How to extend solar and battery power in a weather station

Experiment 2

Aim
To run an MCU on low power mode, read the temperature, pressure, and humidity readings using AHT10 and BMP280 Sensors, and send the readings over wifi.

Requirements

MCU: ESP32-WROOM-32D (Generic Wi-Fi + Bluetooth + Bluetooth LE MCU module)
Temperature/Humidity Sensor: AHT10 (Temperature and humidity sensor)
Pressure and Altitude Sensor: BMP280(Absolute Barometric Pressure Sensor)
Battery: KP 903048 (3.7V, 1000mAh)

Theory
In this experiment, we are using MCU ESP32-WROOM-32D. The ESP32 will remain in active mode for 6 seconds, take the temperature and humidity reading and send it over wifi. It will stay in deepsleep() mode for 5 minutes. After that time, the ESP32 will be back in deep sleep mode.

Schematic

Fig: 1 Schematic of Weather Station

Experiment Setup
Below showing the image is the Setup of the Experiment:

Fig: 2 Experiment Setup

Code

Observation
Below is the image showing the results of the sleep and the active mode of the MCU. So, we can see that the sleep time is 5 minutes, and the active mode remains for ~6 seconds. In six seconds, the whole device takes a current of about 120mA.

Fig: 3 Active v/s sleep mode of MCU

In sleep mode, the device takes 10-150 uA of current.

Below are the images showing the device’s current consumption from sleep mode to active mode. It reaches ~122mA of current in active mode.

Fig: 4, 5 Current Consumption in sleep mode

Fig: 6, 7 Current Consumption in active mode

Now battery capacity is 1000mAh. Solar will charge the battery whenever the battery goes low, and this device will run for a long time.

Current consumption when the solar charges the battery is shown below.

Fig: 9 Current Consumption in while solar charging battery

The current consumption while charging the battery is about 47mA.

Battery life: If we don’t use solar to charge the battery, the battery life will be about 16 days.

Results

Below are the results of the data which the device sent to the ThinkSpeak platform

When the device is away from the sun, it means there is no charging by solar.

Fig: 10 Readings of pressure from BMP280 sensor

Fig: 11 Readings of Temperature from AHT10 sensor

The temperature remained below 31 degrees celsius as the device was placed inside the building.

Fig: 12 Readings of Humidity from AHT10 sensor

Fig: 13 Readings of Current from INA219 sensor

Battery power consumption is shown, which is between 450-500 mW.

Fig: 14 Readings of Current from INA219 sensor

Solar power is zero as the device was inside the building, and no charging is done.

When solar charges the battery:

Fig: 15 Readings of pressure from BMP280 sensor

Fig: 16 Readings of Temperature from AHT10 sensor

The temperature rose above 50 degrees celsius as the device was placed outside the building.

Fig: 17 Readings of Humidity from AHT10 sensor

Fig: 18 Readings of Current from INA219 sensor

Fig: 19 Readings of Current from INA219 sensor

When aolar charges the battery, the power consumption is shown in the above analysis.

So, This was the experiment in which the MCU’s deep sleep mode was performed. The data and the results show that deep sleep mode helps reduce power consumption.