I've Lenovo S400 laptop, dual boot with windows 7 and ubuntu 13.04. The problem is that whenever I disconnect the power adapter, ubuntu shows that that battery level is critically low and goes to sleep. When I resume it from sleep, it runs fine on battery power. The problem might be the lenovo power management installed in Windows. When I set it to battery health mode, the battery doesn't charge over 60% and is good for battery health if you use the laptop mostly connected to power, and that's when it causes the sleep problem. When it is set to battery full charge mode, ubuntu just shows a warning of low battery for a moment but then runs fine. In either case, the battery meter never works (shows 1% battery charge) while connected to power.
It looks like ubuntu takes a couple of seconds to detect the correct battery level and that's creating all the problem. Lenovo doesn't provide any driver for ubuntu. A faulty battery meter (only when connected) is not an issue but the sleep problem is a bummer. What can I do?