Features: MESR-100 V2 Auto-ranging capacitor ESR and Low Ohm Meter Measuring range from 0.001 to 100.0R, support IN CIRCUIT Testing. Using true 100 KHz sine wave to measure the ESR value, which is equal to the testing method of capacitor manufacturer. In the market, there is some technique using short pulse method to testing, but the value will be varying vs the capacitance and sometimes reading is different from the manufacturer's value.
What is ESR of capacitor? There is a series resistor inside capacitor, using 100kHz to remove the impedance 1/(2*pi*F*C), the impedance become small, and we can then measure the true series resistor value. A bad E-capacitor will have larger ESR and create large ripple rather than filtering noise. Normally, a big capacitor is larger than 3 ohm.
Specifications: 1) Accuracy: Up to 1% (detail on above table) Wide Measurement Range: >1uF (for 0.1uF the error will be larger on equation 1/(2*pi*F*C) @ 100Khz ) 2) High Resolution: 4 digit, or 0.001Ohm @ 1 Ohm range 3) Measuring voltage: <~40mV RMS (TESTING VOLTAGE) 4) Clamping voltage: ~0.15V (open voltage) 5) Battery 2X AA 1.5V battery 6) External Power: 5V micro USB 7) Operating current 0.02A 8) Battery Life time: >80 Hours