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introduction
To design a test system that meets your requirements for accuracy and bAttery teStinG
precision, you need to select appropriate instruments, apply creativity in batteries are used in a rapidly expanding variety of consumer and industrial
designing test methods, and pay careful attention to specifications and error applications. Their testing requirements typically depend on their chemistry,
terms. Most test system applications are complex enough that it is in the size, specific use, and whether the cells are primary or secondary.
designer's best interest to minimize the number of uncontrolled variables. To
accomplish this, the system switch performance should be tightly specified. Secondary (rechargeable) batteries are commonly tested using discharge and
charge cycling. The discharge characteristics of a secondary battery provide
Special consideration should be given to tests that approach the specified important information about the battery's capacity and life. Charging/discharging
limits of accuracy, resolution, or sensitivity of the measurement or sourcing a battery often takes several hours, so it is usually desirable to connect several
instruments. These generally represent the "most critical test requirements," batteries in series in order to charge and discharge them simultaneously. The
and switching should be selected to support these tests. An application voltage of each battery can be monitored during charging and discharging using
designed to perform against the "most critical test requirements" will usually a two-pole scanner.
satisfy other test requirements as well.
In some applications, it may be desirable to measure each cell voltage, both with
The applications outlined in this e-handbook offer a good overview of many and without a load. Monitoring the voltage decay over time will give an indication
of the types of test automation challenges you may face. of cell quality. While this is particularly true for primary cells, this technique can
also be used for secondary cells. Using a scanner makes it possible to monitor
the voltage decay of several cells at one time.
Model 2700/ 7702
Multimeter/Data Acquisition System The following paragraphs describe the switch configurations for both the charge/
discharge cycling test and the voltage monitoring test.
Charging
Ch. 1 1.2V Switching Configurations
10mA Figure 1 illustrates the switch configuration for charging/discharging a string
of cells connected in series. In this configuration, a series string of 40 cells is
Discharging connected to a current source (Model 2400 SourceMeter