TOKYO--Two incidents last month of lithium-ion batteries in
Japanese cars burning or melting ended a multiyear streak of safe
operation for the technology's use in cars, but not auto makers'
support for the power packs.
Japanese and U.S. car makers insist the safety record of
automotive lithium-ion batteries reflects years of cautious
development, despite the recent incidents in Mitsubishi vehicles
and Boeing Co.'s (BA) 787 Dreamliner fleet.
Mitsubishi Motors Co. (MMTOY, 7211.TO) said last month that a
lithium-ion battery pack for its i-MiEV electric car caught fire
while charging during a test inspection at the company's plant on
March 18. Three days later, the lithium-ion battery installed in a
hybrid Outlander overheated and melted the cell and part of the
battery pack when a new-car dealer tried to move the car.
According to the transport ministry, Japan has never before had
a problem with lithium-ion batteries overheating in cars shipped
inside the country.
Honda Motor Co. (HMC, 7267.TO), Nissan Motor Co. (NSANY,
7201.TO), Toyota Motor Corp. (TM, 7203.TO), General Motors Co.
(GM), and Ford Motor Co. (F) defended their use of the battery
technology.
"Honda has conducted plenty of safety tests and created safe
designs of its [lithium-ion battery technology]. There have been no
outbreaks of fire or burning incidents from the battery at Honda,"
a spokeswoman said. A Nissan spokesman added: "To date, more than
54,000 Nissan Leaf vehicles have been sold worldwide and all have
performed without serious incident."
GM and Ford, whose Chevrolet Volt, Ford Fusion, C-Max hybrids
and Focus Electric use lithium ion technology, say their batteries
are safe. Last year, the U.S. National Highway Traffic Safety
Administration said there was no evidence the Volt was prone to
catching fire after a probe of a fire in a vehicle whose battery
leaked fluid and short-circuited after a crash test. "We haven't
seen any issues experienced by others," said Ford spokesman Jason
Lasecki.
The batteries that caused problems at Mitsubishi were
manufactured by Lithium Energy Japan, a joint venture between
Mitsubishi Motors, Mitsubishi Corp. and GS Yuasa Corp. (6674.TO),
the same company that makes the lithium-ion batteries at the center
of Boeing's Dreamliner woes.
GS Yuasa spokesman Hiroharu Nakano said the battery design is
completely different from the one used on the Dreamliner and
manufactured at a different site. He said the three companies in
the venture have set up a joint team to investigate the cause of
the problems.
Battery experts say those incidents are the exception rather
than the rule. "Japanese auto makers have a long history in
developing batteries," said Akihiko Kido, director of the fuel cell
and electric-vehicle research division at the Japan Automobile
Research Institute, which helps set industry standards for
new-vehicle technology. "So the technology has been developed in
gradual increments over time."
Japan's auto makers have been at the forefront of the industry's
foray into hybrid and electric vehicles, a growing number of which
are installed with lithium-ion batteries.
Mitsubishi Motors' i-MiEV became the world's first mass-produced
electric car in 2009, followed by the Leaf from Nissan. Rivals
Honda and Toyota currently have four and three models,
respectively, that use lithium-ion batteries.
Toyota says it overcame an early skepticism of the technology.
"In the early stages, there was a strong feeling [within Toyota]
that it would be very difficult to use the lithium-ion battery in
cars," said Shoichi Kaneko, the engineer who was in charge of
Toyota's plug-in hybrid vehicle development.
To get comfortable with the technology, Mr. Kaneko said his
engineers "bullied" every part of the battery.
The engineers dropped a new battery from varying heights and
punctured a used one with a nail. Toyota built 750 test vehicles to
see how they behaved in real-life road scenarios over a cumulative
10 million kilometers (6.21 million miles).
Lithium-ion batteries for cars had to meet very different
specifications than for electronics like laptops, Mr. Kaneko said.
Car batteries have to operate in a much wider temperature range,
from below freezing to 122 degrees Fahrenheit, he said.
Electronic devices such as music players and computers aren't
used as hard or long as cars, said Mr. Kaneko. Toyota worked to
make its electric cars more aerodynamic, so they could operate
their target distance within their batteries' capacity.
Toyota engineers concocted a gamut of scenarios that pushed the
envelope. In one computer simulation, for example, engineers ran
the vehicle at top speed around a racetrack until it drained the
battery, then fully recharged it, and repeated that cycle for 24
hours before analyzing how the battery fared.
"We would think of such extreme scenarios that some people said,
"Would someone actually use the car this way?'" said Mr. Kaneko.
"But then someone else in the company would always say, "You can't
say for sure the possibility would be zero.'"
Toyota now uses lithium-ion batteries in its Prius plug-in
hybrid, Prius Alpha and the eQ.
But Mr. Kaneko said Toyota still plays it safe when evaluating
which lithium-ion battery technologies to use.
"There are still safety aspects [to other companies' batteries]
we are unable to fully grasp," he said.
--Mike Ramsey contributed to this article.
Write to Yoree Koh at yoree.koh@dowjones.com
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