I was using my Acer laptop this morning and this warning just popped out.

Some useful information was found here: http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/consider-replacing-your-battery-issue-in-windows-7/b2ffdaa5-e62f-47dd-9336-da268e0f54ed

1st of all, run the command prompt with administrator privileges and in command prompt, change the destination path to C:\ and then type POWERCFG -ENERGY. It will scan ur battery status and after 1 minute, it will generate a report which will be saved in the same destination in which the command had been performedi.e C:\. Open the energy report and check the battery's designed capacity and the last full charge. There will be a difference in both values as well as in the red columns (which are the warnings)it will be saying that battery has been charged below 40%. Note the last full charge reading and then perform the below given steps...this was mine figures: -

Battery:Battery Information

Battery ID	SANYO GC86508SAT0
Manufacturer	SANYO
Serial Number
Chemistry	Lion
Long Term	1
Design Capacity	44400
Last Full Charge	30470  (it was at 11780, now see the difference by yourself)

charge the battery completely, after that, start using laptop on battery and unplug the charger. Use the laptop until it automatically shut down itself. When it gets shutdown, On it again without plugging the charger and start using the laptop until and unless the battery is totally emptied. Then plug in the charger and  start charging battery, again perform the same steps, after that,  run the POWERCFG -ENERGY and check the last full charge reading. Perform these steps until ur last full charge crosses the 40% of the design capacity. still facing problem, then contact me on*** Email address is removed for privacy ***, cell # +(removed).