Method for testing the quality of 25V 6800 microfarad capacitors

You can use a multimeter to measure it. For a digital meter, you can use the special capacitance range to measure it. You can also use the resistance range of a pointer meter to measure it.

It is relatively simple to measure with a digital meter, and the reading can be directly measured. Since most meters cannot measure capacitance above 200μF, the measurement can be carried out in series, and then the capacity of the measured capacitor can be estimated by counting.

Below is the result of my actual measurement using a 150μF capacitor. To reduce the error, I first measured the actual capacity of this capacitor, and the measured value was only 131.2μF. Then I connected it in series with a 6800μF capacitor. The total capacity measured is Ctotal:

The calculated result is consistent with the calculated result, which shows that the capacitor is good and the capacity is not a problem.

In fact, the capacitance range of the multimeter is not very accurate, so if the values ​​are not much different, the capacitance can be considered good.

Alternatively, you can use the resistance range of a pointer multimeter to measure. Since the capacitance of this capacitor is relatively large, you should use the low resistance range of Rx1 or Rx10 to measure it. For example, when using the Rx1 range of the MF47 meter, the pointer will move to about 60Ω when the probe touches the capacitor pin.

If the swing amplitude is too small, it means that the capacity is insufficient. If there is no swing or the pointer cannot return to zero after a large deflection, the capacitor is damaged. Regarding the swing amplitude, different multimeters will have differences, but the difference will not be too large.

After measuring the capacity, you can switch the gear to Rx1K or Rx10K to detect leakage. At this time, the pointer should gradually return to zero. If it always displays a resistance value below several hundred KΩ, it means that the capacitor has serious leakage and cannot be used anymore. When measuring with a pointer meter, pay attention to the polarity of the capacitor. The red test pen must be connected to the negative pole of the capacitor, otherwise there will be leakage.

In addition, the capacitor must be discharged before testing. Failure to do so may burn the multimeter or cause electric shock.