EEVblog #1284 - How Bad Product Design Kills The Environment

[floobydust]

9V alkaline batteries are ridiculously expensive at $6-$7 each, per year.

BS. For 22$ you get 12pieces of 9V batteries that will last at least 2 years in properly designed smoke detector.
https://www.amazon.com/Energizer-Industrial-Batteries-Alkaline-Battery/dp/B000099SKB

I quoted $CDN from Home Depot. Amazon.ca is $2.67 each if I buy that box of 12 for $32 and they aren't knockoffs. But I don't use that many 9V batteries! WTF I have to waste $32 and the last straw was the chirping low battery alert at 3AM, so I'm choosing to destroy the power factor of the grid. Zero purchases or hassles for 4 years now over smoke alarms in the house. NFPA advises to replace smoke alarm batteries every year at Christmas.

I have filed complaints to an "importer" and UL over a mains-powered smoke alarm due to the capacitive-dropper being a cheap hot running POS and smoking and false-triggering the alarm. They ruled it's not a danger recall-worthy because the units are still detecting smoke ok. I have pics. The units have an aux relay contact for alarm bells, so extra power wasted as heat.

I saw a cheap chinese night-light with capacitive dropper, that shorts out the LED during daytime. They could have just left the LED on 

[Ed.Kloonk]

My two cents.

I've put in a few of these smoke detectors and replaced too many. I wish to Christ they would have a standard foot print access all smoke detectors so you don't have to wreck the ceiling when you replace it with a different brand.

Why do they fail early? 1, they're cheap and 2, rental occupants hit the thing with a broom stick to shut it up becuase they don't know how to cook without setting fire to food.

I've had renters hack the battery switch so the routine inspector might not notice it needs to be fixed for above reason.

I cringe a little bit when Dave waves the non-insulated screwdriver at the terminals. If it's 240 or ever had 240 in it, use sleeved tools. Please.

I've had renters buy/acquire the paint/reno covers for them too. Sometimes the 9V only ones are the solution.

[Ed.Kloonk]

The other reason I think these horrid things are so prevalent in Oz is because of Bunnings. That company is price driven on the cheapest shit and the real deal smoke detectors don't get a look in.

[gslick]

I just happened to have replaced the 9V batteries in the 6 smoke detectors in my house before watching this video. They had all been giving off low battery chirps for quite a while before I got around to dealing with the nuisance of replacing the batteries.

These smoke detectors are old enough (at least 15 years, maybe 20) that they are due to be replaced. Any thoughts on the models that are AC powered with a non-replaceable "10 Year" lithium backup battery? I like the idea of not having to deal with replacing batteries every year, as long as they actually last close to the rated 10 year lifetime. But the real question is, how bad is it that when the "10 Year" lithium backup battery expires you throw away and replace the whole smoke detector instead of just the battery? How wasteful is that? Or if the backup battery does last close to 10 years, is that somewhat near the lifetime of a smoke detector before it should be replaced anyway for reliability reasons?

[dzseki]

Given that domestic power consumption is overwhelmingly inductive (fridge motors, fans, wall-warts of all descriptions), the capacitive load of these smoke detectors might actually be the only thing in the house serving to “even up” the reactive load in the household...  I.e. I’m thinking that they may be doing the power company a favour...

most wall warts are switching supplies now, is a bridge rectifier on mains an inductive load?

Good question, which brings to mind the impact of bazillions of idle wall-warts, compared to merely millions of AC-powered smoke detectors.

wallwarts now have requirements on no-load power consumption and PFC above a certain size

Uncorrected SMPS mostly acts as capacitive load, the rectifier charges a capacitor afterall In some mediocre PC power supplies you can see an iron core yoke around the input, that is for "static" PFC.
But switcmode power suppies do worse: because they rectify the mains and the capacitor is charged to the peak voltage of the mains, therefore the diodes only conduct current when the capacitor's voltage is less than the actual mains voltage  v(t). Therefore most current is flowing when the sine is near at its peak (otherwise no current is flowing), this can lead to harmonic distortion of the mains, ie in flattening out the peak of the sine.

[SparkyFX]

The alternative of solely battery powered ones probably has the bigger impact on the environment, while the grid powered ones have the backup battery and depend on the grid. The value seems to be too low for battery salvaging and refurbishing.
OTOH last thing you want is the smoke detector catching fire because of bad design/part failure

Discussions about the environmental impact of grid power always suffer when it comes to the question if people speak about the current or future energy mix of renewable or fossil fueled ones.

A low PF just means more phase shift of current vs. voltage, which conventional meters do not measure, but still needs to be provided by the grid. It really is just about the metered value and actual current, not about the environment. Any inductive load on the same grid will do the phase shift to the other direction, so such devices need to be seen in context of the whole household.

