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Note: Tips on the usage of the Li-ion battery of the notebook PCs
:

According to the recent knowledge on Li-ion batteries, a constant recharge scheme will hurt the battery and bring it to
a premature degradation. If you use a notebook PC manufactured prior to summer 2007, it is likely that it does not
incorporate the preventive scheme for the degradation of the Li-ion battery, resulting in an incident such that the voltage
of the battery shows 0V when you want to use it outdoors with the battery. For instance, the battery of a small mobile PC
purchased 1.2yrs ago showed 0V just after half-year use. Whereas, a newer mobile PC purchased last summer 2007 has
a preventive software incorporated. --- I usually build desktop PCs for myself, but I cannot make tiny notebook PCs. (^^)/"

When a notebook PC is connected with AC adaptor, a frequent recharge occurs every time it detects the decline of the
voltage; since any Li-ion battery tends to self-discharge in the course of time, it comes to be recharged in a periodical way.
(Such a decline occurs even in NiMH rechargeable batteries ---except for ENELOOP or Cyber NiMH batteries, which are
slated to keep about 90% even after a few years on the shelf.) If you want to avoid such a premature degradation and
inconvenience, (since a typical Li-ion battery for notebook PCs costs around $250. )
1. remove the battery when you use PC with AC adaptor on the desktop, and recharge it up to about 80% capacity
when you carry it with you outdoors.
Or,
2. Use it only with battery and recharge it with AC adaptor when needed. Download a new driver for a wiser management
of the Li-ion battery if the manufacturer provides such a new driver. I prefer Method 1 at present.

In addition, almost all Li-ion batteries manufactured prior to summer 2007 use Li-Ni electrodes, which are vulnerable to the
heat produced through the usage of PC. Try to cool the PC with Alumium block, for example. You might recall the world-
wide erecallf made by Sony. Newer Li-ion batteries use Li-Mn electrodes, which have higher resistance to heat. Some
manufacturers, such as Toshiba, Hitachi, have recently produced newer, high-capacity Li-ion batteries that are also heat-
resistant. They may be used in the next generation electric cars in the near future.

As of Apr. 2011, Sony began shipping the battery pack made of LiFePO4, which shows much better resistance for degradation.
A newer generation of Li-ion battery named 'Nexelion' holds fairly higher capacity than the previous ones.

In a following battery pack, shown in Fig. 1, two Li-ion cells, 3.7V, 2600mAh, are connected to supply 3.7 x2 = 7.4V.

Sample pic Li-ion 18650 cells

Fig. 1 This Li-ion Battery Pack uses two cylindrical 18650 Li-ion cells.
(18650 = 18mm in diameter, 65mm in length)

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