For those of you out there who happened to own a Surface RT tablet and have already installed the preview version of Windows 8.1, then you might be one of those who have been affected by some bugs. Apparently, one niggling issue involves a rather serious battery drain on the tablet, and a rather unorthodox workaround has been solved by the folks over at Microsoft.
A thread at the Microsoft Support forums claimed that a Surface RT owner happened to be experiencing a battery drain at a rate of between 2% to 3% in just an hour when it is in Connected Standby mode with the preview version of Windows 8.1 installed. He decided to post that a driver which is known as Microsoft UART V2 Driver (\_SB.UAR3), as that seemed to be the main culprit where draining the battery is concerned as he used the Powercfg /sleepstudy command.
A Microsoft support member responded that the solution was to turn on the Bluetooth’s connection on – which does sound rather counterproductive at first, since wouldn’t that use more battery power? Apparently, the affected user must have been at his wits’ end to give it a go, and voila! The battery drain issue was fixed. An explanation by the Microsoft support team member can be found after the jump.
Powercfg /sleepstudy reports any issues that are preventing the CPU from entering its lowest power state during Connected Standby (e.g. screen is off). In this case, the state of the specific UART controller is preventing the CPU entering its lowest power state. This UART happens to be connected to the Bluetooth radio on Surface. Unfortunately, the bug that causes this bad state occurs exactly when the Bluetooth radio is turned off in PC Settings.
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