Number 283 - December 2006

Battery Recalls
by Gerry Ching. Santa Barbara PCUG, September 2006
The recal of 4.1 million Li-ion laptop batteries by Dell and the smaller recall by Apple were triggered by overheating and fires in a few laptops. These incidents were apparently caused by defective cells manufactured by Sony, a major supplier of laptop batteries.    Fujitsu and other Japanese computer makers said on Thursday that no recall of batteries made by Sony was necessary as their computers were designed to avoid overheating. A Fujitsu spokesman was quoted as saying "Most Japanese makers don't allow high voltage to flow from their AC adapters to the computer battery, out of safety concerns."    Hogwash!    I'd take this claim with a grain of salt. Dell typically uses 20 volt battery packs and charging voltages can easily approach 30 volts, but this is hardly considered high voltage. Fujitsu, Toshiba and Hewlett-Packard use Sony lithium-ion battery packs but the batteries used are different from those shipped to Dell. That is a more reasonable explanation.    In addition, a number of battery incidents occurred when the laptop was turned off and not being charged More    Recently, Panasonic has joined the battery recall club. They deny that Sony-made batteries are involved. Instead they say that this particular issue involves the possibility that a small piece of a metal spring could break off [in] a battery or notebook that was dropped or impacted. Ideal Battery?    Li-ion batteries are commonly used in laptops as they have the highest energy storage density	per weight of any commonly-used battery. These require 'smart' chargers that switch off when they sense that the battery is fully charged. All laptops have these 'smart' chargers.    The large energy storage of these batteries is necessary to power the modern laptop, but can be a problem if the battery malfunctions. The typical laptop battery stores enough energy to keep a 50 watt ligblbulb lighted for an hour.    Most Li-ion batteries have internal fuses, to protect them against external shorting of their terminaIs, but is of no use if the battery shorts internally.    Recommendations    Very few documented incidents of battery overheating have been reported The user should be aware that defective parts creep into the manufacturing cycle, especially with the dramatic reduction in cost of the mainstream laptop.    You should probably keep an eye on a charging laptop. This should not be a problem as most will reach full charge in several hours.    Also be cautious of using after-market replacement batteries. these are available for sometimes half the cost of a cerlified replacement. But there may have been poor quality controls during the manufacture of these batteries. A common ommission, even in cell phone batteries, was the lack of internal fusing.    Also be aware that most Li-ion batteries will deteriorate as a function of age, even if they are not used. Check the manufacturing date and send it back if it is over a year old.
Number 283 - December 2006