The Topic of Power Saving and IOT

I regularly use Smart Sockets to save power on various devices – been doing it for years and never given it a second thought.

Smart Socket

I was just today pondering the fly-killer we run all day every day in our living room. Now, let’s say we have a standard LED UV fly killer… I just checked and these use around 3W. Well, they are utterly useless in daylight as the flies head to the light – and if the fly-killer is no-where near as bright as internal room lights or indeed sunshine, there is no incentive for them to head off to their death when the ceiling or window is more interesting.

3W may not sound a lot but do the math – that ends up at 26KW/H over a year.. and right now in 2022 that’s not quite as irrelevant as it was a couple of years back. So, I hit on the bright idea of attaching a SMART SOCKET. Let’s for now ignore the likelyhood that the Smart socket cost probably outweighs the potential savings – indeed why don’t I just say “Let’s say you have an old Smart Socket lying around”.

Good – BUT the average WiFi Smart Socket uses maybe 1-2w (if you make sure the little LED LIGHT if fitted is turned off). So really you’re not even saving that much. But hold on – what about Zigbee Smart sockets? It seems these take as little as 0.3w – THAT’s more like it.

Remember old-fashioned mechanical timers - pre-covid they were maybe €4 Euros at any Chinese store - now up to €6 even on Black Friday sales

Let’s back up a little – what’s wrong with good old-fashioned wall timers? The really cheap mechanical ones – a few € (Euros in my case) are uttely useless for any long-term project because they are blissfully unaware of power cuts – the first cut and they are out of sync and this accumulates. It amazes me the number of people who don’t know this.

Alternatively there are commonplace LCD wall timers – which have internally a real time clock – which rarely handles summer/winter time correctly but at LAST it seems the EU (for example) are about to ditch that past-its-sell-by-date bi-annual changeover – these timers will be fairly low power but for the life of me I can’t find it printed on the back of any of mine. But it seems we can forget these timers – according to this site – their mechanical timers typically take 1W per hour, the LCD versions take more.

This subject was merely something I’ve thought about over the years but never progressed. There is of course another element – in the case of UV lights – reducing the number of active hours could increase their lifespan and that applies to both the old tube-base lights and the more modern LED-based versions to a (possibly) lesser extent.

Of course if we’re talking about something more power-hungry like a heater or motor or powerful lamp – that’s another story.

Phone FAST chargers

In the area between ultra-low-power devices and say phone/tablet chargers – there could be yet another angle to this…. using, for example, a Zigbee wall socket, if it were possible to limit the phone charge to 85% – this could actually be worthwhile – the cost of the socket would still seem to be a problem unless you factor in the phone battery life – improved by NOT charging to 100% every time.

Now, on a typical Android phone it should be possible for the technically inclined to simply use TASKER to send an alert to whatever controls your Zigbee devices and have the wall charger turn off when the battery is at the desired less-than-100% charge. There are many articles out there on the benefits of NOT fully charging phone batteries.

Comments welcome as long as they aren’t rude 🙂

See comments below about Samsung S22 Ultra charging – solved for me – solutions for non-Samsung phones welcome… where would I be without helpful subscribers 🙂


6 thoughts on “The Topic of Power Saving and IOT

  1. For your fly killer application, a very simple approach might be to use a normally-closed relay to switch its supply, with the relay coil connected directly to a (small) solar panel. When it’s light, the relay turns off, and when it’s dark, it turns on. Might take a bit of fiddling to get it right, but the overhead power consumed is zero!

    1. As always there are umpteen approaches to any given problem. Of course at this time of year there is virtually no sunlight (I’m in the UK – Northeast – over Christmas) and back in Spain the fly killer is a long way away from the outside window – but I’m sure there’s some logic in your solution depending on the circumstances… never hurts to think about alternatives….

  2. I use the Samsung features for it. Limiting the max total charge, but also Bixby Routines to enable / disable super/fast charging depending on the time and location. During the day or when I’m not at home it’s on because then I’m usually in a hurry if I try to charge, and during the night or when I’m at home it’s off.

    For device settings and device control Bixby Routines are pretty useful and powerful.

    1. Ok, that’s very good – now set to 85% max: settings – battery and device care – battery – more battery settings – protect battery (if ticked only allows up to 85% charge). That was easy… Works on my S22 Ultra – will try to set on my wife’s S21 Ultra later today.

      Eventually found routines – they’ve moved it all around… many web articles are wrong.

      I did a search for modes and routines – routines – added one – if > 11pm and < 7am, disable superfast charge and fast charge - i.e. I can leave it on normal charge overnight. That's helpful - but only to Samsung S22 and most likely S21 and S20 users.. not going to work on the miriad of other phones out there (I don't want to turn into an S22 snob....)

  3. Like you I worried about leaving my phone on charge overnight (geek overthinking), I use Home Assistant, it recognises my Samsung phone and reports its charge status. I plug my phone into a charger controlled by a ESP8266 and press a button to “activate” charging (I can also activate it from Home Assistants interface), When my phone reaches 90% home Assistant turns the charger off.
    Its been working well for 6months or so.

  4. Hello!

    I hope you are well.

    For battery-based computers there are some programs that limit their battery charging to whatever percentage the user would like (around 80% seems, as you have pointed out, the best range as far as battery life versus off-grid endurance, for most usage scenarios). An example is Aldente, for Macs. The Mac OS activity monitor reports its power use as negligible.

    Another option are devices that sit between the charger and the chargee, and which communicate with both devices to regulate the final battery charge and sometimes even the charging power-time profile. I employ one called Chargie, which requires an app, so mobile phones only. Not sure what its power usage footprint is.

    Cordial regards from Brasil.

    Marco A A de Oliveira

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