Today mark 4 years 6 months usage of the Yetplus 6" LED downlight in my house.

Usage pattern 6 hours per night constantly for 12/39 of the lights, total hours is approaching 10k mark at 9.85k hours/light now.
None of them malfunction until now, but the intensity test using lux meter did shown degraded to 80% of original brightness when compare with those that seldom turn ON.

I won't say the brightness is durable, but the driver reliability is quite remarkable in my opinion.

This post has been edited by coolkwc: Jun 10 2020, 01:07 AM

I'm not sure whether your good lifetime is affected by under current LED or not.

Looking at your testing 1 and 2, i think you make a fundamental error there. 1st LED is constant current driven components, current decide brightness, not voltage. Whereas voltage is a by product of LED forward bias. Normally in LED driver, 2 specs was printed which is open circuit voltage, and current rating. That current is constant that will be sensed and controlled by tye driver.

You measured 17V from original PSU doesn't mean the PSU is output 17V. It means when series of LED running with xx current, the total series LED forward voltage is 17V and it clamp the PSU output and it will change based on tenperature. The hotter the LED, the smaller the forward voltage, and larger of LED current. So the driver current sense will adjust it so that the LED current is constant throughout the operation. One improtant things, the open circuit voltage of LED driver will be higher, say the LED forward is 17V, the open circuit voltage that the LED need to supply will be higher than that.

Your method of modifying is using constant voltage method, and only able to provide 16V in default as oppose to 17V, which means it will not provide enough current same as original design. In LED a slightly drop of forward voltage can means a huge reduction in current provided temperature is same. You can read the VI curve of LED online. This explain why your power reading is lower. It also means your LED can last alot longer because it operate in much lower current, perhaps 50 percent of intended current.

Furthermore i'm not surpise the laptop PSU can last so long time provided you only use perhaps 10 percent of the maximum capability. I based it with 5W per 50W max.

Anyway i did not read your following post except those in your link, so i'm not sure whether u found the answer afterwards or not. Really sorry if your 8 years test is not valid.

This post has been edited by coolkwc: Jun 14 2020, 01:29 PM

Sorry to say, you have no idea how the LED works because you are not in that field.

The current to LED need to be constant to achieve constant light output, and the constant current is controlled by the driver (PSU), not LED itself. They are two majority output control in PSU, which is constant voltage and constant current. Constant voltage suitable for load that varies the current based on dynamic load such as motor, computer and others majority of devices. Constant current is for load that need to strictly maintain its current throughout its operation such as LED and Li-ion battery charging.

I respect your passion and interest on electronics, but i just can't agree because it was wrong. Just let you know my background this year is my 11th years in EE field, currently work in local R&D centre of famous UK brand home appliances and we do design LED lighting that claim to withstand 40 years lifespan. I'm happy to exhange the idea if you would like to know more about LED driver design.

This post has been edited by coolkwc: Jun 15 2020, 09:19 PM

It is top 1 seller because it is cheap, not because is good.

For people who care about LED, they will avoid something too cheap yet with unknown light source (LED bead), not even the brand itself.

This post has been edited by coolkwc: Dec 27 2022, 04:05 PM