Meaning
Chemical reaction between a metallic terminal and oxygen in the atmosphere that forms a non-conductive or semi-conductive surface layer. Untreated contact oxidation increases the electrical resistance of the path between the battery cell and the test equipment. Silver or gold plating is frequently used to slow the growth of these insulating films.
Surface Film
Atmospheric moisture and heat accelerate the development of metal oxides that act as a barrier to electron flow. This film often requires a minimum wetting voltage to break through the insulation and establish a circuit. Unreliable measurements result when the film thickness varies between test points because the resistance is no longer a constant value.
The erratic nature of the connection makes high precision monitoring impossible.
Thermal Impact
Elevated temperatures during high power cycling drive the oxidation process deeper into the base metal. Resistance rising at the contact point creates a feedback loop where more heat is generated by the current. Excessive heat can damage the terminal or the cell casing.
Cleaning Protocol
Mechanical abrasion or chemical treatments remove the accumulated oxide to restore the original conductivity. Automated systems sometimes include a wiping motion to clear the surface during each connection cycle. Periodic maintenance preserves the integrity of the data.
