How to use a multimeter to measure the quality of the battery
1. Firstly, select an appropriate load resistor, and then connect the load resistor in parallel between the positive and negative terminals of the battery. As shown in the following figure:
There is a known relationship between battery voltage and remaining capacity, so the voltage across the resistor can be measured based on the capacity and purpose of the battery. By observing the degree of voltage drop when the battery is loaded compared to when it is unloaded, the battery's capacity can be determined.
However, the premise is that no load is applied, because after adding a load, the battery voltage will cause voltage drop distortion due to internal impedance, gradually decreasing at different rates over time, and gradually increasing after removing the load. Therefore, if a load is applied, it will affect the detection results of the dry battery power.
2. A multimeter can also accurately measure the voltage of a dry battery. The power level can be determined by measuring the voltage of the dry battery. Dry batteries include alkaline batteries and carbon batteries.
If the measured voltage is not less than the marked voltage of the dry battery, it indicates that the battery is fully charged; The more labeled voltages below the dry battery, the more depleted the dry battery is.
Due to different models, the detection results of dry batteries may be affected. However, for a single dry battery, as long as a regular pointer type multimeter is used, select the maximum current range (0.5A-1A) of the multimeter, connect the negative probe to the negative terminal of the battery, and quickly touch the positive probe on the positive terminal of the battery. At this time, pay attention to the movement of the probe (short-circuit current) to know how much battery power is left.
The open circuit voltage of two identical batteries at home is measured to be 1.5V, and the battery capacity can be detected by measuring the internal resistance of the batteries. Firstly, measure the open circuit voltage of the battery, and then connect a load (such as a small light bulb) to the battery. The voltage of the battery will decrease, so measure the voltage. The difference between the open circuit voltage and the load voltage divided by the current under load can roughly calculate the internal resistance of the battery. The larger the internal resistance, the lower the battery capacity.
Note: In general, it is difficult to accurately measure the quality of a battery using a multimeter unless the battery has zero voltage.
