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 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 I 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?