Hey,

I have an IBM T40. My battery lifetime is about 3 to 4 hours on windows but is hardly 1 hour under linux debian.
Do you have an idea why I don't have a better battery lifetime ?

Thanks

From Linux on Laptops IBM Pages:
http://bellet.info/laptop/t40.html
http://vernon.mauery.com/linux-laptop/
http://www.math.rutgers.edu/~amurphy/linux/IBM-T40.html
http://www.w-m-p.com/linux-on-t40.html

These are all for the T40, on the IBM page are a number of T40p specific links. They all seem to have something about power on them. Have a read and come back if anything is unclear or you need further help.

Most likely the reason is because you're not using cpu scaling on the processor. Almost all laptops use cpu scaling to reduce the voltage, hence the power the processor uses. Either get a kernel or recompile yours to enable the cpu scaling driver (should be the one for Intel Centrino I believe). I'm surprised that you said the battery time went from 4 hours to 1 because I believe Intel's mobile Centrino processor on the average uses relatively very little power (~7 watts according to intel's website) compared to AMD's (~25 watts).