Pack build and assembly. Sort and match cells, spot weld and solder interconnects, build and dress harnesses, install BMS boards and sensing leads, pot and insulate, and close out the mechanical assembly. Work to the drawing, the BOM, and the revision that is actually released.
Prototype and first-article work. Sit with the engineering team on new designs. Build the first one, then tell us what was wrong with it. Fixtures, tooling, and assembly sequence are often undefined at this stage, and your input on what is actually buildable is a large part of the value you bring.
Test and verification. Run capacity, impedance, and cycle checks. Set up and operate cyclers and data acquisition. Record results cleanly enough that an engineer can use them a year from now.
Documentation. Turn what you did into work instructions other people can follow. Redline drawings that do not match reality. Keep serialization and traceability records accurate.
Safety and housekeeping. Lithium cells are unforgiving. You will own the safe handling, storage, and disposal practices at your bench and hold others to them.
Support the rest of the shop. Cable and harness work, box builds, and general electromechanical assembly come through here too. Some weeks the battery queue is light and something else is on fire.