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Thursday, February 05, 2004
Ng: Exploding batteries in cell phones
By Wilson Ng
WIRED DESKTOP
HORROR STORIES. During the past several months, you may have read horror stories about exploding batteries in laptops and cell phones. any of these stories came out in reputable news sources. A search in Google for exploding cell phone batteries yielded over 20,000 links, which means this could be a growing problem.
I decided to do some research (through the Internet, of course). I hope this is interesting as there are probably over 20 million cell phones now in the Philippines, and way more batteries.
Most of the batteries in notebooks and cell phones are of the lithium-ion type. They replaced the nickel metal hydride of yesteryears.
There are several advantages—these batteries usually pack more energy, are lighter, and eliminate the memory effect (Before, it was advised to fully drain the battery before charging it to retain its life, but now this is less of an issue with lithium ion batteries).
However, many lithium ion batteries use a chemical called cobalt oxide, which can undergo a “thermal runaway” heat up.
That means when this material heats up to a certain temperature, it can self-heat and progress very fast into a possible fire or explosion.
This still happens very rarely, lest people panic. But it is probable these occurrences will increase.
Battery problems that can result in fires or explosions may be caused by short circuit, excessive heat, overcharging or abuse. Therefore:
l It is advisable that lithium ion batteries be used for no more than two years.
l Notebooks or cell phones should not be left in cars or places where the temperature may go over 60 degrees centigrade.
l Don’t place cell phones or batteries in pockets or drawers together with coins or keys. The metals might come in contact with the battery or cell phone terminals, and cause a short circuit.
l Batteries should be disposed of properly.
Early last month, the US Consumer Product Safety Commission mandated the replacement of batteries in Kyocera model 7135 cell phones sold in the Northwest United States.
On four occasions, the batteries were said to have short circuited and triggered a built-in mechanism to release the superheated gases. On one occasion, a man suffered burns on his leg when the heated gases were released in his pocket.
Other batteries (supposedly fake Nokia batteries) did not have the proper circuitry to shut down the power source when it began overheating, and thus exploded. When heated gases cannot be released, they can melt the phone’s plastic casing, and circuits.
This affects most phone manufacturers, who agreed that this has been happening with increasing frequency.
Two months ago, Nokia documented three incidents of exploding handsets—two in the Netherlands, and one in Vietnam, and blamed counterfeit batteries manufactured by unauthorized suppliers.
Counterfeit batteries are generally cheaper, and some almost indistinguishable from the real ones.
Last year, over five million counterfeit batteries were seized, proving that fakes by the tens of millions are probably being sold every year.
(e-mail: wilson@ esprint.com.)
(February 5, 2004 issue)
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