A crucial aspect of battery charging is the chargers ability to cease charging when the battery terminal voltage begins to decline (negative voltage slope). Overcharging a battery can lead to irreversible damage.

While testing a charger, it is possible to use an actual secondary battery as a reference. However, this approach can be time-consuming and impractical from both a time and cost perspective.

Alternatively, when employing an electronic load, ensure that it is set to the Constant Voltage (CV) mode and programmed to the desired terminal voltage. For example, to test the output current regulation of the battery charger for a 1.2V secondary battery, program the terminal voltage to step through values such as 1.0V, 1.2V, and 1.44V. Then, set it to 1.40V (indicating the battery is fully charged) to assess whether the battery charger correctly shuts down.