I have a Lenovo Z470 notebook and I found the same problem when installing Ubuntu 12.04 in dual boot with Windows 7. I'm not an expert on this field but I'll describe my experience (it might help).
I have found that some Lenovo laptops, including my own and I'm not sure which other models, include an utility named Lenovo Energy Management in Windows 7 that allows users to select whether to charge to 100% to maximize runtime, or charge only partially to maximize lifespan of the battery.
Since I'm a new member I can't use images, but here is a link to an image of the Lenovo Energy Management utility.
Pertaining this utility I have noticed two things:
- In Ubuntu, in order to be able to charge the battery to 100% the Optimize for Battery Runtime must have been selected previously in Windows 7 (I don't know if this can be controlled from Ubuntu directly, perhaps an expert could help us in that issue).
- Now the bigger problem is that once you have selected the Optimize for Battery Lifespan option, even if it was only one time and you select the Optimize for Battery Runtime option again before booting Ubuntu, the Ubuntu battery indicator will indicate the battery is charging even if the power supply is not connected to the computer. So, in order to prevent this from happening you should avoid using the Lenovo Energy Management utility if you plan to use Ubuntu afterward, either clean install or dual boot.
Since most of us have already used this option at least once, I have found a workaround proposed in a thread in ubuntuforums.org proposed by member achilleas.k (not my credit). I'll cite:
Shut down the laptop.
Remove AC power.
Remove the battery.
Hold the power button for about 10 seconds.
This seemed to work for achilleas.k, some other users in that forum, and certainly is working for me. I know it's not a permanent solution, especially for those of us using both Ubuntu and Windows, but it sure helps meanwhile. Perhaps a more expert Linux user can help us out to find a formal solution using this info.
Hope it helps.