1. Core Definitions and Differences in Battery String Count (Most Fundamental Difference) • 54.75V: This is the full-charge voltage of a 15-cell lithium iron phosphate battery pack, calculated from the full-charge voltage of a single lithium iron phosphate cell (3.65V × 15 = 54.75V), corresponding to a nominal battery pack voltage of approximately 48V (3.2V × 15). • 58.4V: This is the full-charge voltage of a 16-cell lithium iron phosphate battery pack, calculated similarly as 3.65V × 16 = 58.4V, corresponding to a nominal battery pack voltage of approximately 51.2V (3.2V × 16).   2. Differences in Charging Compatibility and Safety Characteristics • 54.75V: Requires a charger compatible with 15-cell lithium iron phosphate batteries. The charging mode must match the three-stage charging of lithium batteries (constant...