kill-a-watt meter, the cat's meow

[eljefino]

Inspired by the dehumidifier thread I got a Kill-a-watt meter on ebay. Hint, look at shipping charges, one vendor is only ~$4 and has the lowest total price.

Anyway I'm playing with this thing and it's the bee's knees. My compact flourescents really are at rated input. (Thinking of the seinfeld where they analyzed "fat free" food at a lab, it was too good to be true, Elaine kept saying "Fat! Fat!")

Am not yet hunkering down for a 24 hour spell with the fridge. Will, on two days with similar weather, run the thing, then clean the coils (they need it) and run it some more. Something has been increasing my kWh and I want to find what.

Have found my computer monitor uses more power to make brighter pictures. Am considering a darker windows scheme/ wallpaper.

Have found that, churning away, my Emachines tower only sucks 120 watts. "Idle" is 60 watts. 400+ watt ATX power supplies seem like so much hype. Furthermore, sizing a UPS is handy with this info.

Wonders never cease. The basement deep freeze draws 180 watts, which a cheap car inverter can supply.

I can't believe I've never seen these things in hardware stores etc. They'd make an awesome christmas present for anyone. Thanks BITOGers who've recommended this thing.

 

[oilyriser]

Does it give the sample rate? ie. how many measurments per second.

 

[Al]

quote:

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Originally posted by oilyriser:
Does it give the sample rate? ie. how many measurments per second.

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here's what it measures.

I'm sure its many times a second. What is your concern..which readings are you concerned with?

This thing is great. You can usually get it for 25 bucks including shipping.

 

[chas3]

the basement deep freeze might draw 180w but startup current might be 3-4 times higher. sometimes those cheap inverter's cant supply the current the motor needs to get started.

 

[eljefino]

Seems like it samples 2x a second.

Also yanking a plug sometimes gives an "interim" reading before going to zero, so there's some minor "softening" of the reading. Might not be the best way to see the peak reading of a motor starting for example.

 

[oilyriser]

Things with switching power supplies, like CF lamps, computers, and some microwaves will have a choppy current draw, so the meter has to take many samples during each a/c cycle to get an accurate reading. If it's correctly reading the CF bulbs, then maybe it's good enough.

I saw something like this on sale at Canadian Tire a while ago, but haven't seen it since.

 

[Virtuoso]

I wouldn't mind picking one of these up - I'd love to see what kind of current some of my things use.

 

[Mark in NY]

I have had one of these kill-a-watt things for 2 years. It has certainly been worthwhile.
I have been able to reduce my annual elec consumption by almost 20% in that time.

so far-

-3 CRT computer monitors rplcd by LCD
-more efficient CPU/motherboard combos installed
-all incandescent bulbs in the entire house rplcd by compact flour.
-xmas lights replced by LED light strings
-more efficient airconditioners

more to come since cost here is now at 20.1 cents/kwh and peak oil is rapidly approaching !!

 

[Master ACiD]

ive also got a kill-a-watt metre, ive had it for years. its so great for power outages and running on generator.

 

[rjundi]

I liked my kill-o-watt meter.

It was my power meter last summer that only registered a $75/month power bill. The power company caught up with it and replaced it. My bill jumped to $110 and then $150 with baby added

The worse was they applied a factor 6 months back on my discounted powerbill to regain their "loss"

 

[Razl]

I've let a few people borrowing after hearing their gripes about their electric bill being so high. I was surpised to discover my phanton loads added up to about 200watts. That's about $20 a month I was paying just because things were plugged into an outlet. I now have almost everything on a power strip and turn it off by the power strip so it truely draws no electricty.

My phanton load is down to about 50 watts ($5/month). Things like the modem, router, voip, alarm system, and timers need to be on 24/7.

Electric companies should be handing these things out to new accounts like phone companies hand out directories.

 

[XS650]

quote:

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Originally posted by Razl:
I've let a few people borrowing after hearing their gripes about their electric bill being so high. I was surpised to discover my phanton loads added up to about 200 watts.

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Razl, what were the biggest ones?

I went hunting for vampires about 8 years ago in my last house and found at least that many watts. Volt Amps actually, my home made setup measured Volt Amps instead of Watts.

My favorite was my early Dish Sat reciever. It used 50 VA turned on and 50 VA turned off.

 

[brianl703]

I think cable TV converters are the worst for phantom loads. Especially those old Scientific Atlanta 8500 and 8600 series boxes. They run really hot and use a linear power supply.

 

[Razl]

quote:

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Originally posted by XS650:
My favorite was my early Dish Sat reciever. It used 50 VA turned on and 50 VA turned off.

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NICE

From what I remember:
TVs ranged from 5-35 watts
CRT monitor (sleep) 20 watts
Cable box 10 watts
nightlight 7 watts (on without photosenor)
VCR 5 watts
Stereo 4 watts
Computer 2 watts
microwave 2 watts


I know transformers are really bad offenders (warm to the touch = inefficient), even little things like alarm clocks that only drew a few watts were replaced with battery clocks.

