The lithium ion battery is free from the so-called memory effect, a phenomenon associated with nickel cadmium in which the apparent battery capacity decreases when shallow charge and discharge cycles are repeated.
A single lithium ion cell has a voltage of 3.7V (mean value), which is equal to either three nickel cadmium or nickel-metal hydride cells connected in series. This voltage is close to the nominal VCC of the GS64 device.
Li-Ion batteries generally provide long storage life with few limiting condition, and offer problem-free charge after long storage. Under normal conditions, the lithium ion battery has a life of more than 500 charge/discharge cycles. Also, Li-Ion batteries have a slow self-discharge rate (typically 1.3% per month, compared with Ni-MH batteries which can exceed 50% per month).
Lithium ion batteries are environmentally friendly, inasmuch as they do not contain any heavy metal pollution substances such as cadmium, lead, or mercury.
There are many manufacturers of Li-Ion batteries worldwide. Sony Ericsson make no recommendations with regard to specific vendors, but here are some considerations for GS64 users which may prove to be useful in the selection process and implementation:
•Li-Ion batteries marketed for cellular (mobile) phone use may make a good choice
•battery manufacturers with heritage in supplying the cellular (mobile) phone industry could make a good choice, especially for high-volume requirements
•look carefully for batteries which are rated at temperatures that the GS64 is likely to operate at (many batteries are only specified for -20°C to +65°C operation which may not be sufficient)
•small form-factor (typically handset-sized) Li-Ion battery capacity varies considerably, some batteries are rated as high as 3200mAh (600mAh to 1800mAH are more commonly available)
•weight is generally not a problem with typical GS64 user application, even so small form-factor Li-Ion batteries (up to 1800mAh) can vary between 10 to 40 grams
•size is generally a factor of capacity, since larger capacity batteries naturally have more material/cells, and will range between 2750mm3 to 18000mm3 for small form-factor Li-Ion batteries
•the speed by which lithium-ion ages is governed by temperature and state- of-charge; high temperatures and deep discharge will effect useful life
•if possible avoid frequent full discharges because this puts additional strain on the battery, partial discharges with frequent recharges are better
•never short circuit the terminals of a Li-Ion battery
