Design and Development of a Solar Charger Using a Constant Boost Current Drive

The demand for portable electronics and the transition towards renewable sources of energy demand efficient solar energy harvesting technology. This project deals with the conceptualization, development, and demonstration of a solar charger for a battery using a constant boost current drive topology. The primary objective was the development of a highly effective charging system for a single-cell Lithium-Ion (3.7V, 2000mAh) from a low-voltage (6V) solar panel by solving the intrinsic problem of boosting the panel's dynamic output up to the charging voltage demanded by the battery.

The system includes a boost converter configuration, which provides a boost for the input voltage. A dedicated charge controller IC is utilized for the implementation of the proper Constant Current (CC) and Constant Voltage (CV) charging algorithm required for the health and well-being of the Li-Ion batteries. Further, a streamlined Maximum Power Point Tracking (MPPT) approach was also added for the maximum power harvesting from the solar panel for varying lighting conditions. The hardware prototype was designed carefully, with the major components like the power inductor and filter capacitors selected after stringent calculations for stability and efficiency.

The assembled charger was sufficiently validated under controlled conditions. Results also substantiated the potential of the circuit to maintain a steady charging current of 500mA constantly during the bulk charging mode and smoothly transfer to a steady voltage of 4.2V during the termination mode. The system achieved a maximum efficiency of up to 87%, thus vindicating the strategy of the design. The project conclusively demonstrates a feasible, efficient, and safe methodology for small-scale solar power harvesting, which provides a great starting point for portable and off-grid charging applications.