Kill-o-Watt

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Flack
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Kill-o-Watt

Post by Flack »

While cleaning out my desk drawers I found my old Kill-o-Watt. The Kill-o-Watt is a device that you can plug into the wall, plug another device into, and get information on how much electricity the device is using. The Kill-o-Watt costs around $30, give or take.

By pressing the different buttons on the front of the device, the Kill-o-Watt will tell you how many amps or volts a device is using, but the reason I bought it was because it'll also tell you how many watts something draws. Divide the watts by 1,000 and you get kilowatts, which is how we get billed by the electric company. Take a device's watt usage, divide by 1,000 (to get kilowatts) multiple by 24 (hours), and finally multiply that number by your kWh (kilowatt per hour) rate to calculate how much a device costs to leave it on all day. Multiply that number by 30 and you can estimate how much it would take to run all month.

As a kid, my parents were always telling me to turn off the light in my room when I walked out. I checked my electricity bill and I currently pay $0.074 (almost seven and a half cents) per kWh. Using my formula, I determined it costs 18 cents a day to leave a light on ($5.33/month).

To expediate all that math, I created a Google Sheet with the formula built in. All I have to do is copy the formula to a new line and enter the watts of another device.

I have multiple Raspberry Pi 3s that I leave running pretty much 24/7. I plugged one of those into the Kill-o-Watt and was surprised that it was only pulling 2.2 watts. That's less than a penny per day, and only about 12 cents a month. On the other hand, the 21" monitors they're plugged into pull 50 watts each, which figures out to 9 cents a day and $2.66/month. The three monitors I leave running 24/7 are costing me close to $8/month. Not the end of the world, but interesting to know.

I also remember my dad telling me to turn the TV off when I wasn't watching it. I have an old Visio 46" in my office that I decided to test. The rating on the back says 200 watts, but Kill-o-Watt rated it at 220, which is 39 cents a day or $11.72/month. Perhaps more interesting was the fact that with the television turned off, it still draws 1.2 watts. That's only 6 cents a month and it would take a lot of those devices to affect your bill, but I still found it interesting. The PS3 I have hooked up to the TV draws another 1.1 watts while turned off. I guess these things could add up.

The last thing I tested was the portable electric heater I have out in my workshop. It's one of those 3' tall ceramic heaters. I have always heard that it takes a lot of electricity to generate heat, and that was the case here. The heater pulls a whopping 1,375 watts. That's $2.44/day or $73.26/month. I know a lot of people who sneak these things under their desks at work and leave them on year round.

One other feature the Kill-o-Watt has is average usage based on a period of time. This is good for things like refrigerators that use a lot of electricity when the motor is on, and not as much when it's off. Using the average button, it'll monitor watts over a period of time and give you the average.

I have the three monitors on my main computer set to never go to sleep and I've decided to change that based on the Kill-o-Watt's findings. Between that and the other three monitors I've been leaving on 24/7, the Kill-o-Watt will pay for itself in about two months. A lot of these things are just common sense, but I find the numbers interesting. Also, I found it interesting that my old C64 power supply used 22 watts, but a Raspberry Pi running a C64 emulator only uses 2 (and the new THEC64 only uses 4), which in theory is an argument for moving to modern technology.
"Jack Flack always escapes." -Davey Osborne

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AArdvark
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Re: Kill-o-Watt

Post by AArdvark »

This is one of those devices, like the stopwatch function on a digital watch, that will start to make you obsess over being more efficient. It sounds like a slippery slope, my friend.
I remember obsessing over wall warts and night lights when I bought my first house, trying to reduce the electricity vampires. I spent a couple months unplugging everything when I wasn't using them. I had a lot of stuff on those power strips that I could turn off, really off, not stand-by. If I saved any money during that time I don't know about it.

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Ice Cream Jonsey
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Re: Kill-o-Watt

Post by Ice Cream Jonsey »

Dang, I leave my monitors on at night and never really gave it a second thought. I'm gonna start turning them off. You're a good man, Flack.
the dark and gritty...Ice Cream Jonsey!

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Jizaboz
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Re: Kill-o-Watt

Post by Jizaboz »

Oh wow that is cool. I had no idea such a home device was a thing marketed for this purpose.

