The charger can charge the battery with an almost constant current or dynamically change it as the capacity is increased. Connecting an ammeter in series with the battery, even with a very low internal resistance, can disrupt the charging mode. A special non-contact device will come to the rescue.
Instructions
Step 1
The device you need can be called differently: clamp meter, non-contact ammeter, current clamp, etc. All these names are synonymous. Choose a clamp meter in which the element that is sensitive to the magnetic field created by the current conductor is not an inductor, but a Hall sensor. It differs in the coil in that it reacts not only to an alternating, but also to a constant field, which means that the current clamp with it is able to measure direct current in a non-contact way.
Step 2
Use the limit switch on the instrument to select the range that best matches your intended charge current. Its approximate value is indicated in the instructions for the charger or directly on the case of the latter. Press the clamp meter lever and the magnetic core halves will disperse. Place one of the conductors that carry the charging current between them. Do not place both conductors at once, because then their fields will be mutually compensated, and the current clamp will show zero even with a significant current strength.
Step 3
Close the magnetic circuit and turn on the charger. You will immediately see the current value on the indicator. Start the stopwatch at the same time. Enter the readings of both devices in the table. Divide the duration of the charge cycle indicated in the instructions for the charger into several intervals, and it is with this frequency that you continue to record the readings of both devices in the table.
Step 4
When the charge is complete, turn off all devices, including the charger itself, disconnect the battery, and then plot a graph of the charge current versus time. Select the horizontal coordinate for time and vertical for current. If you now show this graph to a specialist, he will be able to say a lot both about the literacy of the charge algorithm chosen by the designers of the device, and about the state of the battery itself. Perhaps the latter needs to be replaced or restored with the help of special equipment.