[filssavi]

I think most of the confusion in this thread comes from improper terminology in the power systems field

While it is said that reactive power is generated/consumed, this is not really physically happening, as reactive power is just an effect that stems from the current exchanged between inductances and capacitances on the grid, these being purely reactive don’t consume any power per se (the resistance on the lines does, but the losses are much smaller then the whole reactive power)

The control of reactive power on the grid is of the utmost importance as it determines the voltage. For this reason several methods for “generating” and “consuming” reactive power need to be installed by utilities and grid controllers (e.g. field excitation control on wound rotor generators, synchronous condensers, statcoms, SVCs etc.)

As for the matter of the video, you must keep in mind that a single 150W fridge compressor (I’m assuming a power factor of 0.7 inductive) exchanges 45 var with the grid each cycle, this will offset probably dozens if not hundreds of smoke detectors

Last but not least businesses are charged for reactive power for 2 reasons:
1) it is a deterrent from the utilities, so that they have to install the minimum amount of compensation possible
2) it is a measurable quantity as opposed to the losses caused by reactive power (which are spread all over the grid)

[EEVblog]

The alternative of solely battery powered ones probably has the bigger impact on the environment, while the grid powered ones have the backup battery and depend on the grid.

The mains powered ones use exactly the same alkaline battery that last essentially the same amount of time. So the mains powered units saves zero batteries.

[EEVblog]

I cringe a little bit when Dave waves the non-insulated screwdriver at the terminals. If it's 240 or ever had 240 in it, use sleeved tools. Please.

I'm a professional 

[Muttley Snickers]

These smoke detectors are old enough (at least 15 years, maybe 20) that they are due to be replaced. Any thoughts on the models that are AC powered with a non-replaceable "10 Year" lithium backup battery? I like the idea of not having to deal with replacing batteries every year, as long as they actually last close to the rated 10 year lifetime.

An option many seem to overlook are smoke detectors powered by and connected to the security system if one is present. These are ideal for both residential and smaller commercial premises as the security system incorporates a backup battery anyway. Regulations changed down here a couple of years ago which meant that even these 12 volt alarm powered detectors required an onboard battery.

Some of the other benefits with alarm interfaced units were:
1. Option for both internal and external sirens to alert neighbours.
2. Notification of events to security monitoring or direct via SMS.
3. Ability to isolate or bypass problematic zones if necessary.
4. Ability to turn off the output powering the smoke detectors.

We generally used the Brooks or System Sensor brands but I've been out of the game for a few years now so there might be some other options as well.

https://www.brooks.com.au
https://www.systemsensor.com
 
 

[daqq]

Another solution: Use one of those crazy small tranasformers:

http://www.farnell.com/datasheets/65263.pdf

such as:
https://uk.farnell.com/block/vb-0-35-1-15/transformer-0-35-va-15v/dp/1711394

Size: 22x23x15 mm, 20g weight

[SparkyFX]

The mains powered ones use exactly the same alkaline battery that last essentially the same amount of time. So the mains powered units saves zero batteries.

Sorry, did not point this out correctly, the Lithium 10 year type vs. the 9V alkaline vs. the mains powered w/ 9V alkaline backup. The 9V type required replacement every 2 years or so, the Lithium 10year so far is just 3 years old.

Mine usually go off when i cook or forgot the pizza in the oven. My cooking skills improved a bit... and the habit to use a timer helped a bit too.

[Ice-Tea]

Going to agree with some others here: I object to the random mixing of VA and W. I understand your point but watching the movie you can leave with the idea that it's all the same. It's not.

Yes, the capacity has to be available on the net and yes, without compensation you're using up that capacity *but* you're not burning a Joule of fuel to generate a VA.*

* Yeah, yeah, the ohmic losses in the wiring and all that...

[mikeselectricstuff]

Another solution: Use one of those crazy small tranasformers:

http://www.farnell.com/datasheets/65263.pdf

such as:
https://uk.farnell.com/block/vb-0-35-1-15/transformer-0-35-va-15v/dp/1711394

Size: 22x23x15 mm, 20g weight

IME these things are terrible - very poor efficiency and they run warm enough to distort their  plastic case over time even with minimal load.

[filssavi]

Another solution: Use one of those crazy small tranasformers:

http://www.farnell.com/datasheets/65263.pdf

such as:
https://uk.farnell.com/block/vb-0-35-1-15/transformer-0-35-va-15v/dp/1711394

Size: 22x23x15 mm, 20g weight

IME these things are terrible - very poor efficiency and they run warm enough to distort their  plastic case over time even with minimal load.

Not to mention that the power factor of the transformer with such small loads might be just as terrible

[mikeselectricstuff]

Another solution: Use one of those crazy small tranasformers:

http://www.farnell.com/datasheets/65263.pdf

such as:
https://uk.farnell.com/block/vb-0-35-1-15/transformer-0-35-va-15v/dp/1711394
The datasheet mentions no-load losses around 1W


Size: 22x23x15 mm, 20g weight

IME these things are terrible - very poor efficiency and they run warm enough to distort their  plastic case over time even with minimal load.

Not to mention that the power factor of the transformer with such small loads might be just as terrible

[GeorgeOfTheJungle]

It takes 5W to charge a 1µF capacitor 100 times a second.

