Sustainable Electrification of Tricycles (Keke NAPEP) in Nigeria (Engineering Design, Conversion, and Field Evaluation of Electric Drivetrain Systems): A Field-Validated Conversion Architecture for Nigeria’s Urban Paratransit Fleet

Nigeria’s Keke NAPEP tricycle fleet has grown from 38,000 registered units in 2010 to an estimated six million by 2024, making it the dominant last-mile mobility mode in the country’s urban centres. The fuel subsidy removal of May 2023 drove petrol prices from ？185 per litre to ？1025 per litre by 2024 increasing the daily fuel expenditure of a typical operator from ？740 to over ？6150, representing 176% to 264% of Nigeria’s daily minimum wage equivalent of ？2333 (based on the ？70,000 monthly minimum wage enacted July 2024). At the fleet level, 1.6 million registered petrol tricycles consuming 4 to 6 litres per day collectively generate an estimated 6.75 to 8.09 million tonnes of CO₂ annually approximately 11.7% to 14% of Nigeria’s total transport sector CO₂ emissions of 57.9 million tonnes. This paper presents the design, physical conversion, iterative field testing, and performance evaluation of an electric drivetrain system for the Bajaj-type 200 cc Keke NAPEP the most common vehicle class across Nigeria’s tricycle fleet. Using a design-build-test methodology, the study conducts three tiers of field testing with four documented hardware iterations, measuring motor winding temperature, controller junction temperature, battery state of charge, vehicle range, and drivetrain performance under real Nigerian urban operating conditions. Key results establish, through measured field data, that a 3 to 5 kW Permanent Magnet Synchronous Motor matched to a minimum 72 A-rated controller with open forced-convective cooling eliminates thermal shutdown events that occur in passively mounted configurations: controller heatsink temperatures were reduced from a measured 78？C - 85？C (triggering protection events at 25 - 35 minutes) to 49？C - 58？C (no shutdown events) through the validated architecture. A 10:1 helical gear reduction ratio was found to maintain motor current below 75% of rated value on all tested gradients while achieving a maximum vehicle speed of approximately 55 km/h, compared to 90% rated current demand at the initial 8:1 ratio. A 96 V, 80 Ah lithium iron phosphate battery delivers a measured range of 80 - 95 km per charge cycle, satisfying the characterised daily operational requirement. At the validated conversion cost of ？800,000 to ？1,200,000, daily fuel savings of ？3000 to ？5000 produce a payback period of 6 to 12 months.