The TW100 uses Microsoft Windows 8 new Instant-On or Connected Standby to stay connected to the internet. This new SoC compatible standby mode uses a lot more energy than the standby on other tablet. Note: This tablet has no applications installed.
powercfg sleepstudyThis chart shows the continual power drain on this tablet across the weekend.
The table after the chart shows that we were in the low power state 99% of the time.
powercfg creates a chart that shows the activity intervals on the tablet. Windows 8 tablets wake up every 32 seconds. Values other than 32 seconds mean some program is causing activity and using power. This chart shows that my tablet has no other activity.
The offender section shows which hardware causes the activity. The machine is 99% idle. We can see here that the I2C controller and SD card account for the < 1.5% active time.
powercfg also shows the programs that cause the activity. It finds no programs as the cause of my battery usage on this TW100 Windows 8 tablet. This means all of this activity is related to the core functions of the Windows operating system, the SoC and this standby mode.
Windows 8.1 InstantOn (formerly InstantGo) provides a high level of connectivity for windows tablets when they are idle. This is great when you are actually using your tablet or have it plugged in continually. InstantOn can completely eat the battery when the tablet is not actually in use, draining a full battery within a couple days.
The only way to guarantee a working tablet on Monday morning is to either leave it plugged in or power the machine off on Friday. The TW100 cold boots in 5 seconds so a full powerdown isn't that big a deal.