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Caution:
5000 chassis to earth ground. Autoclaves, stress apparatus, and field measurements may involve earth-
grounded electrodes. A binding post on the rear panel of the Interface 5000 is provided for this purpose. A
water pipe can be a suitable earth ground.
Warning:
of earth ground. Consult a qualified electrician if you are uncertain how to obtain an earth ground.
Connecting the Interface 5000 to an incorrect and unsafe voltage can create a safety hazard (see Chapter 1
for details).
If you are measuring very small currents, you may find that a metal enclosure completely surrounding your cell
(a "Faraday shield") significantly lowers measured current noise. You should normally connect this Faraday
shield to both earth ground and floating ground. The floating ground on the black cell lead is a convenient
source of ground.
If any electrode in your cell is connected to earth ground, only connect your Faraday shield to the black cell
lead (Floating Ground).
You can remove the alligator clip on any cell connection to gain access to the underlying banana plug or pin
jack. Gamry Instruments also can provide additional standard or special cell cables.
Three-Electrode Battery Connections
Many battery tests are done in using a three-electrode cell. In some cases, the tests are traditional half-cell tests
in which the electrochemical behavior of only a battery anode or cathode are of interest. In these cases, the
behavior of the counter electrode is unimportant, and the Normal-Cell connections described above are used
with the electrode of interest connected to the Interface 5000's Working electrode terminal. In the
Electrochemical Energy software, these tests are run in half-cell mode. Note that Gamry's three-electrode
Lithium Battery Cell is a convenient tool for this type of testing.
In other three-electrode cell cases, the cell under test is a conventional battery with an embedded reference
electrode. The tester is usually interested in the electrochemical behavior of both the anode and cathode.
Examples of cells used in this way include specialized Swagelok
inserted in a coin cell or a spirally wound cell (such as an 18650). In Gamry's Electrochemical Energy software,
you run these tests in Stack mode.
Save Both Half Cells is a feature that allows you to monitor the both half-cell voltages when an embedded
reference electrode is used. Connect the working and working sense to one electrode, the reference lead to the
reference electrode, and the counter and counter sense to the second electrode. If you do not select this
feature, the potentiostat/galvanostat monitors the potential between the working sense and reference leads.
When you select Save Both Half-Cells in Gamry's PWR800 software, the software calculates the negative
electrode half-cell potential by subtracting the positive half-cell potential from the full-cell potential.
Cell Connections
If any electrode in your cell is at earth ground, never connect the Interface
Make sure that your earth-ground connection is made to a legitimate source
39
-like cells and cells with a reference electrode
®
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