5
Programming Overview
A Cell Forming Overview
The cell forming process of the Agilent E4370A MCCD consists of a series of steps or actions that are performed on a group of cells until the process is complete. This cell forming process is here referred to as a sequence, the essence of which consists of three steps: charging the cell, resting the cell, and discharging the cell. These steps may be repeated a number of times and in any order within the sequence, depending on your process. The transition from one step to the next is controlled by tests within the step that specify measurement criteria that must be satisfied. You can specify at what time during the test that the measurement will be made and what action to take if the measurement criteria is met. Two additional steps, ac resistance and dc resistance, are available that are used to measure the ac or dc resistance of a cell. These measurements cannot be made while the cell is charging or discharging.
Steps define the voltage and current stimulus that is supplied to the cell and the length of time that a stimulus is applied. Tests within the step measure the cell, define measurement limits, compare the measurement to the limits, and specify an action to take based on the outcome of the comparison. Refer to the cfSetSeqTest function in this chapter 6 for a list of all of the tests that can be performed in a given step. Note that the ac resistance and dc resistance tests can only be performed within their respective ac resistance and dc resistance steps.
Cells may be tested before or after a specified time in the step or they may be tested once at a specific time. Cells may also be tested at the beginning of a step, before a stimulus is applied, to ensure that it is safe to charge or discharge the cell.
Depending on the outcome of a test, a cell can either bypass the remaining tests and go to the next step in the sequence, or get flagged as failed and removed from the sequence. This is illustrated in figure
NOTE: There are no sequence restrictions on individual cells. What this means is that a cell can be at any point in a cell forming sequence independent of any other cell. Cells can charge, discharge, or rest at the ratings specified for the specific step that they are in. AC and DC resistance measurements are also performed on individual cells whenever they enter an ACR or DCR step. Outputs to the cells can also be turned on or off individually.
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