Fun With The Kill-A-Watt

Posted by Artem Russakovskii on December 15th, 2007 in Personal, Stuff

Updated: December 19th, 2007

If you haven't heard yet, there's a cool useful little device that you can buy for about $20, called the Kill-A-Watt. You plug it into the power outlet, then plug something into it and observe various fun facts about the plugged in device, such as the power consumption, voltage, amperage, etc. I started plugging things in and recording power consumption that you can see below. Here are the results I got so far (updated often):

  • Vizio P50 HDTV 50" plasma
    • standby: 0-1W
    • on – perfect white screen: 450W (OUCH!)
    • on – bright screen: 350-430W
    • on – medium brightness: 250-350W
    • on – dark scenes: 200-250W
    • on – perfect black screen: 185W
  • Torchiere floor lamp with a 300W bulb
    • 1st torchiere – on: 272W
    • 2nd torchiere – on: 305W
  • Cell phone charger
    • no phone, no LED: 0W
    • no phone, LED on: 0W
    • phone charging (Samsung A900): 3W
    • phone charged (Samsung A900): 0W
  • Dell 90W laptop charger
    • no laptop, LED on: 0W
    • laptop on, screen on, already charged: 33W
    • laptop on, screen off, charging: 74W
    • laptop on, screen on, charging: 85W
  • Revlon 1875W blow dryer
    • low cool setting: 192W
    • medium cool setting: 231W
    • high cool setting: 251W
    • low hot setting: 408W
    • medium hot setting: 644W
    • high hot setting: 1520W (HOLY SHIT! Blow drying your hair may just be the most expensive thing you can do. Don't you have some baby seals to club?)
  • Braun WK200B AquaExpress electric water kettle
    • on: 1430W (SHITx2! If you like to constantly reheat your tea kettle, like some people I know, maybe you should switch to a regular stovetop one)
  • Rowenta electric water kettle
    • on: 1465W
  • Plain 2 slot toaster
    • on: 950W (and 8 Amps! If everyone just gets rid of their kitchens, we will have an instant green paradise)
  • Honeywell 51000 air cleaner
    • on – low setting: 57W
    • on – high setting: 94W
  • Honeywell compact fan similar to this one
    • on – low setting: 28W
    • on – medium setting: 36W
    • on – high setting: 45W
  • Panasonic MC-V5710 vacuum cleaner (10A)
    • on – 900W (8A, guess it's getting old)
  • Norelco electric shaver
    • plugged in – charging: 3W
    • plugged in – in use: 0W (apparently, the shaver can't charge while being in use)
    • plugged in – charged: 0W (no overcharging is done when you leave the charge on for too long)

Got any requests? Post and I'll try to fulfill and publish them here.

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Artem Russakovskii is a San Francisco programmer and blogger. Follow Artem on Twitter (@ArtemR) or subscribe to the RSS feed.

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  • Kevin

    I had heard that cell phone chargers always pulled electricity, even when device was plugged in. I wonder if they do and if those other transformer wall warts pull much electricity either.

  • Kevin, well, as you see above there's no consumption when nothing is plugged in, except to power the LED. It makes sense if you study physics 😛

  • Mantari

    For fun, do a refrigerator. (Measure the average over three days.) Then, clean the coils, and measure again. Post the results.

  • Jim F

    Keep in mind that the manual for the Kill-A-Watt indicates that you should let your tests run for a "period of time" ("the longer, the better") to get a "true indication" of actual usage of an appliance, which means that such appliances that cycle on and off could take up to a month to determine an accurate power consumption rate, in order for you to see how much energy you're using in a year. So, depending on how many items you have to test in your home (and how many others you buy throughout the year and test when you bring them home), it may take you almost a year to find out how much it's costing you.

    Upon reading the users manual for the Kill-A-Watt EZ P4460, it indicates that it uses 10Watts, which comes to 87.6KWH per year. At a low rate of 14-cents/KWH (in my area), that comes to 12.26/year.
    (Reference: http://www.ccrane.com/instruction-manuals/kill-a-watt-ez-P4460.pdf – I couldn't find the power consumption info for the P4400)

    So, to find out that your microwave oven display clock is costing you $2/year or a 4W night-light is costing you $3/year or that your 5W desk lamp is costing you $6 year (if these were all left on 24/7), you have used more power trying to determine how much you can save, than it cost you to determine the costs of those units.

    When you're doing your cost analysis, don't forget to add in the $20-$40 cost of the unit… after all, those pennies add up. Has anyone asked how much energy the manufacturer is using in a year, to build these units? How much is this adding to the "greenhouse effect" on the Earth's environment.

    And while we're calculating the costs to the consumer… it would be interesting to find out if the company received any federal grants to design & build the device and if they get tax credits/deductions for their contribution of an energy-saving device. If so, then we would have to determine how much this is costing the average taxpayer each year.

    How much would we all save if we threw out our computers? Instead of sitting here reading about how much energy we could save by buying one of these units and unplugging our microwave or toaster when not in use. Of course, that would lead to more landfill rubbish and the environmental problems that would cause… and the cycle continues… we're doomed?

  • Jim, first of all, the 10W rating on the unit is max, meaning it probably uses a less power to run.

    Second, I don't need to keep the unit running to get the average for most things as the power consumption is quite regular and doesn't fluctuate much. I then wouldn't leave it plugged in just to have P3 do math for me, I'm quite capable of multiplying consumption by the number of hours myself.

    As far as production costs to the environment. Consider this: if the people employed by P3 didn't spend their time making this small unit, which is probably on the low side of environmental production costs, they'd have to find a job somewhere else, potentially producing things far more harmful to the environment. The owners could have started a nuclear power plant in the parallel universe, you see?

    I think the point of this gadget is awareness. One person who buys it most likely will share it with friends. A blog like this will share results with hundreds. Not all is lost, Jim, cheer up.