Batteries in au Handsets Cause 3 Burn Injuries

Mar 31, 2008 16:46 Mami Akasaka, Tech-On!

KDDI Corp announced that it found a defect in the Li-ion rechargeable battery packs used in the W42K, a mobile phone for its "au" services.

The handset and the battery packs were manufactured by Kyocera Corp, and the battery cells were made by NEC Tokin Corp. The W42K was released in June 2006, and 214,349 units are in operation as of March 26, 2008. The battery packs subjected to recall are those shipped after May 2006.

"We have not yet been able to determine the exact number of affected battery packs," a KDDI spokesperson said.

The battery packs may overheat and blow up during use or charging and then they may emit smoke or break. KDDI received 13 complaints from users. The company was determined that three users suffered burns, the spokesperson said.

According to KDDI, the trouble occurred when an impact was applied to the battery pack, such as when it was hit by a pointy object. The internal insulating sheet was damaged by the collision, and the sheet function was deteriorated by the subsequent charging/discharging, thereby causing short-circuiting.

Also in June 2007, a defect was reported in battery packs containing a cell manufactured by NEC Tokin, which was packed by Kyocera. In this case, the defect was due to a problem in NEC Tokin's manufacturing process. This time, "the cause of the problem is still under investigation," an NEC Tokin spokesperson said.

"At the moment, the battery cell itself does not have any defect," the spokesperson said. "The trouble seems to have been caused by a combination of a number of factors, for example, a strong impact applied to the battery pack and charging/discharging repeated for many times."

NEC Tokin and Kyocera started the production of replacement battery cells/packs in February 2007 without being able to identify the cause of the problem. KDDI started recalling and replacing the battery packs in question from March 29, 2008.

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