[cushychicken]

We used to use those Kill-a-Watt probes at work to classify smart home device power draw.

Emphasis on "used to". They are not very accurate at all, and the sampling interval over which they take data on wall power draw is slow enough that you will miss important changes in current draw on your DUT. We have since switched over to expensive, calibrated Agilent power analyzers with better time resolution.

The post is well intentioned, but I challenge his data collection methods. His tools are not up to the task he has set himself to. It is not nearly as simple as the folks who sell Kill-a-Watt's would have you believe.

[a9h74j]

A EE video[1] shows such a bad power factor on a mere smoke alarm that the VA reading is 20VA for less than 1W actual consumption. An unsuspecting "power meter" might overestimate actual dissipation.

[1] https://www.youtube.com/watch?v=_kI8ySvNPdQ

[Bedon292]

Do you have some of that data available? I think his data does seem off, but all these always on devices have to be costing something right? Curious what that cost actually is.

[TeMPOraL]

> but all these always on devices have to be costing something right?

They probably are; that depends on how badly they're designed. But that doesn't mean they should.

Consumer devices aren't usually as efficient as they could be with some more design work, which I think makes people have a wrong reference point about how much power is needed to do things. As a counterexample and a way to reset the reference, consider e.g.:

- That there exist radio devices that are designed to run for years off a single CR2032 battery.

- That there are microcontrollers that can still execute your code while drawing nanoamps.

- My 9 m.o. kid has a plush moon with a string attached to it; when you pull it, it plays a loud melody (that part is mechanical) and flashes LEDs for ~30 seconds. Both are powered from the mechanical energy of your pull.

The way I see it, a typical device on standby and/or a typical wall wart not charging anything shouldn't pull more than some micro- or even nanowatts. So they shouldn't cost you more than a hundredth of a cent a month each. Now of course they do, there are probably some engineering constraints here (like more complicated devices wanting to keep RAM powered), and there are definitely business constraints (low-power design is more expensive). But to me, a device whose standby mode is noticeable on the power bill is simply broken.

[cushychicken]

I don't - it was collected for work, and I'm not allowed to share it.