It is common that the led light becoming darker than before after using a while.

So what is the reason for this ? Here we are going to explain to you.

Driver damage

LED lamp beads are required to work at DC low voltage (below 20V), but our usual mains supply is AC high voltage (AC 220V). To turn the mains into the electricity needed for the lamp, you need a device called “LED constant current drive power.” which we simply called “ driver”.

As long as the parameters of the driver match the lamp bead, the power supply can be continuously used and used normally. The internals of the driver are complicated, and any device (such as capacitors, rectifiers, etc.) may cause a change in the output voltage, which may cause the lamp to become dark.

Driver damage is one of the top reason in LED luminaries issue and can usually be resolved after replacing the driver.

LED burned

The LED itself is composed of one lamp bead. If one or a part of it is not lit, it will inevitably make the whole fixture darker.

The lamp beads are generally connected in series and then in parallel – so if one of a lamp bead burns, it may cause a batch of lamp beads to be off.

After burning, you can find black spots on the surface of the lamp bead. Locate it, use a wire to connect it to the back of the lamp, short-circuit it, or replace it with a new lamp bead.

It’s a coincidence that the LED burns one or two at a time. But if it burns frequently, maybe it’s the driver problem – another manifestation of drive failure is burning the lamp bead.

LED light decay

The light decay is that the brightness of the illuminant is getting lower and lower – this situation is more obvious on incandescent and fluorescent lamps.

LED lights also can not avoid light decay, but its light decay rate is relatively slow, it is difficult to see changes by our eye.

However, there are some chance because of the inferior LEDs, or inferior light beads, or due to objective factors such as poor heat dissipation, resulting in faster LED light decay.


From all the above we can know that when you find the led light become darker you can first check the led chips and see if there are some beads burn down. Then go check your driver if it’s not the beads reason. All you need to do is to exclude one by one for the above reasons.  Then you will find the answers.


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