How to judge the quality of 15000μF large capacitor with a multimeter
If the 15000μF large capacitor is good or bad, if you use the multimeter resistance file to judge whether it is good or bad by charging and discharging, this method is not feasible, because the test current of the multimeter resistance file is generally very small (μA level), measuring such a large capacitance, charging and discharging long time. If you want to judge whether the 15000μF capacitor is good or bad, the simple way is to use the diode or capacitance file of the digital multimeter to judge. The two methods are described below.
1. Use the capacitance file of the digital multimeter to directly measure the capacity
Measure the capacitance directly with the capacitance file of the digital multimeter. Many current digital multimeters can measure capacitance below 20mF (the "mF" here is read as "millifarad", 1mF=1000μF) (the previous multimeter can only measure the capacitance of 200μF at most), so to judge whether the 15000μF capacitor is good or not, You can directly measure its capacity with the capacitance file of the multimeter.
Use a digital multimeter to measure the capacitance of a 4700μF (since there is no 15000μF capacitor). The reading shown in the figure is 4.502mF, that is, 4502μF. Due to the large error of the electrolytic capacitor, the displayed capacity is normal. When measuring a large-capacity electrolytic capacitor, if the range is not exceeded, the displayed reading is always "1", indicating that the capacitor has a large leakage or has been broken down. If the measured capacitance is much smaller than the nominal value, it means that the internal electrolyte of the capacitor is dry, and it is generally not suitable for use.
2. Use the diode file of the digital multimeter to judge whether it is good or bad
If there is no digital multimeter that can measure large-capacity capacitance, you can also use the diode file of an ordinary digital multimeter to simply judge whether the capacitance is good or bad. Since the test current of the diode file is relatively large (mostly more than 1mA), the diode file measurement can quickly measure whether the large capacitor is broken down or damaged. When measuring, touch the two pins of the capacitor with a multimeter pen. If it is a good capacitor, the reading displayed on the diode file may be "0.000" in the first ten seconds, and then the displayed reading will gradually increase until it is displayed as " 1". If the reading displayed by the multimeter is 0.000 (or the reading is always small) for a long time during measurement, it means that the capacitor is damaged.
