Ultra-Thin

[GuruAid-CS]

Following the steps below may resolve the issue:
1. Shut Down your laptop, then plug-off the power adapter, and then remove the battery from your laptop.
2. Now, keep the Power button on your laptop gently pressed for around 40 seconds.
3. Reconnect the power adapter without inserting the battery.
4. Power On the laptop.
5. Once you are into Windows, Shut it down again.
6. Now, remove the power adapter, then reseat the battery, then reconnect the power adapter, and then reboot again.

If the issue still persists, you may consider recalibrating the battery. To know more about this, the following links can be useful:
http://acer.custhelp.com/app/answers/detail/a_id/11574/~/how-do-i-calibrate-my-battery%3F
http://acer.custhelp.com/app/answers/detail/a_id/2430/related/1
If the issue still persists, there may be some issue with your battery. It is recommended to try using a spare battery (if possible) or contact nearest Acer Service Center for further assistance. This link can be useful:
http://us.acer.com/ac/en/US/content/service-contact

[venkat_ns]

Mine is an in-built battery. cannot seperate it. really worried about this, I bought this just three months back

[GuruAid-CS]

As the battery is in-built and your laptop is under warranty, it is recommended to visit the nearest Acer service center at the earliest to get the issue resolved.