Appendix 3 Measurement values when using four-terminal measurement (Differences in mea-
A5
Appendix
Depending on the subject of measurement, such as a lead-acid battery, mea-
surement values may vary due to the measurement lead used. Since these dif-
ferences in measurement values are due to the shapes and dimensions of the
probes used in four-terminal measurement, measurement values taken using
any probe represent the true values for that probe only.
When judging battery wear using changes in resistance values with time, be
sure to use measurement leads having the same dimensions.
Explanation
Differences in measurement values are physical phenomena resulting from dif-
ferences in the distances (dimensions) between current-impression pins and
voltage-measurement pins. The greater the battery terminal resistance in com-
parison to the battery's internal resistance, the more marked these differences
become.
The following diagram shows how differences in voltage detected result from dif-
ferences in distance when measuring a lead-acid battery.
Appendix 3 Measurement values when using
four-terminal measurement
(Differences in measurement values
due to measurement leads used)
A
B
+Terminal +Terminal-Terminal -Terminal
Lead-acid battery Lead-acid battery
Equipotential lineEquipotential line
Potential gradient Potential gradient
V (voltage detected):
A
>
B
Parallel pins
Example: The model L2100/L2110
Pin distance： 2.5 ｍｍ
Coaxial pins
(Example: The model 9770)
Pin distance： 0.6 ｍｍ
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