From time to time batteries on laptops wear out and lose their calibration settings in Windows. Its a relatively simple task to get windows to recalibrate the battery or 'relearn' the settings again, so please follow this battery calibration guide.
Please completely power the laptop off and remove the power cable and battery
Connect just the power cable, leave the battery disconnected and power the laptop on
Once Windows 7 loads, click on start and then on control panel. Once the control panel menu loads we need to select system. Once the system menu loads we then select Device Manager on the upper left hand side of the menu so that we can see the devices installed in the laptop.
Double click on batteries to expand the battery device section and you should see 3 or 4 devices. We need to uninstall the Microsoft ACPI-Compliant Control Method Battery. If there are 2 of them we need to uninstall both of these. So to uninstall this device we simply right click on it and select uninstall.
Shut the laptop down and remove the power cable
Connect the battery first to the laptop and then reconnect the power cable and turn the laptop on
Once windows loads it will reinstall the Microsoft ACPI Battery control settings and start to charge the battery.