my battery last me over 36hours with one single charge.

Wifi on and off very often. Sometimes checking the web for more than 1hour each time.
Taking snapshots and videos,
Customs apps installed.
Plenty of short cuts on screens.
Web browsing, email checking.
Playing Music and Videos casually.
SMS none stop, and answer a few phone calls (20mins).
3G connection always (set to Dual).
Playing some games (Chest, Blocks), and third party games (SNES..etc)
Screen Brightness set to 2 bars.
Sending photos to other phones through bluetooth.

All that last me over 36hours.

So far it is doing pretty well. I notice that my idle time is very long. I left it 12hours IDLE but I did not see any fluctuating in battery power at all. Charged it and left it over 12hours and it only used 5-7% of juice.
With my calculation I think it would last me 170-240Hours if I leave it on Idle all day without using it.

But I already bought another Genuine BL-5J battery in case of emergency when i'm away from home or recording videos constantly