Is There Phantom Power Usage In Your Home?

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Dr. David Schmidt of the University of Minnesota’s College of Food, Agricultural and Natural Resource Sciences is practicing what he preaches. The professor of the popular Renewable Energy and the Environment course has conducted his own study on phantom power in the home.

Phantom power (also referred to as standby power, vampire draw, or leaking electricity) is the act of electrical appliances consuming power while switched off or in standby mode. Schmidt ran an in-home experiment with a Kilo-Watt meter and tested items such as laptops and phone chargers.

Schmidt began the experiment by plugging only the power cords (chargers) for 4 laptops, 2 cell phones, 2 iPads, a Nook, a Nexus, and an iPod all onto the same power strip. (See above right photo). Even with all of these chargers plugged in, the meter read 0 Watts.

Next, Schmidt connected all the devices to their chargers, made sure all devices were on, fully awake, and charging. At this time in the experiment the Kilo-Watt meter read above 195 Watts.



Continuing the experiment, Schmidt then put all the devices into their sleep mode, but maintained that they were all still charging. This reading level was roughly 150 Watts.



Lastly, Schmidt took a reading of the devices when they were all connected to their chargers, in sleep mode, and fully charged. This reading was 8 Watts.



Schmidt concluded that:

  • Most of the chargers alone likely used a slight bit of power; however, all combined it was still less than 1 Watt—the impact of leaving chargers plugged in is negligible.
  • Having devices plugged in after they have been fully charged will result in phantom power use and should be avoided.

It’s hands-on projects like the one Schmidt conducted himself that he encourages students to undertake. The online-only course (Renewable Energy and the Environment) boasted an enrollment of 600 last spring and teaches students about topics such as life-cycle analysis, climate change, forms of clean energy, and energy policy. One of the course requirements includes a “Do Something and Report It” assignment. For this assignment students must do a small project based off of course learning and then report it back in the form of a fact sheet, news article, PowerPoint presentation, or video. Previous projects have included videos showing students making solar iPod chargers, making biodiesel, auditing their homes’ energy use, or melting cheese on a tortilla using a homemade solar oven.

After completing the projects, Schmidt requires the students to watch their peers’ videos and comment on the presentations. The collective viewing allows the students to see different areas of action to which they can personally relate. Schmidt emphasizes that the class is not just for school, but for their life’s well being.

View the original post on Clean Energy Resource Teams’ website.

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4 thoughts on “Is There Phantom Power Usage In Your Home?

  • The takeaway for me from all of this is that modern computers and computer-like devices, as long as they are not desktop computers, use almost no electricity. He plugged in 11 devices, almost all of which can act as computers of a sort, and they maxed out at 195 watts total. That’s less than 20 watts per device, less than the power it takes for a 100-watt-equivalent CFL bulb.

    And when they were charged, they drew less than one watt each. That’s not a phantom load. That’s a rounding error.

    The lesson: don’t give a second thought to laptops, cell phones, and other handheld devices when it comes to their power usage. Focus on the important stuff, like heating and cooling, lighting, larger electronics (I would love to see his measurements for his set-top boxes, wi-fi router, and cable modem) and large appliances.

    • My wifi router pulls 3 watts. I have a wifi transceiver rather than cable router, it pulls 4 watts.

      I use a “boombox” for radio part of the day. It pulls only 4 watts with the volume turned up fairly high.

      I understand that our most problematic device seems to be TV recorders. This should be an easy to solve problem. They should pull only a tiny amount while in standby and no more than a laptop while recording.

  • I’m not sure I buy this completely. Couldn’t the draw simply reflect the devices’ normal power drain? Even in sleep mode the battery level on my Galaxy S3 drops by about 1% an hour. What I’d like to see compared is keeping the device constantly plugged in for a longer set period of time, say one week, to a similar length cycle of charging it up, unplugging it for a while, then re-charging it again after the battery has drained a bit.

    Then there are other considerations as well. I normally keep my phone plugged in all the time when I’m at home, mostly because who knows when I might need to leave unexpectedly and stay out for an extended period, and I wouldn’t want to have to go out with a phone that’s only half charged.

    • Altair…very good point that the devices when fully charged are still active and require a small amount to keep them fully charged.

Comments are closed.