100*1e-6*((240*sqrt(2)-15)^2)/2 ~= 5.2 joules/s

Where are the other 15W up to 20 VA dissipated then, in 100R and the zeners? 15W are many watts, they should be quite toasty. No?

[Poe]

But Dave, you waste more energy than even a million smoke detectors.

n*m/60=Tmh
Tmh*p=Twh

Where
n = number of people viewing this video
m = number of minutes wasted by not editing
p = power consumption of YouTube viewing device
Tmh=Total man-hours wasted
Twh = Total watt hours wasted vs a polished/edited video

Assuming 100k views where 20 out of a 30min video is waffling..
100,000 * 20 / 60 = 33,333 man-hours wasted
33,333 * 10 = 333,333wh wasted

That's actual wasted power, not reactive, for ONE video.

[EEVblog]

It takes 5W to charge a 1µF capacitor 100 times a second.
100*1e-6*((240*sqrt(2)-15)^2)/2 ~= 5.2 joules/s
Where are the other 15W up to 20 VA dissipated then, in 100R and the zeners? 15W are many watts, they should be quite toasty. No?

@79.3mA and 1.36W total measured:
100R = 0.63W
So that leaves 0.73W for the zeners.
Ignore the load which is naff all.
Maybe a smidge in the cap ESR.
The rest will be copper losses down the system unless compensated for.

[Brutte]

I think most of the confusion in this thread comes from improper terminology in the power systems field

+1

Dave, please do not confuse Watts and Volt*Amperes.
These are two different animals, like apples and oranges.
You cannot add them, subtract or compare.

Please split the video into two parts:
-Part One: You are ranting only about low efficiency of this power supply (do not even mention "volt*amperes" word in this part).
-Part Two: You are ranting only about low power factor of this power supply (do not even mention "watts" word in this part).

By far the least profesional eevblog so far.
Very close to some YT blogs where people start to compare power(kW) to energy(kWh).
 

[Jr460]

Wow people have some crappy smoke alarms.

Mine is an old one that has the radioactive stuff in it.   Still works fine, i know the wife set it off a month or so ago cooking and not turning on the vent fan.   You couldn't ever "see" anything in the air, but the alarm went off.   No need to replace it if it keeps being that sensitive.   

One 9V battery and that lasts, and lasts, and lasts.   2 years plus out of one battery, yes I do test the alarm.

[coppice]

I think NANDBlog is right. The generator doesn't need to generate all the reactive power but only the active power + losses.

There is reason why commercial companies are charged in kVA. They aren't charged kW+"copper losses"

Where have you seen companies charged for kVA? Around the world. commercial users are normally charged for actual consumed (i.e. active) energy. In some places a commercial user's reactive power or power factor is measured continuously, and if its really bad (or sometimes if its really bad specifically during peak hours) the customer is charged a punishment factor on top of their active energy, to encourage them to improve their power factor.

[Domagoj T]

Where have you seen companies charged for kVA? Around the world. commercial users are normally charged for actual consumed (i.e. active) energy. In some places a commercial user's reactive power or power factor is measured continuously, and if its really bad (or sometimes if its really bad specifically during peak hours) the customer is charged a punishment factor on top of their active energy, to encourage them to improve their power factor.

This is Croatian power company price list for industrial consumers:
https://www.hep.hr/ods/korisnici/poduzetnistvo/tarifne-stavke-cijene-161/161
The table is an image so it won't translate, but the column "Prekomjerna jalova energija" (excessive apparent power) is what we're talking about.

Also this:
https://translate.google.com/translate?sl=auto&tl=en&u=https%3A%2F%2Fwww.hep.hr%2Fods%2Fkorisnici%2Fsavjeti-kupcima%2Fnaknada-za-prekomjernu-jalovu-energiju%2F579%23
Basically, if the customer keeps their power factor above 0,95, there is no penalty. If it drops below it, then there is a penalty.

[Jeff1946]

As noted in Dave's video, photoelectric detectors detect visible smoke.  Those based on radioactive sources produce ions in the detection chamber which produce a current between two charged plates.  Particles, including those to small to see, in the air decrease this current.  That's why I replaced the ionization detector nearest my kitchen which would often alarm when we were cooking with a photoelectric one.  No more false alarms.

[nctnico]

I think you should review how reactive power works. The 100MW is not generated by the wind turbine. You generate 5MW by the wind, and place a compensation on the power grid, that will generate the reactive power. It is just a big capacitor. The grid already has a bunch of inductive load, because of motors.

See my comment above.

Nope. Nandblog is right. Your reasoning doesn't make sense. If you input 100MW into 5 million devices then each device would dissipate 20W and -given the parts inside- something would go up in flames. But that isn't happening. This is the basic law of physics which says 'the amount of power going in is equal to the amount of power going out' in action. And no, the losses don't occur somewhere in between because your meter says there is about 20VA going into the smoke detector.

The windturbines only deliver the actual power but the current and voltage may be out of phase and/or have different waveform shapes. The only problem with too much out-of-phase / non-sinusoidal current is that the losses in the wires are higher and cores of distribution transformers may get saturated at lower power levels.