More News from the Sony Battery Front
Sony has had a lot of recent problems with batteries that they have manufactured for use in laptop computer. The latest word is that they will conduct their own replacement program.
They have said that they are planning a worldwide program to replace batteries that use certain Lithium-Ion cells. Sony says that microscopic particles in the batteries can come into contact with other parts of the cell to cause a short circuit. They go on to say that the batteries will normally power off at this point, but under some conditions the short circuit may cause the batteries to overheat and catch fire.
So far four notebook vendors have recalled some Sony batteries. Dell was the first when they announce a recall of 4.1 million batteries. They have since increased the recall to 4.2 million. Apple followed with a recall of 1.8 million batteries. Toshiba had offered an exchange of 340,000 Sony batteries, not due to fire hazard, but a report that the batteries could be defective and unexpectingly cut power to the notebooks. The day before Sony’s announcement Lenovo became the 4th vendor to recall Sony batteries in 526,000 ThinkPads.
It’s possible that other laptop manufacturers using Song batteries may join the recall program.
Lithium batteries actually started back in 1912 but never became commercially available until after 1970. Rechargeable Lithium batteries were made in the 1980’s, but failed due to safety reasons. Research since has uncovered inherent dangers in the design of a lithium metal electrode battery and focus has shifted to using non-metal electrodes and lithium ions. These batteries have less energy density than the full metal electrode variety, but are inherently a lot safer, and have found their way to being one of the most popular battery chemistries currently.
Below is a good excerpt from an article entitled “Taking the Mystery out of Battery Charging” from the July 2004 Issue of “What’s New In Electronics”
Lithium Ion cells (as opposed to battery packs) are so sensitive to charge and discharge conditions they require special electronics built into the battery as protection.
Lithium Ion cells do not tolerate overcharge hence charging must be terminated when the battery reaches full charge.
Lithium Ion cells do not tolerate over-discharge and cells must not be discharged below 2.5 V/cell or permanent damage may occur.
Lithium Ion cells are charged at 4.1 or 4.2 V/cell with a maximum current of C/2.
Batteries should be charged after use as self-discharge can discharge the cells below 2.5 V and cause permanent damage. Lithium Ion batteries do not suffer memory effect and like Sealed Lead Acid (SLA) batteries give longer life from shallow discharges.
Lithium-Ion batteries do not suffer from the same memory effect as do NiCd batteries and they have a much higher energy density. They do suffer from over charge, over-discharge, and self-discharge.
Additionally Lithium-Ion batteries have a useful life of 3 years from day of manufacture. Battery temperature above 40C or 104F can lead to reduced capacity. They will lose about 10% of their charge per month.
It’s possible to use Lithium-Ion batteries without any dangers, but they need to be used property. The electronics involved should prevent accidents from happening, but users need to not allow the batteries to discharge below about 30% capacity on a daily basis, otherwise battery capacity can be affected. This is one battery that shallow discharges may actually be better for the life of the battery.
© 2006 Steven G. Atkinson – All rights reserved – tt4sb.com
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