My W520 wakes from sleep by itself. When I run the Start>Sleep function in Windows and wait until the LED around the power button is fading in and out. Then a few hours later it's apparently awakened from Sleep mode (even with the lid closed) and my battery is drained all the way to 0%.
What could be the cause of this?
There are several possible reasons why your system 'wakes up' from Sleep mode by itself.
External devices connected to your system could be a cause; as would connection to a wired network.
To check what is causing your system to wake, go to a Command Prompt and type in
powercfg -devicequery wake_armed
A list of devices that are currently configured / enabled to wake the system will be returned. For example, when run on a ThinkPad with wake on lan ethernet capability, this results:
To deactivate the devices that cause this, go to Device Manager and find the device.
1) Right click on the device
2) select properties
3) select power managment tab
4) uncheck the box that says "allow the device to wake the computer"