities had suggested overcharging the battery could cause it to overheat. The flight data recorder aboard the Boston jet, however, showed the charge did not exceed the 32-volt design capacity.
Japanese and U.S. investigators, as well as Boeing technicians, will continue pouring over the components to the battery-charging system, officials said.