How to use a multimeter to measure the current of a charging current device
For a pointer multimeter, its red probe needs to be connected to the positive terminal of the charger output, and its black probe needs to be connected to the charged electrical load. If a digital multimeter is used to measure the current in a charging circuit, its red and black probes can measure the value of AC or DC current in the circuit even if they are reversed, except that there is a - (- negative sign) in front of the display on the digital multimeter.
For measuring relatively small AC or DC charging currents, the current level of the multimeter can be set to 500mA. If measuring a charging current exceeding 500mA, it is necessary to set the pointer multimeter or digital multimeter to the 5A position of the pointer multimeter (except for a few models that have a 10A position, the MF47 multimeter usually only has a 5A DC current position), while the digital multimeter has an AC or DC current position of 10A or 20A.
Because the digital multimeter I usually use has automatic gear shifting, I can only use it. Other digital multimeters only require shifting the gear to point to 20A. At this point, insert the red probe into the 10th gear, and if the black probe is still missing in the original COM socket, it is sufficient.
I don't know if the charger mentioned by the questioner is a mobile phone charger or an electric scooter charger. However, no matter what charger it is, in order to measure the DC charging current in the circuit, it is necessary to disconnect one of the charging wires (or disconnect one of the charging wires at another location on the charging plug, and connect the red and black probes of the multimeter in series in the circuit). At this point, insert the input wire plug of the charger into a 220V power supply and observe the actual charging current between the charger and the charged load.
If it is a mobile phone charger, one charging wire needs to be discarded, and the two probes of the multimeter's DC current range need to be measured in the circuit.
Set the multimeter to the current mode and follow the principle of selecting high and then low modes, and connect it in series to the charger circuit that needs to be measured.
It should be noted that batteries generally use constant voltage charging method for fast charging. Due to the constant charging voltage, the charging current at both ends of the battery is relatively low, and the starting charging current will be large. As the voltage increases, the charging current at both ends of the battery will gradually decrease. Therefore, the charging current measured at different charging time periods is different.