 

[eljefino]

Cleaning my dusty fridge coils did diddly squat. Will now try selective warming... I'm one of those guys who set their freezer portion to "max cold" and as some know, the fridge has one thermostat sensor in the fridge section and the "Max cold" thing is just a percentage diverter between the two boxes. Much tweaking of different knobs will reach my target temps.

I have already set up a power strip for all my camera/ camcorder battery chargers etc. I kill the strip when something's charged and leave all the widgets plugged in out of laziness... but the strip master switch kills this.

 

[JHZR2]

I love my kill-a-watt. I got two from a small conservation outfit from somwhere strange, HI or someplace... $42.95 for two with free priority shipping IIRC, it was a month ago now.

I love it. I have one permanently hooked up to the dehumidifier to see how much energy thats pulling down/how often it is running), and one that I use everywhere else.

I have found that my TVs, an old RCA and a 2002 panasonic 32" both take about 2-3W. 'touch' lights take about 1W at idle. The dehumidifier takes 1W at idle, but the dial-control window A/Cs take 0. Id venture to guess that some of the digital control ACs might suck some power at idle, but my only digital control one is a 240V, so I cant test it.

Ive yet to test my microwave, but anything with a clock is likely pulling about 1W. I need to test my mac mini and laptop, Id venture to guess that they are quite efficient.

I'm not so sure that Ill replace anything based upon draw, but itll definitely help me to decide how to replace things when I need to...

JMH

 

[JHZR2]

quote:

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Originally posted by eljefino:
Cleaning my dusty fridge coils did diddly squat. Will now try selective warming... I'm one of those guys who set their freezer portion to "max cold" and as some know, the fridge has one thermostat sensor in the fridge section and the "Max cold" thing is just a percentage diverter between the two boxes. Much tweaking of different knobs will reach my target temps.

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My refrigerator died in late July, and I got a new GE side by side. It is much more efficient, and it is nice in that it has a temperature sensor to tell me the actual temp in both the refrigerator and freezer. I dont think it can selectively cool one or the other though... not sure how that works.

I have mine set at 0 in the freezer and 37 in the refrigerator. I find that typically the freezer is at 0, and the fridge is at 36.

JMH

 

[XS650]

quote:

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Originally posted by eljefino:
Cleaning my dusty fridge coils did diddly squat. Will now try selective warming...

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I'v read that other places but didn't want to prejudice your test.

It's one of those things that has to be making a difference, it's just too small a difference to easily measure. Cleaning the coils is still the right thing to do.

 

[JHZR2]

quote:

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Originally posted by XS650:

quote:

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Originally posted by eljefino:
Cleaning my dusty fridge coils did diddly squat. Will now try selective warming...

---

I'v read that other places but didn't want to prejudice your test.

It's one of those things that has to be making a difference, it's just too small a difference to easily measure. Cleaning the coils is still the right thing to do.

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Isn't the point that cleaning the coils will reduce how long the compressor runs, not how much energy it will consume on a time-specific instance?

Unless all other conditions are identical, and you test over, say, 24 hours, I dont see how the test could be valid.

Case in point: when my old refrigerator was working fine, it would run on and off, like any refrigerator does. When its coil cooling fan died, the compressor would run nearly indefinitely, causing it to scarf down a LOT of electricity. Sure, if the fins werent cooling as efficiently because of dust, some portion of the thermodynamic cycle might not be running at optimum, and make the compresor have to work harder (or even have two phases a the compresor inlet), but this is irrelevant in terms of energy usage compared to how long the compressor is working for to achieve the required amount of cooling.

I guess the analog would be:

If cleaning the coils made the compressor need to do less instantaneous work (read by instantaneous watts on the kill-a-watt), you would see a change something similar to:

original - 975W
clean - 950W (if you were really lucky and moved some portion of your refrigeration thermodynamic cycle around due to the cleaning)

However, if it was related to how long it would need to run (what I think is the strong function of cleaning the coils), you would have that:

original W =~ clean W

However, given nearly identical conditions, you woulkd also get that:

original W*h > clean W*h

This is an analog to my broken cooling fan issue, with coils under a refrigerator with no cooling fan being an approximation for extremely dirty coils with minimal heat transfer coefficient.

So, all in all, I wouldnt be so sure that you arent saving yourself a lot of money - Id ventre to guess that if you got a decent anount of dust off of the coils - that your refrigerator is running less and youre saving $$$

JMH

 

[eljefino]

So what you're saying in other words is, the dust insulates the coils a little, so between compressor cycles, the coils take longer to cool down but eventually give off all the heat that's put in 'em, before the compressor kicks on again?

BTW, I did the test over two consecutive 24 hour periods. Ambient weather and door-opening variables were similar.