Update: 9th full discharge on my Sun Global 1800mAh battery.
Wed 1pm full charge
Fri 4pm - left 1 bar. 8pm low battery warning.
Fri 11pm full discharge
9th discharge = 58 hours (normal use)
8th discharge = 65 hours (minimum use)
7th discharge = 46 hours (normal use, with extra 30 sms)
6th discharge = 52 hours (normal use)
5th discharge = 62 hours (normal usage, but final 1 bar test to maximum ~6 hours)
4th discharge = 68 hours (note: even less usage than 3rd discharge)
3rd discharge = 51 hours (note: less usage than previous)
2nd discharge = 44 hours only
1st discharge = 51 hours
Comment: For new battery, the low-battery can last longer. With very low usage, seems like the battery can reach 60 hours. Need to monitor further.
Note: 99% on GSM (not UMTS)