Fridge monitor
Temperature and humidity inside the fridge, door-open by tilt, on a rechargeable 18650 cell. From $58 in parts.
Parts
- ESP32-S3-DevKitC-1 (N8R8) C-001$19.95
- BME280 Temperature, Humidity and Pressure Sensor P-001$14.95
- MPU-6050 6-DoF Accelerometer and Gyroscope P-004$12.95
- 18650 Li-ion Battery, 2200 mAh E-001$9.95
- TP4056 Li-ion Charger Module E-004price pending
Parts from $57.80 (1 not priced yet) · powered by the 18650 Li-ion Battery, 2200 mAh
Wiring
The volts are the parts' own: the 18650 Li-ion Battery, 2200 mAh puts out 2.5–4.2 V, and the ESP32-S3-DevKitC-1 (N8R8)'s regulator makes the 3.251–3.349 V rail its GPIO and most of the sensors run from. Which header pin each lead lands on is our suggestion — the registry has no pin map, and nothing here has been wired on a bench.
Power the board off while you plug anything in. Every connector here is keyed: if it doesn't click in easily, turn it over rather than forcing it.
Readings
What this build sends: one column per channel its parts read or drive, with the unit the capability carries. The values and times below are sample data.
| Time | Air temp °CP-001 | Humidity %P-001 | Door tilt gP-004 |
|---|---|---|---|
| 3.6 | 61 | 0.02 | |
| 3.8 | 62 | 0.02 | |
| 4.1 | 63 | 0.02 | |
| 5.2 | 68 | 0.98 | |
| 4.4 | 65 | 0.11 | |
| 3.9 | 62 | 0.02 |