[HDoaLC] Power Management

One of the biggest challenges I have hit with using a Hyper-V virtual machine on my laptop as my desktop environment has been power management.  I was expecting this, as Hyper-V has been designed for servers and not for laptops.

The first issue I have encountered is battery life.  When running Windows 7 natively on my laptop – I can get about 2.5 hours on my battery.  When running Windows Server 2008 R2 + Hyper-V + Windows 7 in a virtual machine I can get about 1 hour and 10 minutes.


For the most part I have taken to carrying my power supply around with me (thankfully most Microsoft conference rooms have ample power outlets).

The next issue is related to the first.  Normally when Windows runs low on power it puts your laptop to sleep.  Unfortunately Hyper-V disables the ability to sleep.  As such I had to make some changes to the default power policy.  The first change was to configure Windows to shutdown when power got low instead of sleeping.  The second change was to raise the critical power warning from 7% to 12% – as my laptop needs to have enough time to shut down correctly.

One last issue that I have yet to find a solution for is the fact that when I am running the laptop in full screen mode, I do not get to see what the battery charge level is on my laptop – which means that it is always a surprise when the system shuts down from low power.  I have poked around and found that there are WMI interfaces that I could query over the network from the virtual machine that would allow me to see this information – but I have not had the time to actually try and put something together here.