Should you be using batteries in your Smart Home devices?

In a previous post I tried to determine if my use of smart equipment was helping my increasingly green credentials (which I am striving to do). And my conclusion was it definitely is, but I still think I can do more by using appropriate technology with the right power supply. Here are my thoughts and, as usual, please feel free to comment/feedback! Our Community is the perfect place for this.

Battery-powered smart home devices

So this is a hard nut to crack. Whilst WiFi devices have done me proud, I really love the new Zigbee 3.0 devices, especially the Sonoff and Philips Hue devices which also seem to work with the Smart Life app (and natively in Apilio). Partly because they are small, unobtrusive and bullet-proof but also because the speed of response is just astonishing (see here for an over-enthusiastic video in my Apilio Community post). 

BUT, they all seem to use the CR2450 battery, for which I have really struggled to find rechargeable options, causing me a dilemma: it seems so wasteful and shameful to keep throwing away/recycling these batteries every year or so. Well, the good news is I actually just found out that rechargeable LIR2450 batteries are available now - yay! - but still not many charger options except this cute USB one which I am starting to test.

Cute Lithium Ion Coin Cell Charger that can be found at the Pi Hut

Mains-powered smart home devices

But surely it’s better if my devices are mains powered somehow, ideally via solar production so they can be entirely guilt-free, rather than experiencing the battery guilt? And even better, if the devices are on auto-upgrade and mains power supply, I can set and forget’em rather than worrying about devices running out of battery. 

Let’s see what I would need to make this change:

  • First, in order to use a power supply with my devices, I need to find a suitable adapter to wire the battery connection in my device so I can plug it into any outlet. This might not be easy nor pretty.
  • Second, I need an electrical outlet to plug into.
  • Third, I then have cables to hide/manage.
  • Fourth, I might have to consider how much bandwidth these devices are now using: I accept this may not be entirely true but based on my experience the powered units seem to send more data. For example, I have one mains-powered Tuya device that sends Apilio an update every time the light level changes by so much as 0.1LUX = very frustrating. So frustrating I actually decided to retire it early to reduce network traffic and save bandwidth. Removing it also led me to conclude I actually only need one light sensor to determine day-time light levels across my whole house as, surprisingly enough, it turns out that when it’s dark in the kitchen it’s normally dark everywhere. 

I’ve found making the change to wired smart devices is a good option when you find yourself replacing batteries very frequently, or if you can find a close outlet to plug your device into, or find a new position for it that still works.  

Batteries vs mains-powered devices: which ones did I choose?

So after trying to balance this in my IoT world, my conclusion is I will use rechargeable batteries ONLY in the low power units. It seems like the combination of low power electronics, small devices, low power networking and rechargeable batteries is the right one for me. 

I‘ve recently installed  an external solar array which should make this carbon/guilt-free aside from when the rechargeable LIR2450s eventually hit end of life. I guess I will end up recharging the LIR2450s more than I would have had to change out the CR2450s but hey, as Kermit the Frog once said “it’s not easy being green”. 

I’ve also seen some fantastic products emerging - the amazing self-powering switches seem fantastic and I can’t wait to try them.

For high use sensors, like frequently-used PIR triggers and where one may need to know light levels to the nearest 0.1LUX in real-time where there are no wired alternatives, I will stay with the lowest power devices I can find still using rechargeable batteries but higher capacity ones like AA/AAA/PP9.

By Dan @ Apilio

May 10, 2021
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