Transport authorities probing the battery accident on an All Nippon Airways Co. Boeing 787 earlier this year began testing the grounded jetliner Monday at Takamatsu Airport.

The Japan Transport Safety Board will investigate how the battery system performs when subjected to conditions similar to those in place when the trouble occurred in January.

Four of the inspectors will start up the twin-jet's engines at Takamatsu Airport to check voltage and current flow to obtain detailed data, it said. No test flights are planned.

Meanwhile, Boeing Co. on Friday conducted its final test flight on a 787 Dreamliner with a new battery system as a part of a certification test for the U.S. Federal Aviation Administration needed to get the planes back in the skies.

Boeing 787s were grounded worldwide after the one operated by ANA made an emergency landing in Takamatsu on Jan. 16. The plane's lithium-ion battery under the cockpit was later found severely damaged and charred.