Implementation of a Battery Management System for Lithium-Ion Battery Packs Used in Electric Tricycles in Abuja

This project implements a battery management system for lithium-ion battery packs intended for use in electric tricycles (Keke Napep) in Abuja, Federal Capital Territory, supporting the gradual transition from petrol-fuelled to electric urban transport. Lithium-ion batteries offer high energy density and long cycle life but require precise monitoring and protection to prevent overcharging, deep discharge, and thermal runaway, which can cause fires and premature capacity degradation. The designed battery management system employs a Texas Instruments BQ76940 battery monitor integrated circuit to measure individual cell voltages, pack current, and temperature across a 24V, 40Ah, six-series battery configuration. An STM32 microcontroller processes the measurement data and implements cell balancing, state-of-charge estimation using a Coulomb counting algorithm corrected by open-circuit voltage lookup, and protection cut-off logic. Active alerts are communicated to the rider through a dashboard indicator and an audible buzzer. A passive cell balancing circuit dissipates excess energy from overcharged cells to maintain pack uniformity. The prototype was integrated into a modified commercial Keke Napep chassis and road-tested over 200km in and around Abuja. State-of-charge estimation accuracy was within 4 percent of laboratory-measured capacity. Cell voltage deviation within the pack was maintained below 30mV throughout cycling. Thermal measurements confirmed safe operating temperatures under typical Abuja ambient conditions. The project recommends scaling the design to a 48V architecture for improved motor efficiency on longer routes. Keywords: battery management system, lithium-ion, electric tricycle, state of charge, Abuja.