Read the specification boundary
A Wh/kg figure describes the cell under stated test conditions. It does not include the enclosure, BMS, wiring, structural supports or thermal provisions needed in a finished pack.
Account for the system
Compare complete pack mass, operating voltage, usable energy, continuous and peak power, temperature range and protection requirements. Keep test conditions and acceptance criteria consistent across options.
Validate in the application
The right cell depends on the system constraints and the validated design. Use product figures for initial screening, then review the controlled datasheet and prototype data with the engineering team.