Meaning
Four-wire measurement circuitry isolates the voltage drop across a sample from the resistance of the test leads and contacts. Implementing contact resistance cancellation is necessary when measuring sub-milliohm values in battery current collectors. This method directs a known current through one pair of terminals while measuring voltage across a separate pair.
Electrical Circuitry
Two dedicated wires carry the test current, while two high-impedance sensing wires measure the voltage directly at the sample. Because almost no current flows through the sensing path, lead resistance does not affect the calculation. This configuration provides accurate results regardless of connector condition.
Sourcing Benefit
Quality control systems utilizing this approach reject fewer acceptable cells because of bad fixture contacts. Contact resistance cancellation increases the reliability of automated sorting benches by removing variability caused by mechanical wear. Purchasing agents select testers with this capability to avoid purchasing overly expensive gold-plated connectors.
Production Impact
High-speed assembly lines experience vibrations and dust that degrade the quality of electrical connections during testing. Automated systems that lack this compensation feature produce erratic impedance data that disrupts the sorting process. Incorporating the technology ensures that the cell sorting process remains stable and throughput targets are met.
Consistent testing reduces labor costs and enhances the competitiveness of the factory.
