How to measure the quality of a battery with a multimeter?
First, select an appropriate load resistor, and then connect the load resistor in parallel between the positive and negative poles of the battery. As shown in the following figure:
There is a known relationship between the battery voltage and the remaining power. Therefore, based on the battery capacity and its application, measure the voltage across the resistor. By observing the degree of voltage drop of the battery when it is under load compared to when it is unloaded, the remaining power of the battery can be judged.
However, the precondition is that no load is applied. Because when a load is added, the battery voltage will be distorted by the voltage drop caused by the internal impedance. The voltage will gradually decrease at different rates over time, and it will gradually rise after the load is removed. Therefore, if a load is applied, it will affect the test result of the dry battery's power.
A multimeter can also accurately measure the voltage of a dry battery. The power of the battery can be judged by measuring the voltage level of the dry battery. There are alkaline batteries and carbon batteries among dry batteries.
If the measured voltage is not less than the marked voltage of the dry battery, it indicates that the power of the dry battery is sufficient. The more the measured voltage is less than the marked voltage of the dry battery, the more the dry battery is discharged.
Due to different models, the test results of dry batteries may be affected. But for a single dry battery, when using an ordinary pointer multimeter, select the maximum current range (0.5A - 1A) of the multimeter. Connect the negative test lead to the negative pole of the battery, and quickly touch the positive test lead to the positive pole of the battery. At this time, pay attention to observing the movement of the meter pointer (short-circuit current) to know how much power is left in the battery.
For two identical batteries at home, if the open-circuit terminal voltage measured for each is 1.5V, the power of the batteries can be detected by measuring the internal resistance of the batteries. First, measure the open-circuit voltage of the battery, and then connect a load (such as a small light bead) to the battery. The voltage of the battery will drop, and then measure the voltage. Divide the difference between the open-circuit voltage and the voltage under load by the current during loaded operation, and the internal resistance of the battery can be roughly calculated. The greater the internal resistance of the battery, the smaller its power.
