This study investigates the complex determinants of electric vehicle (EV) charging performance through controlled experimental testing of multiple battery-charger configurations (5-30kWh batteries with 22kW, 30kW, and 50kW chargers). The research addresses the critical knowledge gap regarding how charging time and efficiency are influenced by the interplay between charging power, operating voltage, and battery capacity. Our findings reveal that upgrading from 30kW to 50kW charging infrastructure reduces charging time by 57.2% for 20kWh batteries. Statistical analysis establishes a strong negative correlation (r = -0.758) between power-to-battery ratio and charging time, identifying this as a critical optimization parameter. We document bidirectional voltage-charging time correlations ranging from -0.866 to +0.923 across different configurations, challenging the conventional assumption of uniform voltage effects. The coefficient of variation in charging times ranges from 9.4% to 27.2%, demonstrating the need for multiparameter standardization. Data was collected through standardized charging sessions in a controlled environment, with each configuration tested multiple times where possible. This original research is part of a comprehensive research project evaluating charging infrastructure performance for real-world deployment. The findings have significant implications for charging infrastructure planning, technical standards development, and consumer experience optimization, with the power-to-battery ratio emerging as a more useful metric than absolute charger capacity for predicting charging performance.