DIY LED - Nichia issues and other advice

[Deebo]

I am re-doing my LED fixture that has been sitting for about a year while I moved. There are around 150 LEDs total but now that I am putting everything back together, I am running into an old issue that never got resolved. Out of my 42 Nichia 4500k LEDs that I got from LEDgroupbuy a couple years ago, 25 no longer work. The current passes right through the LED star as if it wasn't there. This problem is exclusive to my nichias and I even have a few of the dead ones that I never soldered so I don't know how I could be the cause of this.

 

Whats going on here and can I somehow fix them?

 

 

Also, since it has been about 2 years since I researched all this I am curious if there any any changes in LED color choice. I went through Evil's color guide and I seem to be following that well but I'll post my choices anyway.

 

40 Nichia 4500k

32 Cree Royal Blue

10 Luxeon M Royal Blue

20 Rebel Cyan

25 Cree Blue

6 Rebel Lime

20 Hyper Violet

18 True Violet

 

Controlled by a Storm X with Meanwell LDDs

 

I think the only difference I am seeing vs current setups/advise is that I have fewer Limes. Anything else you guys spot or places to improve?

 

Obviously not a nano tank but I really like the quality of replies from the LED community here.

 

[evilc66]

First thing you want to do is to check each LED to make sure they are actually working. While the LEDs may look dead, they may be fine and having power shunted around them, say from a short to the heatsink. It's highly unlikely that 25 LEDs all shorted closed at the same time. This will give you a good indication as to where to look next.

[Deebo]

So this is the problem I'm having. Most of these LEDs show between 004-008.

 

http://imgur.com/2RSqfIW

[evilc66]

Diode check doesn't work on all meters with LEDs. The only sure fire way to check is to put 3v across them (from a pair of AA batteries in a holder, or a variable power supply if you have one). If it lights, it's good. If not, put it aside.

[Deebo]

Alright!

 

22 out of the 24 work fine with my 2 AA battery holder, but only 4 of those work when powered by a 300mA meanwell ldd; all the others just flicker on then stay off.

 

Im glad they work though. When I get them into a string will the flickering ones work as intended?

 

Also, think my color mix is ok? I may be getting another 12 limes

[evilc66]

Strange. The only reason I can think of for those LEDs to work with the AAs, but not the LDD is a thermal expansion issue causing the bond wires to lose contact once things heat up a little more from the increased current (the AAs would have a lower voltage compared to the LDD, and as such, a lower current). I've never worked with Nichia LEDs before, so I can't really say just how durable they are compared to Cree or Lumileds.

 

Try hooking a few up in a string and see what happens.

[Deebo]

Hmm no luck in the string either. I had 3 and they would all flicker on then stay off.

 

Im using a LDD 300 so do you really think its a current issue?

 

Even with my storm connected and the ldd dimmed really low it still does the same thing

[evilc66]

Without having them in hand to test them and figure out exactly what the issue is, I'd say it's pointless trying to make them work. There is something at fault that we can't pin down easily. It's time to cut bait and get some replacements.

[Deebo]

That is what I'm thinking too. What do you recommend for a good white? I like the luxeon Ms but I have my fixture about 4' or so above my tank and the M reflectors are pretty big. I have a few 3ups that I got from Steve's that work well with the 3up lenses I have.

[evilc66]

A good direct replacement would be a Lumileds Rebel ES. There are high CRI versions that will get you close to the Nichia (the 219 is already a pretty high CRI part). As an alternative, you could look at the Bridgelux Vero series. They are larger multi-chip arrays, but the color is fantastic and can replace multiple Nichias easily. But, like the LuxM, the reflectors are big. Reflectors are good though, as they are much better at even light distribution compared to TIR lenses.

[Deebo]

Oh ya I don'y have an issue with the reflectors at all. They are big but big only matters because the mounted stars take up so much space already. The Lux Ms reflectors take up about the space of 4 stars so it's 1-1.

 

I will look into those. Thanks again!