Battery Test Equipment
Anyone doing EIS on coin cells or 18650s needs four-terminal measurements in order to eliminate additional impedances due to cable connections. The contacts on each holder have been gold plated to reduce contact impedance and cable connections have been designed to reduce inductive pickup between the current-carrying leads and the sensing leads. The cable connections also ensure a reproducible lead placement, reducing variability in your measurements.
The importance of four-terminal measurements cannot be understated. The Nyquist plot shown to the right highlights the significant benefits of four-terminal measurements over two-terminal measurements. You can see the increased resistances, seen as an increased x-axis offset and increased semi-circle diameter, and capacitance, seen as increased semi-circle height, associated with the two-terminal measurement.