The joint US-Japanese team, which is investigating into the Boeing Dreamliner’s battery problems, has shifted from the battery-maker to the manufacturer of a monitoring system.

Japan Transport Ministry official Shigeru Takano on Monday said that the probe into battery-maker GS Yuasa was over for now as no evidence was found relating to the source of the problems.

Ministry officials said as part of the ongoing investigation they will be inspecting Kanto Aircraft Instrument Co. that makes a system that monitors voltage, charging and temperature of the lithium-ion batteries.

All 50 of the Boeing 787s in use around the world have been grounded after one of the jets operated by All Nippon Airways made an emergency landing in Japan earlier this month due to overheating of the main battery.

Earlier in January, a battery of ANA’s 787 Dreamliner caught fire while parked at Boston’s Logan International Airport.

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GS Yuasa shares jumped after news of shifting of the probe to the system maker, gaining nearly 5 per cent in Tokyo trading. The scrip had plunged 12 per cent after the battery problems surfaced in Japan.

Ministry officials stopped short of saying that Kanto’s monitoring system was under any special scrutiny, saying it was part of an ongoing investigation.

“We are looking into affiliated parts makers,” Takano said.

Kyoto-based GS Yuasa declined to comment, noting that the investigation was still underway.

The Boeing 787 is the first jet to make wide use of lithium-ion batteries, the kind usually found in laptops and other gadgets. They are prone to overheating and require additional systems to avoid fires.

Investigators have been looking at the remnants of the ANA flight’s charred battery, but it is unclear whether the battery or a related part was behind its overheating.

Deliveries of the Dreamliner were three years behind schedule because of manufacturing delays. Much of the aircraft is made by outside manufacturers, many of them major Japanese companies who make about 35 per cent of the plane.

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