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 GR64 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 GR64 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 GR64 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
•do not expose Li-Ion batteries to moisture or rain
•monitor battery temperature during charging using a thermistor placed on or near the battery wired to an ADC input on the module
•Li-Ion batteries have a higher ESR (compared to Ni-Cd or Ni-MH), although this should not be a limiting factor for peak current delivery, any battery should be capable of at least 50% greater than the GR64 demands (~3A pk)
