Meaning
Mechanical pressure applied at the junction of a test probe and a battery terminal ensures electrical continuity. Contact force determines the effective surface area available for current flow during charging or discharging cycles. It must overcome surface contaminants and oxide layers to establish a stable path.
Impedance Reduction
Lower electrical resistance results from the compression of microscopic surface peaks on the mating materials. When contact force is insufficient, the interface exhibits high impedance and generates excessive heat during high current testing. This stability is required for accurate internal resistance measurements.
Engineers specify a minimum threshold to ensure the contact remains viable throughout the entire test duration even if the cell shifts slightly.
Mechanical Stress
Excess pressure leads to the permanent deformation of the battery terminal or the probe tip itself. While high contact force improves electrical performance, it also accelerates the wear of expensive test equipment and potentially compromises the seal of the battery cell. Balancing these factors is a primary goal of fixture design.
Production Setting
Automatic testing equipment uses calibrated springs or pneumatic actuators to maintain a precise load. A typical contact force value for small cylindrical cells ranges from five to fifteen newtons.
