RCWL-0516 + Battery Enclosure

thingiverse

**Home Security with an Affordable Microwave Radar Sensor** This project includes a 3D printed enclosure for the *RCWL-0516 Microwave Radar Sensor* and one 18650 3.2 volt LiFeP04 battery. The enclosure also has enough space for an ESP32 to provide communication via WiFi or BLE. **Basic Operation** When the sensor detects intrusion, it wakes up the ESP32 from deep sleep. The ESP32 then either analyzes the situation further or fires up the WiFi or BLE and sends the necessary data. Once done, it returns to deep sleep, greatly reducing current consumption. **Battery Choice** (Updated 27/02/2018) The ESP32 operates from 2.3v to 3.6v and appears to run reliably down to ~3.0 volts with the RCWL-0516 sensor. Charging the LiFEP04 to 3.6 volts should allow approximately 28 days of operation, during which time the battery discharges at 0.010 volts per day, increasing to 0.025 volts as the voltage nears the minimum 3.055 volt cutoff. **Testing:** 02/02/2018 - 28/02/2018 After some initial testing with a single LiFePO4 battery charged to 3.6 volts (to allow for connection to a 3.3 volt microcontroller), it appeared that 28 days was possible for a battery charged to 3.6 volt. If, however, we use a 5-volt tolerant microcontroller, we can charge the LiFePO4 to 4.2 volts (max safe charge), extending the period between charges. **Conclusion:** In real-world testing, I have determined that the minimum working voltage for reliable operation is approximately 3.1 volts. The sensor will continue to operate down to 3.0 volts or less, but the intruder must pass close to the detector for reliable detection. Basically, unless you're prepared to change/charge batteries every couple of weeks, it's best to power the devices from the mains using a small USB type power supply. The only option is to find a method to reduce the quiescent current even further, which normally requires a passive sensor such as a PIR or possibly a microphone.