DESIGN AND CONSTRUCTION OF AUTOMATIC BATTERY CHARGER
Abstract
This project presents the design and implementation of an automatic battery charger capable of
efficiently charging 12V lead-acid batteries while providing overcharge protection through an
automatic cut-off mechanism. The charger utilizes a step-down transformer, rectifier circuit,
transistors, and a Zener diode-based voltage sensing system to initiate and terminate the charging
process without human intervention. The system was tested using a 15V AC input and a partially
discharged 12V battery. Results confirmed that the charger effectively detected low battery
voltage, activated charging via a relay, and automatically disconnected the battery once the
terminal voltage reached 13.8V. The auto cut-off function was both reliable and repeatable across
multiple test cycles. The project successfully met its design objectives, providing a safe,
convenient, and efficient solution for battery charging. Recommendations for future improvements
include adding heat sinks for thermal stability, a fuse for circuit protection, and a digital voltmeter
for real-time voltage monitoring. The charger proves suitable for practical applications requiring
automated battery management.
Full-Text Access Notice
In accordance with the NERD Policy on promoting peer-reviewed publication, public access to the full text of a project, thesis or dissertation is restricted for three years, allowing the author and supervisors sufficient time to pursue peer-reviewed publication.
During this period, researchers with legitimate academic or research purposes may request authorisation directly from the author to enable NERD to release the indexed full texts of the work using the form below.