EnOcean NodOn Batteryless Door/Window Sensor

Most opening sensors are battery operated, often with poor battery life, which makes no sense when used with reliability and/or security in mind (alarm system, etc.). The EnOcean technology is built to harvest energy from the environment, but the standard contact sensor from their product line works using a solar panel. This hardly works when you close your shutters and leave for an extended period because the sensor is left in the dark.

NodOn (an EnOcean OEM) came up with a solution: EnOcean Battery-free Invisible Opening Sensor. This sensor works using a spring, activated by the mechanical action of opening/closing a door or window (see images for how it works). However, this design comes with a catch: The user is supposed to insert the sensor into the gap between the window and its frame, but the sensor is so thick that this is usually impossible without modifying your window or frame.

I came up with a simple case/pusher design that converts the "invisible" sensor back to a normal, visible sensor, easy to mount on any door or window. It consists in a case to install above the door/window, and a pusher to be fixed on top of the door/window. The sensor can be installed using nano tape adhesive, which is easy to remove.

I used the following components to make this project:

• EnOcean Battery-free Invisible Opening Sensor (product info, EU seller)
• Nano tape, 20mm width, 1mm thick (amazon, aliexpress)
• Some PLA (preferably white)
• ... that's it!

For those unfamiliar with EnOcean, you need an EnOcean USB dongle to integrate the sensors with your home automation system, e.g. using Home Assistant EnOcean integration. There's one frequency band per continent, so choose the appropriate dongle and sensor variant depending on your location. Second hand dongles are cheaper.

Build/Install instructions:

• Make sure to pair the sensor with your home automation system before installing
• Verify/Adjust pusher dimensions for your door/window by editing the CAD model
• Print case and pusher vertically with supports for best strength (see images)
• Print lid flat without supports, with height range modifier (see images)
• Insert sensor into the case, make sure the spring moves freely then add the lid
• Test sensor and pusher without adhesive to make sure the pusher does its job correctly
  • Note that putting nano tape will add 1mm offset between case/wall and window/pusher
• Install nano tape on the back of case and under the top of pusher (see images)
• Clean the surface to install, optionally heat it a bit with hair drier for best adhesion
• Install sensor and pusher, hold them firmly for about 10 seconds
• ... profit! You'll never ever need to change a battery