SmartThings Motion Sensor (2015) case with AAA batteries

thingiverse

This is a 3D printed housing for the SmartThings Motion Sensor (2015) designed to replace the single CR2450 button cell battery with two AAA batteries, providing significantly increased energy capacity of over 2000 mAh compared to the ~600 mAh of the original case at a fraction of the cost. Replacing the costly CR2450 batteries that these ST motion sensors use was getting old. The good brand ones cost around €1-2 each and last for about six months if you're lucky, while the cheap ones from Aliexpress can be had for as low as 30 cents each but are typically crappy and die in a few months. On the other hand, AAA alkaline batteries are much cheaper - Ikea sells a pack of ten for €1.79 with a capacity of 1100 mAh - and two of them wired in series provide the same voltage as a single CR2450 and more than three times the capacity. This printable case is identical in width and height to the original, but only a few millimeters deeper. Note that it's not a full replacement for the original case, but instead replaces the white enclosure, designed 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 energy-inefficient, prone to false positives and often go bust, reporting motion even within a sealed box. They're not reliable enough for critical applications. If you already have them, this printable case can ease the pain, but it's best to consider better options.