Replacement LED question (pictures)

[Jonathan Troutt]

hey guys so I’ve been trying to replace the warmer white leds in my fixture with 10k. I’ve order twice and each time I am supposed to be ordering a 3w 10k Chip.

Well they are definitely 10k but they don’t look the exact same and I worry they are not 10w. Pictures explain better

The one being held by the tweezer is the one that came off the light.

 

[Dr. Reef Verified Sponsor]

size of the led wouldnt be a true conclusion on wattage, This is not my field but lets see what others have to say.
#reefsquad

 

[Jonathan Troutt]

size of the led wouldnt be a true conclusion on wattage, This is not my field but lets see what others have to say.
#reefsquad

That’s fair and I know I should put a meter on it to find out for sure. Just don’t have one currently. I am gonna go ahead and swap them. I guess I will find out

 

[Jonathan Troutt]

10k White led swap and installation of diffuser doesn’t look half bad

 

[TheEngineer]

size of the led wouldnt be a true conclusion on wattage, This is not my field but lets see what others have to say.
#reefsquad

Agreed. I'd say those are similar if not the same wattage if I had to guess but it is only a guess. One way to find out is to hit it with 15W and see what happens

 

[Jonathan Troutt]

Agreed. I'd say those are similar if not the same wattage if I had to guess but it is only a guess. One way to find out is to hit it with 15W and see what happens

Appreciate you responding. The seller rates them as 3.2-3.4v. But at 3.4v they only pull 400mA. Which is just shy of 1.5w. At 3.8v they pull 800mA.

 

[theatrus]

Appreciate you responding. The seller rates them as 3.2-3.4v. But at 3.4v they only pull 400mA. Which is just shy of 1.5w. At 3.8v they pull 800mA.

LED's don't "pull" - what you're seeing is the forward voltage rising as current rises, which is a normal effect within range. As you push more current through the system expect this to rise until destruction

 

[Jonathan Troutt]

LED's don't "pull" - what you're seeing is the forward voltage rising as current rises, which is a normal effect within range. As you push more current through the system expect this to rise until destruction

Yes I know they don’t “pull”. So let me rephrase if the seller lists their voltage rating as being 3.2-3.4. And you drive them at 3.4CV and they only sink 400ma then wouldn’t that mean that according to the sellers specs they are not 3w LEDS.

Now if you drive them using CC and set the current at 800mA. Then voltage rises to 3.8v. Which is way above specifications that the seller provides.

Is my vocabulary more accurate this time around.

 

[theatrus]

Yes I know they don’t “pull”. So let me rephrase if the seller lists their voltage rating as being 3.2-3.4. And you drive them at 3.4CV and they only sink 400ma then wouldn’t that mean that according to the sellers specs they are not 3w LEDS.

Now if you drive them using CC and set the current at 800mA. Then voltage rises to 3.8v. Which is way above specifications that the seller provides.

Is my vocabulary more accurate this time around.

Most manufacturers quote Vf at one test current (commonly 350mA). The Vf range is likely bin variation, since it’s commonly a 200mV range.

Datasheets should provide a Vf curve and bins. Example:
https://www.lumileds.com/uploads/571/DS144-pdf
You can see the bins are 200mV on page 24, and the curves on page 14 on.

If we look at page 16, we can find the curve for Royal Blue for the Luxeon C. It’s nowhere near a 400mV rise across 400 to 800mA.

What can cause your 400mV rise? Crappy LED process for one (these are not premium products). User measurement error (are you also measuring the voltage drop in the wire to the LED?). Poor LED packaging causing the same (tiny bond wires in these dome top packages).

 

[Jonathan Troutt]

Ok first let me say sorry if my response came off as me being a bit cheeky I didn’t mean for it to sound that way. So let me ask you a question where can I find These dumb style LEDs in 3 W that our quality LEDs.

 

[theatrus]

Ok first let me say sorry if my response came off as me being a bit cheeky I didn’t mean for it to sound that way. So let me ask you a question where can I find These dumb style LEDs in 3 W that our quality LEDs.

No worries! I descended fast into the science camp myself.

As far as better or worse of these some style LEDs, I’m not sure the actual sources or manufacturers. I always suspected it’s a bunch of marginal dies that are cut and salvaged by a third party into these dome packages.

Even though the LED isn’t really 3W at the expected drive current, most of the fixtures using them underdrive out of the box so they aren’t expected to perform at max current anyway.

 

[Jonathan Troutt]

No worries! I descended fast into the science camp myself.

As far as better or worse of these some style LEDs, I’m not sure the actual sources or manufacturers. I always suspected it’s a bunch of marginal dies that are cut and salvaged by a third party into these dome packages.

Even though the LED isn’t really 3W at the expected drive current, most of the fixtures using them underdrive out of the box so they aren’t expected to perform at max current anyway.

Yeah that’s unfortunate because I’ve been playing with the idea of swapping drivers in my fixture to a mean well. Better support for those and if I did that I would want to drive the LEDs at close to 3w maybe 80-90 percent. Would they hold up and last or not?

So the question now is do I buy new lights or just deal with it

 

[LionHeart2017]

You will probably find at full power you might bleach coral, think that's why they are mostly under driven?

Im also looking to swap to mean well drivers in my mars aqua black boxes

 

[Jonathan Troutt]

You will probably find at full power you might bleach coral, think that's why they are mostly under driven?

Im also looking to swap to mean well drivers in my mars aqua black boxes

I am aware of this but I still want the option to do so. Maybe I want to highly diffuse my lights or have them up higher than most or maybe both

 

[LionHeart2017]

As long as you can keep them cool enough at full power they should be fine