Cheap 1W & 3W LEDs - Page 1
Forum section: electronics / projects

author: xavier60
author_rank: Super Contributor
timestamp: July 01, 2020, 12:02:50 pm
content: As pictured below.I have used over a thousand of them from various sellers and have found them to have very good performance, without a single failure as far as I know.There is something unusual about a recent batch of 3W white LEDs.About 10% of them don't start emitting light until the current is about 10mA and matching the brightness of the normal LEDs at about 20mA.Does someone know what this means?

author: TheMG
author_rank: Frequent Contributor
timestamp: July 01, 2020, 02:15:34 pm
content: They're junk is what it means. High leakage current. You probably got sold factory rejects, or just really crappy quality LEDs.

author: xavier60
author_rank: Super Contributor
timestamp: July 01, 2020, 02:40:16 pm
content: Quote from: TheMG on July 01, 2020, 02:15:34 pmDo you use this style of LED also? I would like to find a supplier that can be trusted.Recently, I suspect that I was sent 1W LEDs instead of 3W.The LED on the left is a 3W from another seller. The other one was sold to me as 3W.

author: xavier60
author_rank: Super Contributor
timestamp: December 20, 2021, 09:48:10 am
content: Quote from: xavier60 on July 01, 2020, 02:40:16 pmSo far, I have put into service over 4000 of these cheap LEDs with no sign of performance or reliability problems.I have been getting mainly the 3W 6500K white type from ebay and Aliexpress sellers.

author: strawberry
author_rank: Super Contributor
timestamp: December 20, 2021, 10:37:34 am
content: silicon chips (could be rejects, vintage LEDs) but package (problem with bondwire, high thermal resistance, packaged by shady workshop)Mouser, Digikey.. comes with datasheets , data

author: xavier60
author_rank: Super Contributor
timestamp: December 20, 2021, 11:16:23 am
content: Quote from: strawberry on December 20, 2021, 10:37:34 amYes, all of those problems could be possible but I'm not seeing them. I recently got a light meter and found the brightness to be comparable to that of branded LEDs.The gull wing package are easy to hand solder to FR4 PCB.I do use branded SMD LEDs on aluminum PCB also.BTW, the aluminum PCB was made by PCBway.

author: Zero999
author_rank: Super Contributor
timestamp: December 21, 2021, 09:11:50 am
content: Quote from: xavier60 on July 01, 2020, 02:40:16 pmThe LEDs pictured appear to be red, rather than white. I agree, the one with the smaller die is lower power.The only advice I have is to buy from proper distributors. You might have good luck with cheaper parts on ebay & Aliexpress but not the same guarantee of quality.

author: xavier60
author_rank: Super Contributor
timestamp: December 21, 2021, 09:30:47 am
content: Quote from: Zero999 on December 21, 2021, 09:11:50 amYes they are red which I use few of. It's a little more difficult to judge the die size of white LEDs because of the phosphor. I have not had any more sellers try to trick me by sending 1W instead of 3W LEDs.Originally, I had no choice but to buy the cheap LEDs because the package is obsolete and I needed them as replacements to repair existing boards.I realize things can change so I buy 1000 at a time well in advance of my old stock running out to make sure they are good.

author: Zero999
author_rank: Super Contributor
timestamp: December 21, 2021, 10:32:42 am
content: Quote from: xavier60 on December 21, 2021, 09:30:47 amIf you power them at a really low current, try 1mA, so they just start to glow, it makes it easier to see the die.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 21, 2021, 06:37:55 pm
content: FWIW, I picked up some LEDs of that style, like back in 2012 or something I forget. Was back when they were fairly well established and cheap, but before the tight optimization of modern brand name parts. Were just no-name Chinese things.Anyways, the efficiency was modest (I don't have a way to measure it, but... probably in the 50-100 lm/W ballpark?), and the phosphor faded quite substantially over several years of typical usage, leading to a purplish glow and reduced light output.In contrast, replacing them with much smaller (but much pricier) Cree XTEAW-00-0000-00000HGE3 or XPGDWT-H1-0000-00GE7, at whatever it is, 100-200 lm/W, the efficiency gain is so dramatic that actual power dissipation is substantially lower. So they're smaller and don't get as hot to begin with. Have been using them for some years now with no apparent fading.Typical failures for LEDs in general, include chip quality: leakage, contamination, fractures, etc., reduced (blue) light output, etc.; chip bonding (bondwires, die attach); phosphor bonding (can physically fall off some types, e.g. completely-blue street lights); and phosphor aging (reduced yellow output, spectrum drifts blue or purple).Tim

author: rpiloverbd
author_rank: Regular Contributor
timestamp: December 23, 2021, 02:06:35 pm
content: Sometimes it depends on their origins.

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 07:34:08 am
content: Quote from: rpiloverbd on December 23, 2021, 02:06:35 pmAll from the same origin I hope!I started using them a bit over 2 years ago with no sign of trouble yet. Even the leakage turned out not to be a problem. I'm certain that the leaky LEDs would fail short circuit anyway which wouldn't be serious problem as I use separate current drivers for each string.I lately found that my Arlec White-Pointer torch has the same looking LED. The white temperature also looks the same as the 6500K LEDs that I mainly buy.https://www.bunnings.com.au/arlec-3w-led-white-pointer-torch_p4410686