Heavy-duty flashlights, portable medical devices, and custom robotics build packs out of 21700 cells for extended runtime. 7. Battery Management System (BMS) Design Requirements

Panasonic is very clear on this: The NCR21700T is designed for spot-welded nickel strips. Soldering irons transfer too much heat into the cell, melting the internal separator and causing an internal short. If you see a loose NCR21700T with solder blobs on it, run away.