I have recently come across Zeam Launcher. After trying out the most popular ones - Launcher Pro and ADW - I thought it would be just another minor launcher and a waste of time. A waste of time considering that both launchers I tried earlier happened to be battery vampires and the phone's lifetime on a single charge was significantly reduced, compared to when I was using stock TwLauncher that came with Galaxy S.
With TwLauncher and carefully selected widgets and services, enabling radio only when needed, I could make full 7 days of battery life on a single charge. This was the maximum period so far, with normal phone usage, including phone calls, SMS, taking photos, uploading to Facebook, checking train schedule online, etc.
Another interesting thing to add is that some widgets appeared to draw battery power so I tended not to use them. One of these was excellent CalenGoo monthly widget. It presents a nice monthly view of calendar events and tasks on one screen. Very convenient and provides easy overview of almost everything I plan to do during the month. However, because of lowering the battery life, I did not use that widget and had to live with others that did half the job.
Now, the "experiment" happened in a standard way: I disabled all the radio on the phone. Zeam was set as the default launcher. Just for the fun of it, I also added CalenGoo monthly widget to it in order to test the combination of both of these components. After being fully charged, the phone wakes me up sometimes in the middle of the night with a bleep that indicates that it wants me to disconnect it from the power source. I do that and, after five hours, I wake up, turn the phone on and continue using it in my standard fashion during the day. The surprising thing was that when I turned the phone radio on, the battery was still at 100%. This was a pretty good indicator considering that bad components (widgets, launchers, services...) used to drain heaps of power even though I never touched the phone during that period. The worst ever was Launcher Pro that suprised me, first thing in the morning, with battery being at around 70% only a few hours after being fully charged and not used in the meantime! So, battery being at 100% with Zeam, and even having CalenGoo widget (that used around 15% when it was running on TwLauncher, in identical scenario) was a great sign.
After using the phone normally - only a few photos taken, sms sent/received, and phone on during the day the battery was at 95% after 17 hours! At this point I am turning the phone off (cause I like not being woken up by phone calls on weekend) so I assume battery usage will, pretty much, remain where it is. Even if it drops a notch or two, it will still be less than half of what TwLauncher uses. All other widgets are still there so this means I even have an extra widget now. And not just any widget - I got my ultimate calendar widget that displays both events and tasks in a monthly grid view.
Now I wonder how long the battery will last with the new launcher. If the record was 7 days so far, and currently the phone uses less than half of what it used to, should I, then, hope to make it to two weeks?! :)
I will update the post with the info during this week (or maybe next, if the battery goes for longer :).
If you're looking for more tips on how to improve Android phone's battery life (I use Galaxy S), read my Battery Tips for Android.
UPDATE: After two days of light phone use, the battery drain was steady at around 6% per day for light usage! I love this little piece of software (Zeam). Totally recommended if you want to spend your battery charge on meaningful things instead. :)