Design and experiment of drip irrigation control device with low-power solar energy

A drip irrigation control device powered by Low Power Consumption solar energy was developed for automatic applications in remote mountainous citrus orchards. The device consists of STM8S105S6 microcontroller, real-time-calendar module, pulse solenoid valve, valve driving circuit, sensor connector，solar energy charging sub-system, and a LCD's customizable user interface. In this paper, the output characteristics of lithium battery, phosphoric acid iron battery, photovoltaic panel and quiescent current of the controller in 2.8-4.3 V battery voltage were measured. Our experiment results indicated that the maximum output power of the photovoltaic cell was 169 mW, the lowest voltage required was 3.0 V, and the minimum quiescent current was 70 μA. It's estimated that a 3.7 V lithium battery with the capacity of 834mAh could support the device for more than 150 days without the solar power supply, and a solar charging at 42.25 mW for 30 minutes a day could support the system with non-interrupt running. This device is suitable for the automatic drip irrigation in suburban orchards with low power consumption, equipped with solar power charging, and with lightening protectors and waterproof case.