|Two lithium-ion car batteries produced by GS Yuasa, the same Japanese company that supplies batteries for the grounded Boeing 787 jetliner fleet, have overheated in recent days.
Mitsubishi Motors said Wednesday that a lithium-ion battery for its i-MiEV electric car caught fire at an assembly plant on March 18. Three days later, a battery in a plug-in hybrid Outlander car overheated and showed signs of melting.
No one was injured in either incident, Mitsubishi Motors said. It did not issue any recalls but said it would halt production and sales of the two models while it investigated the battery troubles. It also advised owners of the Outlander plug-in hybrid to drive only on gasoline mode for the time being.
ďFirst we need to clarify the cause,Ē Ryugo Nakao, the head of product and strategy development at Mitsubishi Motors, said at a news conference in Tokyo.
Mr. Nakao stressed that the plane and auto batteries were ďstructurally different.Ē
And Marc Birtel, a Boeing spokesman, said in a statement that the aircraft maker had been assured ďthat the battery in question is fundamentally different from the 787 battery both in its construction processes, design, and chemistry.Ē
GS Yuasa, one of Japanís biggest battery manufacturers, makes hybrid and electric vehicle batteries with Mitsubishi at a factory in Shiga in central Japan. The batteries GS Yuasa supplies to Boeing are manufactured at a different plant in neighboring Kyoto, where the battery maker has its headquarters.
While both the car and plane batteries use lithium-ion technology, their structures and composite materials are different. The GS Yuasa batteries aboard the 787 use lithium cobalt oxide, an older technology. The batteries in Mitsubishi Motorsí electric and hybrid vehicles use lithium manganese oxide.
On March 18, a battery aboard an electric vehicle, the iMiEV, being assembled at a Mitsubishi Motors plant in western Japan overheated and its casing caught fire, the automaker said. Workers had been conducting charging test on the vehicle, it said.
Three days later, a representative at a dealer just outside Tokyo charged a plug-in hybrid Outlander but the car would not start, Mitsubishi Motors said. The representative then detected a strange smell, checked under the hood and found that part of the battery casing had melted.
The battery problems come as a blow to Mitsubishi, whose sales of electric and hybrid vehicles have been disappointing. Since iMiEVís debut in 2009, Mitsubishi has shipped about 30,000 of the bubble-shaped electric vehicles worldwide. The model is known as the Mitsubishi I overseas. Mitsubishi has sold about 4,000 Outlanders, predominantly in Japan.
The fresh incidents of overheating could be an even bigger blow to GS Yuasa. Its batteries have come under scrutiny by both American and Japanese air safety regulators in January after one caught fire on a parked 787 in Boston, while another overheated during a flight over western Japan.
Boeing is in the midst of testing a redesigned battery system. It is hoping to complete those tests within the next week, a step toward persuading regulators to allow the planes back in the air. Still, neither the company nor regulators have pinned down the cause of the overheating in the 787 batteries.