This study presents an experimental investigation of open- and closed-loop speed control applied to a 2.2 kW brushless DC (BLDC) motor integrated with a planetary gearbox and evaluated under variable-speed and fixed-load conditions. The aim is to characterize the dynamic response, energy-conversion efficiency, and battery state-of-charge (SOC) behavior of the powertrain under real-time control strategies. A complete laboratory platform was developed using a commercial BLDC motor controller, a 60 V–17.4 Ah lithium-ion battery pack, an optical speed sensor, and an eddy-current dynamometer capable of applying load torques from 1.5 to 7.5 N·m. Open-loop operation regulated speed through direct voltage modulation, whereas closed-loop control was implemented using a proportional–integral–derivative (PID) algorithm executed in real time on a microcontroller. Real-time measurements of voltage, current, torque, and speed were used to compute electrical power, mechanical power, and system efficiency, while battery SOC variation was estimated using the Coulomb-counting method. The results indicate that open-loop control exhibits substantial speed-tracking errors, pronounced transient power surges during speed transitions, reduced efficiency, and an increased SOC depletion rate over the investigated speed range of 1000–2600 rpm. In contrast, the closed-loop PID controller maintains steady-state speed errors within approximately 1 % across all load levels, suppresses current fluctuations, mitigates transient losses, and enhances overall system efficiency by approximately 14–19 percentage points. Closed-loop operation further reduces SOC depletion by 0.49–0.75 percentage points, depending on the applied load torque. These findings demonstrate the effectiveness of feedback control in improving stability, energy utilization, and electric powertrain performance in BLDC-based propulsion systems, with direct relevance to electric-vehicle and hybrid powertrain systems.