How to find out, why connected standby drains too much power

I have this issue on a lot of my tablets, my friends have this issue too, so I don't know, why it's so hard to address this problem and why MS doesn't do anything about it. It was already a problem with Windows 8.

It's really easy, to "mess things up", so that Windows wont properly work on a tablet and will drain too much energy in connected standby. That still shows so easily, that Windows is still a desktop OS, and not optimized for handheld devices.

I know, that there are three "hidden" tools coming with Windows:

powercfg /energy
powercfg /batteryreport
powercfg /sleepstudy

But looking on those, I don't see anything suspicious or "wrong". I know the fact, that the normal drain should be around 0.33 to 0.5% / hour on tablets, that's the margin for InstantGo/Connected Standby MS declares. But mostly all my devices drain about 1-2% per hour in connected standby.

I have nothing running on those devices, deactivated OneDrive (which isn't working too btw correctly and is still bugged under Windows 10, and if it's on, the drain is even worse).

I have disallowed the speaker/sound chip to wake up the device from standby, this a bug since Windows 8 and not fixed by MS.

One of my tablets has dual-boot and Android is running next to WIndows, and the drain under Android is normal/great compared to Windows.

I would welcome any help to find out whats causing the drain, thank you very much.

What do you mean under "standby"?
You should look into the list of programs allowed to run under lockscreen, this is my first and main guess.
Track My Device can also drain power as well as active and full backup.
PS: I don't have a tablet, these things are based on my experience from Windows 10 Mobile.

I know that in Settings there is a Battery Saver option which shows Battery Use of various apps, although I'm not sure if it's still measuring in Connected Standby mode.
And I'm not sure how much it adds to the powercfg reports.
Some devices have Power Management options in Device Manager which say 'allow windows to turn off this device to save power' but I'm not sure how effective that is, and in my experience can cause problems on some hardware on waking from Hibernate/sleep.

OK I see I'm a bit late with this information... but just in case someone else sees this thread I did come across something which might help diagnose Connected Standby issues.
From this MSDN page:

Starting with Windows 8.1, a software tool, SleepStudy, became available as an inbox component in all Windows PCs that implement the modern standby power model. SleepStudy can measure modern standby performance with minimal impact.
...
To run SleepStudy, open a Command Prompt window as Administrator and enter the following command:

Code:

powercfg.exe /SleepStudy

But given the OP tried Sleepstudy and it didn't work... from this one:

The Windows Performance Analyzer (WPA) lets you view traces of system activity displayed in a graphical format. WPA is used for many Windows performance and debugging scenarios, and is the second-level triage tool for modern standby issues that cannot be resolved by using SleepStudy.