I bought my galaxy mini last week and since then I've learned alot about battery life and other stuffs, first of all the phone don't show anything when it's fully charged (really fully charged), It'll often say it's already 100% when charged about (for my phone) 2 and a half hours but when it's unplugged the battery will drop after a while to 85-95%. So the best thing to do is to extend charging time from 30mins to 1hr when the phone says it's on 100%.
To extend battery life i suggest to have juice defender, It extended my battery life by 14% (juice defender's approximation). I turned off my 3g, BT, GPS, WiFi and I only turn them on when I need to use 'em. I lowered my screen brightness, and sometimes closing background apps that I don't use. I also rooted my phone and used SetCPU, now i ranged my phone's frequency from 122-600MHz so that when less apps is running, my phone will run with low frequency. I also set a profile to use only 122MHz when on standby mode.
When the phone only uses 122MHz, battery usage is dropped to 20.3% (computed using (V^2)f )
Overall:
I charge my phone 3 and a half hours.
Average usage: 35hrs.
Minimum Usage: 3 days (approximate).
Constant Usage: 17hrs.
Heavy Usage 10hrs.
To extend battery life i suggest to have juice defender, It extended my battery life by 14% (juice defender's approximation). I turned off my 3g, BT, GPS, WiFi and I only turn them on when I need to use 'em. I lowered my screen brightness, and sometimes closing background apps that I don't use. I also rooted my phone and used SetCPU, now i ranged my phone's frequency from 122-600MHz so that when less apps is running, my phone will run with low frequency. I also set a profile to use only 122MHz when on standby mode.
When the phone only uses 122MHz, battery usage is dropped to 20.3% (computed using (V^2)f )
Overall:
I charge my phone 3 and a half hours.
Average usage: 35hrs.
Minimum Usage: 3 days (approximate).
Constant Usage: 17hrs.
Heavy Usage 10hrs.
Just charge it overnight. It works for me. Even if you use it often in a day or play your apps for hours.