A. Windows includes power management to automatically alert you at low and critical battery levels and to perform actions when you hit these levels. However, the default configuration is based on laptops, which have batteries that last many hours. So they typically don't do anything until the battery hits 5 percent. For a desktop or home lab server on a typical home mini-UPS, 5 percent of a charge would be around 10 seconds, not enough time to do anything useful. So it's good to change these values.

  1. Open the Power Options Control Panel applet. Click Change plan settings for your selected power plan.
  2. Select Change advanced power settings.
  3. Scroll down to Battery.
  4. Here you can change the Low and Critical battery levels for the battery. For my desktop system, I set Low to 75 and Critical to 50.
  5. Set the Critical battery action On battery: to Hibernate or Shutdown.
    Battery configuration
  6. Click OK.
  7. Click Save changes.

For my server upstairs, which draws more power and has to shut down a lot of virtual machines, I set low to 95 percent and critical to 90 percent and set the shutdown action to Shutdown (it has the Hyper-V role and can't hibernate).

You can customize the audible alerts you get through the Sound Control Panel applet. Select the Sounds tab and you'll find sounds for Critical Battery Alarm and Low Battery Alarm. By default, the sounds are generic beeping noises, but you can change them to something more urgent, like Chicken Little screaming that the sky is falling.

Low battery sound