TOKYO -- Mitsubishi Motors Corp. has pinpointed the cause of the lithium ion battery glitch that forced it to halt production of the Outlander plug-in hybrid crossover and most i electric cars.
Mitsubishi said a small number of the affected i EVs were on the road in the United States and Europe and that drivers there had been notified not to drive them. The plug-in hybrid Outlander is sold only in Japan.
Customers overseas and in Japan were offered alternative vehicles while their EVs are out of action, spokeswoman Namie Koketsu said. Owners of the plug-in hybrid Outlander were instructed to turn off hybrid and EV-drive mode.
The hybrid owners will be compensated for the additional gasoline usage, Koketsu said. But if they make a request, they also will be given alternative vehicles until the fix is made.
Mitsubishi aims to file a recall in Japan next month for the Outlander plug-in hybrids and i EVs after it determines how to remedy the battery problem, Koketsu said today.
The company has not determined what callback actions to take for overseas markets. Mitsubishi has already informed the National Highway Traffic Safety Administration of the measures being taken so far in the Japanese market, Koketsu said.
"We have already contacted users through their dealers, in Japan and overseas, to assure their safety," she said.
About 4,000 Outlander plug-ins have the potentially defective batteries. There are about 100 affected i EVs in Japan and about 50 affected i EVs overseas, including in the United States and Europe. Mitsubishi did not break down the overseas numbers but said that most of the i EVs were in Europe.
Mitsubishi stopped production of the vehicles,as well as Japanese sales, last month after one lithium ion battery melted at a dealership and another caught fire in an assembly plant.
The problem stems from microscopic contaminants being introduced to battery cells during a screening process used by the supplier during the batteries' manufacturing, Mitsubishi said. That defect can result in short-circuited cells.
The problem stretches back to December, when the new screening process was introduced at the manufacturing line. Excessive force exerted on the batteries during this screening could alter the internal shape of the battery and contaminate it.
Mitsubishi said the supplier, Lithium Energy Japan, has dropped the screening process in which the defects were introduced.
Mitsubishi and Lithium Energy are now devising an alternative process. The carmaker plans to issue a recall after it verifies the new method and a fix for the batteries, Koketsu said.
The Outlander plug-in hybrid is scheduled to arrive in the United States next year. Rooting out the problem will likely keep that launch on track, she said.
Blow to ambitions
Mitsubishi's announcement that it had found the problem came just a day after it recalled the Outlander plug-in hybrid in Japan for separate problems with its driver motors.
That callback affected 3,839 units. The problem was traced to software that controls the front and rear drive motors and possible glitches in the gasoline-electric vehicle's generator and front drive motor.
The snags are a blow to Mitsubishi, which is positioning electrified vehicles at the center of a push to rebrand itself as an eco-car leader. They also are a setback for the Outlander plug-in hybrid, which had enjoyed brisk sales in Japan and is the first vehicle showcasing Mitsubishi's new hybrid technology.
The Outlander plug-in hybrid went on sale in Japan on Jan. 24, and Mitsubishi sold 4,000 units until sales stopped last month.
The battery problems evoke those of the Boeing 787 Dreamliner, which had its global fleet grounded because of overheating lithium ion batteries. The Boeing and the Mitsubishi battery packs trace their origins to the same supplier.
Mitsubishi's were made by Lithium Energy Japan, a joint venture with Japanese battery maker GS Yuasa Corp. Boeing's batteries were made directly by GS Yuasa. The batteries were made at different plants and have different materials and designs.
Smoke and fire
The i EV problem occurred March 18, when a battery pack overheated in the inspection room of Mitsubishi's Mizushima assembly plant. The battery pack started smoking and eventually caught fire.
The Outlander problem occurred three days later, when a plug-in at a Yokohama dealership was being brought out for delivery to a customer. The car wouldn't move, and employees discovered that part of the battery pack had overheated and melted.
No one was injured in either incident.
The i and a commercial vehicle variant called the Minicab come in two trim levels. The upper trim, which gets a bigger, more-powerful battery, uses the Lithium Energy Japan power pack. The lower trim uses a less-powerful battery made by Toshiba.
Mitsubishi has halted production only of the vehicles with the Lithium Energy Japan-made batteries. The Toshiba batteries apparently are fine.
Mitsubishi has continued to sell the i EV in the United States since the battery problem was discovered. That's because the cars in stock there contain batteries made before the problematic screening process was introduced in December. The limited number of affected i EVs in the United States received problematic batteries manufactured after December as replacement batteries, Koketsu said.
Mitsubishi has sold 15,000 i EVs since the car's debut in July 2009. About 1,500 were in the United States.
-- Reuters contributed to this report.