Introduction
When deploying Raspberry Pi cameras for long-term, unattended field applications, power management becomes a critical consideration. These devices can consume significant power, especially when coupled with additional modules and wireless communication. This blog post will explore the challenges of powering Raspberry Pi cameras in field conditions and present a solution for optimizing power consumption and enabling continuous operation.
Power Consumption Challenges
Raspberry Pi 3 models, even at low CPU speeds, draw a substantial amount of current. Connecting additional modules and establishing wireless communication can further increase power consumption. Preliminary measurements revealed that a typical field imager, based on a Raspberry Pi, could draw over 500 mA of current. This level of consumption quickly depletes a 7000-mAh acid battery, even with an efficiency of 85%.
Power Management Solution
To address these power consumption challenges and ensure continuous operation, a custom power management panel was designed. This panel incorporates several key components:
Timer: A precise real-time clock (ChronoDot) provides accurate timekeeping for controlling the imager's on/off schedule.
Arduino Board: This microcontroller acts as the intermediary between the timer and the relay board, processing time data and sending control signals.
Relay Board: This device is responsible for physically turning the imager on and off based on the control signals from the Arduino.
Solar Panel: A 30 W solar panel helps recharge the batteries, extending the system's operational time.
Charge Controller: Regulates the charging process to prevent overcharging and ensure optimal battery performance.
Batteries: Two 7000-mAh lead acid batteries, connected in parallel, provide a reliable power source.
Enclosure: Protective housing for the entire system (custom-designed or off-the-shelf)
Necessary Cables and Connectors: For connecting components within the panel
Note: This is a basic BOM and may require adjustments based on specific requirements and component availability. Additional components may be needed depending on the exact configuration of your Raspberry Pi camera and the desired features of the power management panel.
System Operation
The power management panel operates as follows:
Timekeeping: The ultraprecise timer provides accurate time information to the Arduino.
Scheduling: The Arduino uses this time data to determine when to turn the imager on or off based on predefined schedules (e.g., 10:00 AM to 2:00 PM).
Relay Control: The Arduino sends control signals to the relay board, which then activates or deactivates the imager's power supply.
Solar Charging: The solar panel charges the batteries during daylight hours, extending the system's operational time.
Benefits of This Solution
Optimized Power Consumption: The system effectively manages power consumption by turning the imager off during non-productive hours.
Extended Battery Life: Solar charging and efficient power management help prolong battery life.
Reliable Operation: The use of a precise timer and a robust power supply ensures reliable operation in field conditions.
Customizability: The system can be easily customized to suit specific application requirements and scheduling needs.
Conclusion
By implementing this power management panel, you can significantly enhance the operational efficiency and longevity of your Raspberry Pi-based field imager. This solution ensures that the imager can capture images at the desired times while minimizing power consumption and maximizing battery life.
Reference
Osroosh, et al., 2018. Economical thermal-RGB imaging system for monitoring agricultural crops. Computers and Electronics in Agriculture, 147 (2018) 34–43.
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