In Ubuntu 12.04, Lenovo Ideapad S400. I finally found what worked for me. Take a look at http://askubuntu.com/questions/92794...-battery-value. It says:
Browse to org->gnome->settings-daemon->plugins->power.
Change the values of percentage-critical and percentage-action to the level you require.
And change use-time-for-policy to false
I just had to install dconf through Ubuntu Software Center to find the way. All the percentages were ok. I turned use-time-for-policy to false and restarted the session. Working fine now. Enjoy... it is always good to remove Windows from a computer.
By the way, before I intended to remove Windows (it is my 77-year-old, mother-in-law computer) after it gets 1060 viruses of 15 different kinds in the first week of use, I called Lenovo in Brazil asking them about warranty. To my surprise, I was told that Windows removal voids warranty... I must return to windows if I need that. You know what? I don't mind. Ubuntu is already installed and, except for this small battery glitch, it seems to recognize all peripherals ok.