Is there a difference between kill-a-watt devices?

For basic questions of how much electricity an electronic device uses, is there a difference between kill-a-watt units?

We think our electric bills are higher than they should be, so we want to find out which electronic devices are the biggest culprits.

If we were professional vampire hunters, I can understand that durability, high accuracy and more data than kW-h would be beneficial. But I don’t think an armature hunter necessarily needs a fine level of detail or much robustness in data. I’m also fine walking over and looking at the thing, so I don’t need wireless access or the ability to monitor several things at once. On the other hand, I don’t want to burn the house down or start unplugging things based on bad data.

A random sample of the top search results on Amazon shows them selling for $55, $30, $20, $15, and $12. Harbor Freight has one for $20 (after the ubiquitous 20% coupon).

For the basic purpose of finding out whether a particular computer, console or appliance is unnecessarily running up our bills, does it make a difference whether we go with a simple $12 model or are we really that much better off “splurging” for the extra ten bucks into something ostensibly better? If it makes a difference, the largest appliances we’d be looking at are a freezer chest and the refrigerator. Most everything else is an entertainment-level device.

Looks like the $55 one can record a history of power consumption, while cheaper ones only display the current power draw, and the total since it was last reset. Also some can measure & display at 1W precision, others 0.1W. So if you are trying to measure the parasitic draw of an AC adapter, for example, a cheap one may display 0W while another may correctly display 0.4W.

There are also >$200 devices that install in the breaker box and measure the total power consumption, in real time, via wifi. I have a Sense but there are others. This is really the ultimate solution for understanding where the power is going.

ETA: There are cheaper whole-house meters now, apparently, this one is $100.

This PDF file compares the features of the three available models of the Kill-A-Watt branded power meter.

A device’s power consumption can vary over time, so if you’re trying to understand power consumption over time for a device, you need a meter that can tell you total kW-h for the time it was plugged in. For your purposes, any other data (volts, amps, phase, etc.) is extra. You can also do the cost math yourself based on the price per kW-h listed on your electricity bill.

Basically, the cheapest meter that reports kW-h is the best value for you.

Agreed! I bought a kill-a-watt over a decade ago. It is really useful. While it can report instantaneous (i.e., right now) levels for current, voltage and power consumption, what is best is the long term energy use, that is, kW-hours.

So, get one, and plug it into various electrical devices for, say, a full day each, and write down the reported kW-hr for each device. Even devices with small power draws will have tallies if they’re recorded for a full day.

I used one to find out that my 1970’s refrigerator used, on average, 360 W of power. It was running almost all the time, super inefficient. The power savings I gained by switching to a newer fridge that only used 60 W on average was enough to pay for the refrigerator, with a break-even term of about 1.5 years.

I then loaned my kill-a-watt to my company’s IT department. They were VERY reluctant to part with it when I had them return it. (Their boss was a micromanager who liked to know how much it cost to run the company’s servers, etc.)

Thanks; these sound as useful as I’m imagining them to be — and cost effective too.

So I’m finding that the basic $15 model will display “current power which ranges n 0.0W~9999W,” so scr4’s main concern is addressed. It also tracks cumulative consumption over time, resetting after 24 hours. For in-use computers I don’t particularly care what they do while in use, but the hours between are what I’m looking for; I can check, reset, then come back hours or a day later to get an idea of what they’re drawing while ostensibly sleeping.
And I’m sorry to complain, but when comparing myself to professional electronic vampire hunters, how come no one called me out on considering myself an “armature” one? I mean, it wasn’t that bad, was it?

IIRC, computers and monitors don’t take much when they’re sleeping. One big surprise for me was my computer’s speaker system, with four satellite speakers and a sub with a built-in amp. That thing is always on, always sucking 23 watts, costing $2.50 a month. The other big surprise was our TiVo. The hard drive and fan are always on, consuming 40 watts, adding ~$5 to our monthly bill.

Well, an armature is a part of an electric motor and electric motors consume electricity any you’re looking for the things in your house that consume electricity. So I just took your OP at face value and supposed that you’re hoping to locate all the armatures in your house.

I didn’t respond to your questions anyway, inasmuch as I am as armature on this subject as can be, and I know absolutely nothing about it. :smack:

So what happens if you plug in a Kill-O-Watt meter into a Kill-O-Watt meter? How much juice does one draw if used continuously (such as a whole-house unit)?

A Kill-A-Watt meter shows zero amps and zero watts when there’s nothing plugged into it that’s using power. But the meter itself surely uses power. So if you plug a Kill-A-Watt meter “A” into Kill-A-Watt meter “B”, and then plug meter “B” into the wall, meter"B" would show the power consumption of meter “A” (together with anything you plug into “A”). It’s likely that meter “B” would still show zero in this case because the power consumption of one of these meters is very low compared to the amount of power they are designed to measure.

I don’t know if there are different types but my simple device is powered by 2 little watch batteries, which power the display. When I’m not using the device I just pull the batteries out. They seem to last 5-10 years this way. So I don’t think the meters draw power from the outlet, so you wouldn’t see anything plugging them into each other. Yes they use power but from their own batteries.

Hmm curious - I have an old Kill-A-Watt labeled P4400. However, it only reads 1W granularity, not a tenth of a watt as claimed in the wiki article, and, indeed shown on youtube videos. They must have changed the specs on the thing without changing the model number at some point.

Biggest gripe I have about it is that it’s designed so that it covers both outlets in the receptacle when you plug it in, even when plugged into the top outlet facing up. You have to scrounge around and find an extension cord if you are using both outlets.

Some of the meters are stating their max rate at 16 amps. Some do not list what the max rate is. That is important you do not want to burn up the meter.