Hey companies making sensors and remotes!
(for smart home/home automation and the likes).
If you can make a sensor microscopic – fine
If it needs to be portable – fine
But if it is rather small, but still visible you are not doing anyone any favor by making it as small as possible with a coin cell battery that runs just a few months or even less.
If your sensor can run for years and years on a pair of AA batteries, by all means use these! I want either a microscopic sensor – so small that i don’t see it or one with a battery that lasts forever.
The middle ground is crap. It’s still big enough that i see it and bothers me and has short enough battery life that bothers me.
Why would i want to have a slightly smaller sensor with much much less battery life? Do you think i like having 50 sensors/remotes etc with 6 months of battery life in my house such that every few days something stops working because of a low battery? Of course i don’t!
Plenty of devices are touting around ultra low power. Great! but it needs the other half of the ying-yang: ultra long battery life.
Why coin cell batteries suck:
-they have small capacity: a CR2032 has 14 times less than a pair of AA cells
-they are small and difficult to handle for many people, especially if you need screwdrivers pried in small indentations to open the box
-they exist in sooooooo many variants and many are used in sensors
-they are hard to obtain: the local supermarket has them for even 5 euros a piece
-they are more expensive per capacity: best case a CR2032 cost as much as one AA
So don’t use them unless the thing that uses it has to be as small as possible because it is portable or has to fit in some place. Otherwise, go for AA all the way! So:
Stop using coin cells in non portable sensors!
Example 1: Window or door sensor
This sensor can sense if a window or door is open or close. On the left: a commercial sensor operating on a CR2032 coin cell. On the right: my diy sensor running on 2xAAA for 5 times more battery life. Both are in the size region where they will be visible on the door/window frame but are not intrusive. The one with the bigger battery is way more comfortable to use, since its battery has to be replaced 5 times less often.
Dimensions on the chart are cm btw.
Example 2: Motion sensor
Left: commercial motion sensor with a CR2450 battery. Right: my diy multi sensor module which covers motion, temperature, humidity, pressure and light level and which is running on a pair of AA batteries which will last 5 times longer than the one on the left.
Both sensors are sufficiently large to be observed, but not large enough to be intrusive. The one on the right with the bigger battery is far more comfortable to use, since it requires the battery to be replaced 5 times less often.
Example 3: remotes
Left: commercial 5 button remote from ikea running on a CR2032 battery. Middle: the same remote control has been optimized for running on a pair of AAA batteries, lasting 5 times longer. Right: a diy remote control with three buttons which also runs on AAA batteries.
Conclusions: use AA or AAA batteries
The sensor or remote control nodes will be barely any bigger than the ones with coin cells and will be far more comfortable for the user who will be disrupted far less often to replace the batteries.