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Matsushita-made batteries could bust open Nokia cell phones

Lithium-ion batteries are giving more than just laptop makers constant headaches. Cell phone goliath Nokia today issued a product advisory for the Nokia-branded BL-5C battery warning consumers that the device could potentially experience overheating initiated by a short circuit while charging, causing the battery to dislodge.

As the cells in mobile phone batteries are smaller than those found in laptops, the risks are the same. Nokia told Engadget that the batteries will “overheat, expand, and pop out of the phone (due to the expansion of the battery).” The Finnish company said that no serious injuries or property damage have been reported.

Nokia has several suppliers for BL-5C batteries who have collectively produced more than 300 million BL-5C batteries. The estimated 46 million BL-5C batteries at fault are manufactured by Matsushita Battery Industrial Co., Ltd. of Japan between December 2005 and November 2006, from which there have been approximately 100 incidents of overheating reported globally. Nokia said that is working closely with Matsushita and will be cooperating with relevant authorities to investigate this situation.

Nokia is offering that all customers with affected BL-5C devices a replacement BL-5C battery free of charge. For a full list of affected phones and a form to check via product identification number, see Nokia’s website.

Battery recalls are a familiar thing for laptop makers, as over 10 million lithium ion laptop batteries have been recalled worldwide since last year. A long list of computer manufacturers has felt the effects of the defective batteries, including Sony, Dell, Apple, Lenovo and Toshiba.

Interestingly, Matsushita said in late 2006 that was mass producing improved lithium ion battery technology that safeguards against overheating. It is unclear if the BL-5C batteries incorporate this anti-overheating technology.

“When any supplier has a problem, it creates concern for the technology itself. The challenge that we must meet is to reassure the public that Lithium-ion batteries are safe,” said Michael Buckner, senior manager for Panasonic's Energy Solutions Lab, in an interview with DailyTech. “Safety has always been the number one priority at Panasonic. The incidents last year just reconfirmed that we need to maintain safety first in our designs.”



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RE: Ha!
By TomZ on 8/14/2007 1:41:09 PM , Rating: 2
quote:
Granted it's best to charge them till it is at a full charge then remove it. Leaving it on over night caused the issue, but the issue shouldn't have been possible in the first place.

No, the battery charger circuits for these types of batteries sense when the battery is fully charged and they automatically stop charging it. Therefore, there is no need to unplug the phone from power when it is charged.

These batteries are also supposed to have built-in temperature sensors. My guess is that the temperature sensor is failing or is otherwise not being read correctly by the charging circuit. This would result in the charger not correctly regulating the current to the battery, possibly overheating it.


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