Windows 8 tablet (battery) dies in 2 days because of Instant-On

I have a Windows 8 / 8.1 TW100 10" quad core tablet that leave at work as an inexpensive internet device.  The device is always dead with 0% battery when I arrive at work Monday morning. The thing has good battery life when I'm actively using it.  I have to charge the device and reset the clock every Monday. (The clock is dead because it relies on the main battery as the clock battery).  My IPad 2, by comparison, sits standby for days/weeks without draining the battery.

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.


You can use the "powercfg" command to analyze battery usage. It generates a nifty HTML file that describes battery usage across the last 3 days.
powercfg sleepstudy
 This 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.

Conclusion

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.

Comment

I don't need for my tablet to communicate continually with the network when I'm not using it.  I wish Microsoft provided a way of adding additional power plans to tablets. They currently limit you to the InstantOn if it is installed by the OEM.

Comments

Post a Comment

Popular posts from this blog

Installing the RNDIS driver on Windows 11 to use USB Raspberry Pi as network attached

Image
I do a lot of my development and configuration via ssh into my Raspberry Pi Zero over the RNDIS connection. Some models of the Raspberry PIs can be configured with  gadget drivers  that let the Raspberry pi emulate different devices when plugged into computers via USB. My favorite gadget  is the network profile that makes a Raspberry Pi look like an RNDIS-attached network device.  All types of network services travel over an RNDIS device without knowing it is a USB hardware connection. A Raspberry Pi shows up as a Remote NDIS (RNDIS) device when you plug the Pi into a PC or Mac via a USB cable. The gadget  in the Windows Device Manager picture shows this RNDIS Gadget connectivity between a Windows machine and a Raspberry Pi. The Problem Windows 11 and Windows 10 no longer auto-installs the RNDIS driver that makes magic happen. Windows recognizes that the Raspberry Pi is some type of generic USB COM device. Manually running W indows Update  or  Upd...
Read more

Understanding your WSL2 RAM and swap - Changing the default 50%-25%

Image
The Windows Subsystem for Linux operates as a virtual machine that can dynamically grow the amount of RAM to a maximum set at startup time.  Microsoft sets a default maximum RAM available to 50% of the physical memory and a swap-space that is 1/4 of the maximum WSL RAM.  You can scale those numbers up or down to allocate more or less RAM to the Linux instance. The first drawing shows the default WSL memory and swap space sizing. The images below show a developer machine that is running a dev environment in WSL2 and Docker Desktop.  Docker Desktop has two of its own WSL modules that need to be accounted for.  You can see that the memory would actually be oversubscribed, 3 x 50% if every VM used its maximum memory.  The actual amount of memory used is significantly smaller allowing every piece to fit. Click to Enlarge The second drawing shows the memory allocation on my 64GB laptop. WSL Linux defaul...
Read more

Almost PaaS Document Parsing with Tika and AWS Elastic Beanstalk

Image
The Apache Tika project provides a  library capable of parsing and extracting data and meta data from over 1000 file types.  Tika is available as a single jar file that can be included inside applications or as a deployable jar file that runs Tika as a standalone service. This blog describes deploying the Tika jar as an auto-scale service in Amazon AWS Elastic Beanstalk.  I selected Elastic Beanstalk because it supports jar based deployments without any real Infrastructure configuration. Elastic Beanstalk auto-scale should take care of scaling up and down for for the number of requests you get. Tika parses documents and extracts their text completely in memory. Tika was deployed for this blog using EC2 t2.micro instances available in the AWS free tier. t2.micro VMs are 1GB which means that you are restricted in document complexity and size. You would size your instances appropriately for your largest documents.   Preconditions An AWS account. AWS ac...
Read more