What is battery spot welding? Battery spot welding is a key process in the cylindrical cell battery pack assembly process, which usually refers to the use of resistance welding technology to weld the cell-to-cell busbar onto the cylindrical cells. It is very common to spot weld nickel-plated steel strips or pure nickel strips onto the poles of cylindrical cells such as 18650, 21700, 26650, 26700, 32650 and 32700.

The battery spot welder presses the battery tabs onto the cylindrical cell pole through two battery spot welding electrodes, and then passes welding current through the contact surface of the battery tabs and the pole to generate resistance heat, heating the battery tabs to a molten state to achieve welding.

Figure 1. Semi-automatic Battery Spot Welder

Since the principle of battery spot welding is to use the principle of resistance heat to achieve the purpose of welding, it is necessary to follow Joule's law:

Q=I²RT

Where Q is heat (J), I is welding current (A), R is the resistance between two spot welding electrodes (Ω), and T is welding time (s).

From this, the material of the battery spot welding electrode is usually alumina copper, and its melting point and conductivity are very close to those of copper, but its resistance is higher than that of copper. When we use a battery spot welder to spot weld the copper busbar, the electrode and the busbar are in a molten state and will stick together. This is why it is not feasible to spot weld the copper battery tabs onto the cylindrical cell with a battery spot welder.

In addition, we can see that the welding current (I) has the greatest impact on the welding effect. When selecting a battery spot welder, it is necessary to consider the welding current range that it can output.

WinAck Group can provide complete battery spot welding solutions. Come by, contact us for a solution that can help you succeed. For better batteries, Win & Ack!