I've done a clean install of Windows 7 x64 on an ASUS X501A laptop. The battery is detected and shows in the system tray as "plugged in, charging". However the charge level stays at 76% and if the AC cord is plugged out the laptop turns off. The laptop does not turn on without being plugged in either. Everything worked perfectly prior to reinstall.

I've tried:

• Downloading and installing all the ASUS drivers, including the ATK ACPI driver
• Checking the BIOS - there do not seem to be any battery-related settings
• Flashing the BIOS to the latest version
• Uninstalling Microsoft ACPI-Compliant Control Method Battery in device manager as suggested on the internet
• Full power discharge/ATX reset as suggested by ASUS support: remove mains power charger, remove battery, press and hold power button for 10 seconds, reconnect battery and mains and turn on

I have a feeling all this may have something to do with the EFI BIOS that comes on the laptop. During the reinstall I had to delete all partitions and start anew, because the Windows installer complained about the improper order of GPT partitions. The EFI System Partition was recreated by the installer, and I am guessing that it may be missing the particular ACPI driver needed to make the battery work.

I've tried researching this, but could not come up with any useful info. I am hoping someone here may know a bit more about this and maybe help me understand what's going on and how to fix it. Barring that, I'll have to re-image the drive off an identical ASUS laptop with stock install and hope it fixes things.