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NTT DoCoMo recalls cell phone batteries

Exploding-battery problem hits cell market as Japanese mobile operator recalls lithium ion batteries used in some handsets.

NTT DoCoMo, one of Japan's largest mobile operators, said Thursday that it is recalling some of its lithium ion cell phone batteries used in its third-generation handsets because they could generate excessive heat that could short circuit the phone.

The company issued the recall for the D06 series batteries manufactured by Sanyo GS Soft Energy, a subsidiary of Sanyo Electric, through May 2006. The batteries were used in all FOMA D902i handsets and in some D902iS and D903i handsets. The issue could impact as many as 1.3 million handset batteries, according to an advisory the company released.

The problem is due to deformed electrode plates installed in the batteries, the company said. If the batteries are accidentally subjected to a strong external impact that results in a surface dent or similar depression, the deformed plates could pierce the batteries' internal insulation, resulting in an electrical short during, or right after, charging.

NTT DoCoMo confirmed that at least one D06 battery has ruptured due to the problem and that 17 other cases of D06 batteries overheating have been reported. The Mainichi Daily News reported that in one case the cell phone battery exploded and a user suffered burns. NTT DoCoMo supposedly noticed defects with the batteries after receiving complaints from customers in March, the Mainichi Daily News reported. But the article noted that NTT DoCoMo failed to announce the trouble and recalled batteries only in response to complaints on an individual basis.

All D902i handset owners will be mailed letters informing them that they will receive a replacement battery.

Owners of the D902iS and D903i handsets, which might use the faulty batteries, are also being contacted and asked to check if their batteries bear any of the specified three-letter codes: OKA, OLA, PAA, PBA, PCA, PDA or PEA. Replacement batteries will then be sent to users accordingly, NTT DoCoMo said.

Sales of the D902i, D902iS and D903i have been suspended for the time being.

Lithium ion batteries, which came out in 1990, have been used by many cell phone and notebook manufacturers because they can hold more energy than conventional rechargeable batteries and generally weigh less than traditional rechargeables. But a short circuit inside a lithium ion battery can cause the battery case to melt and spew hot liquids, or explode due to pressure and heat. Injuries caused by these defects have been reported around the globe.

This summer the problem impacted several notebook computer makers. In August Dell recalled 4.1 million notebook lithium ion batteries and Apple Computer recalled 1.8 million batteries because under certain conditions they exploded into flames. And in September Panasonic recalled 6,000 notebook batteries sold in Japan.