A-H Measurement - Tektronix Keithley 2281 Series Reference Manual

Section 3: Functions and features Model 2281S-20-6 DC Power Supply and Battery Simulator Reference Manual

A-H measurement

The 2281S can measure the battery capacity (A-H) only when it is in the battery test function.
The instrument discharges the battery completely and then charges it completely; the charging
capacity in represents the total battery capacity.
Introduction to the A-H measurement
With its 6½-digit multimeter, the 2281S can sample the charging current continuously at a high
frequency during the battery test, as shown in the following figure.
Figure 104: 2281S sampling charging current
The capacity is computed integrally by A-H = ∑ I(n) * ∆t, where ∆t is determined by the sampling
interval.
Measurement process:
1. Connect 2281S to the battery.
2. Fully discharge the battery.
3. Set the target voltage V-Full, which is customarily 5% higher than the fully charged battery
voltage.
4. Set the End condition, which is the end current that stops the charging.
5. Set the sampling interval.
6. The instrument computes the battery capacity during the measurement.
7. You can also generate a battery model.
3-66 077114601 / March 2019