QUOTE(OrCaGaL @ Jun 19 2009, 08:02 PM)

a total PRO...thanks a lot for the help! hope my mp3 walkman is able to sustain me for 30++ hours after those 3 FULL charge...

I in doubt you can go for 30++ hours with current Malaysia temperature. Let me enlighten you with battery knowledge, facts and reality...
Lithium-ion works within the discharge temperature limits of -20°C to 60°C (-4°F to 140°F). The performance is temperature based, meaning that the rate capability at or below -20°C is reduced due to the increased impedance of the electrolyte. Discharging at low temperatures does not harm the battery. Lithium-ion may be used down to -30°C (-22°F) with acceptable results. Larger packs will be necessary to compensate for the reduced capacity at these temperatures.
It is not recommended to discharge lithium-ion at temperatures above 60°C. A high discharge rates combined with elevated temperatures can cause self-heating, an effect that could permanently damage the separator and electrodes of the cells.
The recommended storage temperature for most batteries is 15°C. Let's go to my point now....
Facts:
Sony test the battery with player in lab which is have a temperature really cold. I would say 16°C.
Sony test playing using the lowest bit rate acceptable by our ears.
Sony disable all the setting like equalizer.
Sony test with LCD off.
Reality:
Our temperature now 35°C+. The higher the temperature, the fastest battery discharge.
We using higher bit rate song like 192kpbs and can be up to 320kps. The higher the bit rate, the bigger the file and need more battery power to access and to process the song.
We use equalizer to suite our liking. That use more power.
We keep changing the song and that will make the LCD switch ON. Well more power again.
There is more actually but that should be enough to make it understandable.
That why if you read the manual, there is a clause say, battery life is depend on.... bla...bla... (check yourself).