How to Test a Capacitor With a Voltmeter

Capacitors are often the unsung heroes of electrical circuits, storing potential voltage to be released on demand, much like a battery. They are often overlooked until one goes bad, causing an entire device to malfunction or fail. A digital voltmeter, also known as a multimeter, is useful for testing whether a capacitor is holding a charge, and this process can be done quickly and easily.

Things You'll Need

• Digital voltmeter

Instructions

1. Discharge the capacitor. Use a wire to connect the two leads of the capacitor, jumping them and discharging any stored voltage.

2. Set the voltmeter to read in the high ohms range, somewhere above 10k and 1m ohms.

3. Touch the multimeter leads to the corresponding leads on the capacitor. Capacitors are directional, so you will want to be sure to identify the positive and negative leads.

4. Watch the meter display. It will read one of two results. If it starts at zero and then starts moving toward infinity, eventually settling there due to the infinite charging from the multimeter's battery, the capacitor is in good working condition. If the meter stays at zero, the capacitor is not charging, meaning it is bad.

5. Check your results with a known working capacitor of a similar type to make up for any anomaly with your meter.

Tips & Warnings

• For smaller capacitors, or to make a wider range of tests, an ohmmeter or a device designed to measure capacitance may be more useful.

• Be sure the capacitor is fully discharged before testing with the voltmeter, as not doing so destroys the capacitor.

References

• RepairFAQ.com: Capacitor Testing, Safe Discharging and Other Related Information

Resources

• ScienceBuddies.org: Electronics Primer: Using a Multimeter