DESIGN AND DEVELOPMENT OF A SOLAR-RECHARGEABLE COB LED LAMP WITH LITHIUM-ION BATTERY CHARGE CONTROLLER FOR OFF-GRID RURAL COMMUNITIES IN NIGERIA

Reliable, affordable lighting is still out of reach for a large share of Nigeria's rural population, most of whom rely on kerosene lanterns, candles, and small petrol or diesel generators for lighting and device charging.These sources are costly to run, emit harmful pollutants, and pose fire and health hazards.This paper presents the design, construction, and performance evaluation of an affordable solar-rechargeable Chip-on-Board (COB) LED lamp built around a lithium iron phosphate (LiFePO₄) battery pack and a dedicated solar charge controller.The system integrates a 12 W monocrystalline photovoltaic panel, a 12 V/7 A pulse-width-modulated (PWM) charge controller, a 12 V/7.2Ah LiFePO₄ battery pack, a constant-current buck regulator driving a 5 W COB LED, and a 5 V USB port for charging mobile phones.The design methodology, load and component sizing calculations, circuit schematic, and system block diagram are presented, followed by charging, discharge, and illumination tests carried out under natural outdoor sunlight.Results show that the solar panel produced an open-circuit output of between 18.3 V and 19.3 V under full sunlight, the battery reached a full-charge terminal voltage of approximately 14.2 V after about six hours of charging, and continuous lamp operation provided an average backup time of approximately 10 hours before the low-voltage-disconnect threshold of 10.8 V was reached.Illuminance measured 169.6 lux at a distance of one foot from the lamp, adequate for reading and household activities.The prototype demonstrates that a low-cost, solar-powered COB LED lantern can offer a safer, cleaner, and more sustainable lighting alternative to kerosene-based sources for off-grid rural households in Nigeria.