Shares in GS Yuasa, the Japanese battery supplier for Boeing\'s troubled Dreamliner, plunged on Thursday after its power packs overheated or caught fire in Mitsubishi\'s electric and hybrid vehicles. The stock dropped 12.47 percent to at 386 yen in morning Tokyo trade after the automaker said late Wednesday that lithium-ion batteries made by a joint venture including GS Yuasa suffered malfunctions in at least two instances. No one was injured in the incidents which involved Mitsubishi\'s i-MiEV model, the world\'s first mass-produced electric car, and its Outlander PHEV, a plug-in hybrid electric vehicle. Neither of the cars involved had yet been shipped to customers. The automaker has asked 4,000 vehicle owners to avoid charging their cars pending an investigation into the overheating batteries, made by a venture including Mitsubishi Motors, Mitsubishi Corp. and GS Yuasa. GS Yuasa drew global attention over the worldwide grounding of Boeing\'s next generation aircraft in January after a battery on a Japan Airlines 787 caught fire and forced an ANA flight to make an emergency landing in a separate case. GS Yuasa has the contract for all Dreamliner batteries. Japanese authorities have said they had found no major problem on the company\'s production line making batteries for Boeing\'s planes. But the problems set off worldwide probes and led to the grounding of the next-generation aircraft. On Monday, Boeing said a test flight of its troubled 787 plane went according to plan, in its latest step towards returning the Dreamliner to service.