Case for a moisture sensor and a 18650 battery.

I made 2 pieces. Both have been working outside for three weeks without any problems.

I used the ESP32-C3 module because it is small and has no additional elements that consume batteries.

The battery discharges about 450-500mAh/week, so a 2000mAh cell should work for about a month.

Non printable things ;)

• epoxy glue (to mount moisture sensor)
• nickel tape (to make battery connectors)

Connection:

Battery + to ESP32 3.3
Battery - to ESP32 GND
Moisture sensor GND to ESP32 GND
Moisture sensor VCC to ESP32 GPIO10 (this is important when battery powered, the sensor is not powered in deepsleep)
Moisture sensor SIGN to ESP32 ADC (I used GPIO3)

To measure voltage I use an external voltage divider (I had problems with the internal one and strange measurement values). Connect e.g. Resistor 2k2 connected to ground and GPIO2 Resistor 10k connected to VCC and GPIO2. You need to calibrate the sensor battery voltage value.

Humidity sensor works properly when the supply voltage is 3.3-5V. Below this value it starts showing incorrect measurements. (Humidity starts to increase slowly which is not true). Since the sensor is powered from GPIO10 I suggest replacing the batteries at a voltage of about 3.5V (on GPIO it is about 3.35V).

Printing:

Only battery case need support.

Have a nice fun.