Spotmeister — Automatic Spot Welder

01Requirements

Consistent, repeatable spot welds on battery cell tabs — weld quality directly affects pack safety and resistance
Programmable weld sequences so different cell/tab combinations can be stored as recipes
Operator-safe enclosure with clear controls: power, regulation, fault indication, weld output
Serviceable construction — sheet-metal enclosure with accessible internals for maintenance

02Key Decisions

Buy a commercial welder or build?

Build. Commercial battery spot welders at the required capability were costly, and in-house build meant the weld sequencing could be tailored exactly to the pack production process — and modified as cell formats changed.

Controls architecture?

Custom HMI with programmable sequences. An industrial control screen exposes weld programs to the operator, with parameters stored per recipe — drawing on the same embedded HMI experience used on the dynamometer (LinuxCNC/Raspberry Pi custom interfaces).

03Process

Frame and enclosure designed in sheet metal with DFM for laser cutting and bending; front panel laid out for operator flow — power, regulator, start/stop, fault light, weld output terminals. Power and control wiring built as a proper harness. Weld sequence programming, then commissioning against real battery tabs with weld quality checks.

Machine design

Control unit — built

Programmable HMI

04Challenges

Weld consistency across tab variations

Cell tabs vary in material and thickness; one fixed weld setting produces cold welds on one tab and blow-through on another. Programmable per-recipe sequences solved this — each cell/tab combination gets stored, tuned parameters.

High-current and control electronics in one box

Weld current pulses and sensitive control electronics share an enclosure. Wiring layout, separation and grounding discipline kept the controls stable during weld pulses.

05Outcome

Delivered

Working production machine used for battery tab welding — complete in-house build from sheet metal to weld program.

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