I've got about a 3 or 4 hour battery life on my laptop. I've had Ubuntu 11.04 on it for a week or so now, and yesterday, it started telling my I had a critically low battery (.3%), and suspends. When I plug it in and unplug it a few times, it stops complaining, and runs for hours. Is there a way I could fix this, or even just tell Ubuntu to ignore a critically low battery?
I suggest trying to let your laptop battery drain all the way (you might need to turn off the auto-suspend) and then letting it charge all the way up, all while running Ubuntu. It's often hard to know a battery's "empty" and "full" states without having some kind of measurement, and if this calibration is way off, then the percentage will be way off as well.