I have HP ProBook 4530s. In Windows 7 after installing all HP drivers the 6-Cell battery works perfectly for 2+ hours but in Ubuntu 11.10 and now in 12.04 the battery time is not sufficient. It works hardly for 1 or 1.5 hours only. I have installed ATI's Linux Driver for the RADEON card.
I have noticed that in Windows only 4 processor core are active most of the time and remaining are put in off-line mode until required. However in Ubuntu all 8 processors cores remain active.
Powertop shows a battery discharge of 25 W up to 28 W.
How can I tune-up the power management especially make unnecessary active processor off-line?
I've suggested this before in other posts cpu indicator --- http://www.ubuntugeek.com/indicator-cpufreq-cpu-frequency-indicator-ppa-installation-instructions-included.html --- I use this. I had similar issue with only getting two hours, but this extended it an hour on 11.10. Then with 12.04 jumped to 5 hrs. I think it works great but for some it doesn't work.
ALSO
This is a powertop link --- http://tombuntu.com/index.php/2008/09/09/reduce-power-usage-with-powertop/ --- you can stop different softwares from waking up you computer's cpu, when it is idling. forget the italicized.