These days the local power company replaced my meter with a "smart meter" a couple of years back and keeps
sending me spread sheets just showing me all of this magically. It's all completely accurate too..

- Inefficient heating detected (Yup, 1960s baseboard heaters. GOT ME.)
- Inneficient cooling detected. (My outdoor and indoor system for cooling is over 30 years old but still runs)
- Lightbulbs before I replaced them with modern ones at first. They even sent me free ones to use and be like "SEE?!"
- Turn off computers or use power saving mode. (Yup. Got me again but that ain't gonna happen.)
- And the weirdest one: "Small laundry loads detected. Please consider washing and drying large loads."

The wild thing is despite all of that AND it saying I should probably insulate my windows and such again I STILL have "better than average" usage efficiency rating. Makes me wonder WTF other people are doing.

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Jizaboz
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Re: Kill-o-Watt

Post by Jizaboz »

Ice Cream Jonsey wrote: Thu Dec 10, 2020 8:07 pm Dang, I leave my monitors on at night and never really gave it a second thought.
Living on the edge.

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The Happiness Engine
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Re: Kill-o-Watt

Post by The Happiness Engine »

I used to do these calculations by hand for a few things before I snagged a Kill-o-Watt. My two memories:

College roomates whining for me to turn off the lights when I left a kitchen. Me flipping them a quarter and saying "I paid for this light to be on 24/7 for the rest of the month, you can't turn it off."

A friend earnestly asking me to solve a dispute with his girlfriend about whether he could leave his PS4 paused all afternoon and come back to it later because the game DIDN'T HAVE SAVE ANYWHERE (emphasis ICJ). Did the sums and determined "Well, it's costing you about $10/month. It's up to you if that's a problem or not."

What I've mainly found is my old LCD and my speakers draw a lot of power, even when idle, if left on overnight. The PC not so much.

The one IMPORTANT[1] bit is to remember to divide your total bill by KW/hrs so you include elec, transmission, and bullshit fees and not just the partial cost!

[1] This WILDLY doubles your cost from 65 cents to a $1.30, so important may be in the eye of the beholder.

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Tdarcos
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Re: Kill-o-Watt

Post by Tdarcos »

Back when I was over on Baltimore Avenue, I originally got into a discussion with my Landlord, who discovered I ran two computers and two monitors, sometimes 3, and was unhappy about the extra electricity.

I said, look, a computer uses about 50 watts and the monitor about 50, each that's 200 watts which means it uses 5 KW a day, so since I'm not watching a TV that should cover one, so I'll pay an extra $15 a month. Then he had no problem. I almost never used three computers excepot when doing tests or experiments.

On a different tack, I had to learn lumens to know how much light a Compact Fluorescent or LED light bulb generated, and the correspondence is 16 lumens per watt incandescent, e.g a 40 watt incandescent (hot) bulb is 640 lumens. So to get the equivalent of 100 watts hot (I needed a lot of light to read) i needed about a 1600 lumen bulb. A CF in that luminosity is ~26 watts. A 100 watt hot bulb was about a quarter, maybe 30c. But they do burn out relatively quick. A 1500-1600 lumen bulb (23-26 watts) costs about a buck and a half. But, even though I'm not paying for electricity, using a CF means it will last a long time.

However, I decided to get my feet wet and try an LED bulb. And those are very expensive, about $9 each. But, if I was paying for electricity, it would be worth it, because a 1600 lumen LED bulb only needs 13 watts! And while a CF is supposed to be good for 10 years, you can apparently get 20 on an LED, IIRC. So, it made sense for me to buy two of them, and have the landlord put them in the ceiling lamps/, since I could never have reached them - and I hated when they would burn out as it left the room partially dark. So I turn them on and BOOM! It's like being in bright sunlight. As such, I normally used a hand-held lamp and only used the ceiling lights when I really needed extra brightness. I'd never had the equivalent of a 200 watt light source before.
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AArdvark
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Re: Kill-o-Watt

Post by AArdvark »

I counted all the wall- warts plugged in in my house and stopped after twelve. Dammit, now I feel guilty about all the starving appliances in China.

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