SmartThings Motion Sensor (2015) case with AAA batteries

thingiverse

This is a 3D printed housing for the SmartThings Motion Sensor (2015) that takes 2 AAA batteries, instead of the single CR2450 button cell battery of the original case. The 2 AAA batteries combined should provide a significantly increased energy capacity of over 2000 mAh, compared to the ~600 mAh of the button cells, and for only a fraction of the price. I was sick and tired of replacing the costly CR2450 batteries that these ST motion sensors use. The good brand ones cost around €1-2/each and last for about 6 months if you're lucky, while the cheap ones from Aliexpress can be had for as low as 30 cents/each, but they are typically crappy and die in a only few months. On the contrary, AAA alkaline batteries are much cheaper (eg. Ikea sells a pack of 10 for €1.79 with a capacity of 1100 mAh) and 2 of them wired in series provide the same voltage than a single CR2450 and more than 3x the capacity. So removing the need to buy button cells to keep these sensors running is clearly a win. This printable case is of the exact same width and height of the original, and only a few millimeters deeper. Note that it is not a full replacement for the original case but instead it only replaces the white enclosure, and it's meant to be fitted with the original back plate. The wall mounting plate can also be used with this new case. **Note**: these ST motion sensors are crap anyway. They are totally energy inefficient, give false positives from time to time and often they just go bust and start reporting motion even within a sealed box. Don't buy them, there are much better options out there, but if you already have them then this printable case can ease the pain a little bit. I just wouldn't rely on them for anything critical.