Pack design
Interconnect welding
Joining cells to busbars by resistance welding or laser welding rather than soldering, which is the accepted method for cylindrical cell assembly.
What it changes in practice
Soldering directly to a cell can puts heat into a sealed component that was not designed to receive it, and the joint is difficult to make repeatable at production volume. Resistance and laser welding make the joint in milliseconds with a controlled heat-affected zone. The weld is also an electrical component: a poor joint adds resistance that produces local heating, and it is one of the more common causes of a pack that tests well and fails in the field.
Why it matters when you specify a cell
Interconnects are where packs fail, not the cells. Resistance welding is standard and sensitive to electrode condition and pressure; laser welding is more consistent at volume; wire bonding doubles as per-cell fusing. Soldering to a cell can is not acceptable in production — the heat damages the seal, and the failure appears months later.
Related terms
Read further
More in Pack design
Other terms in this group
From single cell to assembled pack.
BMS (battery management system)
The electronics that monitor cell voltages, current and temperature and disconnect the pack when any of them leave the manufacturer window.
Read the entry →Cell balancing
Equalising the state of charge of cells connected in series, either by dissipating excess charge from the highest cells or by moving charge between them.
Read the entry →Series and parallel configuration
How cells are connected to reach the required voltage (series, written S) and capacity or current capability (parallel, written P).
Read the entry →