How to Test LED Lights?

- Mar 20, 2020-

How to Test LED Lights?


Testing LED lights is simple with a digital multi-meter, which will give you a clear reading of how strong each light is. The brightness of the LED while you test it will also indicate its quality. How to test, then?


Using a multi-meter

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1.  Purchase a digital multi-meter that can take diode readings. 

Basic multi-meters measure just amps, volts, and ohms. To test LED lights you will need a multi-meter with a diode setting. Check online or at your local hardware store for mid-to-high-range multi-meters, which are more likely to have this feature than inexpensive models.

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2.  Hook up the red and black test leads. The red and black test leads should be connected to the outlets on the front of the multi-meter. The red lead is the positive charge. The black lead is the negative and should be plugged into the input labeled "COM."

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3.  Turn the multi-meter dial to the diode setting. 

Turn the dial on the front of your multi-meter clockwise to move it away from the "off" position. Keep turning it until you land on the diode setting. If it is not labeled explicitly, the diode setting may be represented by the diode circuit symbol.

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4.  Connect the black probe to the cathode and the red probe to the anode.

Touch the black probe to the cathode end of the LED, which is usually the shorter prong. Next, touch the red probe to the anode, which should be the longer prong. Be sure to connect the black probe before the red probe, as the reverse might not give you an accurate reading.

Make sure that the cathode and anode are not touching each other during this test, which may prevent the current from passing through the LED light and hinder your results.

The black and red probes should also not be touching each other during the test.

Making the connections should cause the LED to light up.

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5.  Check the value on the multi-meter's digital display. When the probes are touching the cathode and anode, an undamaged Led light should display a voltage of approximately 1600 mV. If no reading appears on your screen during the test, start again to make sure the connections were made properly. If you have performed the test properly, this may be a sign that the LED light is not working. 

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6.  Evaluate the brightness of the LED. When you make the proper connections to test your LED, it should light up. After noting the reading on the digital screen, look at the LED itself. If it has a normal reading but looks dim, it is likely a low-quality LED. If it shines brightly, it is probably a high-efficiency LED light.