Surface RT Battery draining faster than you're used to after upgrading to Windows 8.1? Here's a possible fix...
WinBeta - Updating Surface RT to Windows RT 8.1 results in decreased battery life, Microsoft offers fix
For those of you who own a Surface RT device and have updated to the latest Windows RT 8.1 update, you may have noticed a decrease in battery life. Microsoft is aware of this issue and has quietly issued a workaround that will fix the problem and allow you to have the full battery life potential of your Surface RT device.
According to Microsoft, the decrease in battery life when updating your Surface RT to the latest 8.1 update, the wireless adapter power policy isn't migrated for some reason. The company explains that the power policy is set to a default value that eats up your battery.
Surface RT only: Battery issue when updating from Windows RT 8.1 Preview
If you updated Surface RT from Windows RT 8.1 Preview to Windows RT 8.1, you may notice a decrease in battery life. During the update, the wireless adapter power policy isn’t migrated. Instead, the power policy is set to a default value that consumes more power both during use and in the connected standby state.
To restore the wireless adapter power policy to the correct settings, open an administrator command prompt:
Swipe in from the right edge of the screen, and then tap Search.
(If you're using a mouse, point to the lower-right corner of the screen, move the mouse pointer up, and then click Search.)
In the search box, enter command prompt.
Touch and hold (or right-click) Command Prompt to bring up the context menu. Tap or click Run as administrator.
On the User Account Control dialog box, tap or click Yes.
At the Administrator: Command Prompt, enter the following:
powercfg -setdcvalueindex SCHEME_CURRENT 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 3
powercfg -setactive scheme_current
I've heard a couple reports of friend's Surface RT batt's draining faster than they were used to with Windows 8.0. Hopefully this will fix it for them...