diy led lights

[xandrew245x]

I prefer the deep blue look, also I will be able to control how bright each color is, would only 12 whites be enough though?

 

[xandrew245x]

I ordered my leds, I chose a 2:1 ratio, and threw in a few normal blues as well, I'm going to try wiring them in parallel, and i'm going to use resistors as insurance in case one led were to go out.

I also decided on ordering a typhon controller, I don't want to build one yet, and if I do its probably going to be a timely project, so I will possibly just add it to my rig later.

Also, I plan on adding a splash guard to my light, how far does it need to be from the leds? I was planning on bolting a piece of acrylic onto the bottom of my frame, which would leave about a quarter of an inch of airspace in between.

 

[der_wille_zur_macht]

I ordered my leds, I chose a 2:1 ratio, and threw in a few normal blues as well, I'm going to try wiring them in parallel, and i'm going to use resistors as insurance in case one led were to go out.

Resistors aren't insurance - a fuse is insurance. The resistor is put in a parallel build (mostly) to allow convenient measurement of the current. Check this thread for a good discussion on parallel builds:

http://www.reefcentral.com/forums/showthread.php?t=1973462

Also, I plan on adding a splash guard to my light, how far does it need to be from the leds? I was planning on bolting a piece of acrylic onto the bottom of my frame, which would leave about a quarter of an inch of airspace in between.

A quarter of an inch is not very much at all. Unless you're talking a quarter of an inch from the face of the optics - then it might be OK.

 

[xandrew245x]

Its going to be a quarter inch from the face of the optic, and I meant to say fuses not resistors (smacks head)

I did a good bit of reading on parallel, and I think I understand it for the most part now, however i'm still not to clear on how many leds can go to a driver in parallel.

I have 4 drivers, and what I would really like to do is have the 8 cool whites on a driver and the 8 neutral on a driver, I would wire these in series, since there isn't much need or parallel there, however I would like to use the last 2 drivers for the 34 blues I have, of course wiring in parallel.

 

[der_wille_zur_macht]

Its going to be a quarter inch from the face of the optic, and I meant to say fuses not resistors (smacks head)

I did a good bit of reading on parallel, and I think I understand it for the most part now, however i'm still not to clear on how many leds can go to a driver in parallel.

I have 4 drivers, and what I would really like to do is have the 8 cool whites on a driver and the 8 neutral on a driver, I would wire these in series, since there isn't much need or parallel there, however I would like to use the last 2 drivers for the 34 blues I have, of course wiring in parallel.

Basically, when you go parallel, there are a few guidelines to help with design:

1) Each parallel string MUST be the same as all the others on that driver. You can't have one string with 10 of LED A, and another with 10 of LED B. You COULD have two identical strings, each with 5 of each LED, though.

2) On a given driver, each (identical) string must fall within the driver's voltage range. If you have a driver capable of 24 - 48v, you can't have a bunch of strings that only need 20 v. Think of it this way - from a "number of LEDs" standpoint, each string should be as long as if you were only running one string. So if you had a driver that normally took 10 - 12 LEDs, you need parallel strings with 10 - 12 LEDs. You can't put a bunch of strings on it that are only 9 LEDs.

(To be totally accurate, it's not the number of LEDs that matters, it's the Vf of the strings).

3) Assuming the above are followed, the current generated by the driver will be split equally among the strings. So if you have 2A and 4 strings, each will get 500mA. If you have 1A and 10 strings, each gets 100mA. And so on.

I've lost track of which LEDs and which drivers you're talking about in this thread, so as you're thinking about your design, keep these guidelines in mind. Or repost the models of LED, their Vfs, and the models of driver.

 

[birdsandsoap]

I'm tagging along!
I can't wait to see pics of your frame and build!

Thanks for this thread, this is the first LED thread that I have had any success in understanding due to my zero knowledge of electrical jargon.

I have a 72 gallon bowfront and will be planning on a 36-48 LED set. I'm still trying to determine if I can actually build one myself or whether I should go with the ebay versions. They are in my price range, lol.

As for the moonlighting, I think I will be going for this one I found on ebay. It has a dimmable switch, and buyers seem to be happy with it. The price is nice so I think I will try it out. And the best part; all the work is done.

There is also a 48 LED kit on ebay that I am considering as well. However, I think I love the neutral and warm whites (at the least, I can say that I HATE the look of cool white LED Christmas lights on a house, haha) and I would personally like a blend of the warmer tones.

Give a look-see and tell me what you think! Thanks.

 

[der_wille_zur_macht]

There is also a 48 LED kit on ebay that I am considering as well. However, I think I love the neutral and warm whites (at the least, I can say that I HATE the look of cool white LED Christmas lights on a house, haha) and I would personally like a blend of the warmer tones.

Give a look-see and tell me what you think! Thanks.

Tell you what I think? Those LEDs are worthless garbage. You'd be much better off spending the same amount on something known-good.

 

[birdsandsoap]

Tell you what I think? Those LEDs are worthless garbage. You'd be much better off spending the same amount on something known-good.

Wow! That bad huh?

How many manufacturers make a 3W LED anyway? How many "inferior" LEDs are out there? I'm asking because I really have no idea, however, I just have to argue that more $ doesn't always mean better, right? Especially with these no-name-direct-from-over-the-pond versions. Honestly, I assume they are all being cranked out at the same plant and stamped with different names on them. I've been so careful trying to research before pulling the trigger on these, and I feel like I am still where I've started. sigh.:hmm5: I understand the security in going with the CREE LEDs because of their widespread use and success for this application, but the cheap side of me wants to take a chance on the no-name light kit, haha.

Like you've mentioned earlier, a lot of DIYers are using 3W LEDs only to run them at a lower output for various reasons. If I want the most bang for my buck, I wouldn't want to go all out with a high end product to only use it at half the potential. There are so many variables here. Sorry to dump on your awesome thread.

Either way, the DIY route seems to be more economical in the long run. I can't imagine what a custom mixed LED would cost from a retailer. I want a high quality custom light without the price tag. Is that too much to ask?

yes. yes, it is.

 

[xandrew245x]

Basically, when you go parallel, there are a few guidelines to help with design:

1) Each parallel string MUST be the same as all the others on that driver. You can't have one string with 10 of LED A, and another with 10 of LED B. You COULD have two identical strings, each with 5 of each LED, though.

2) On a given driver, each (identical) string must fall within the driver's voltage range. If you have a driver capable of 24 - 48v, you can't have a bunch of strings that only need 20 v. Think of it this way - from a "number of LEDs" standpoint, each string should be as long as if you were only running one string. So if you had a driver that normally took 10 - 12 LEDs, you need parallel strings with 10 - 12 LEDs. You can't put a bunch of strings on it that are only 9 LEDs.

(To be totally accurate, it's not the number of LEDs that matters, it's the Vf of the strings).

3) Assuming the above are followed, the current generated by the driver will be split equally among the strings. So if you have 2A and 4 strings, each will get 500mA. If you have 1A and 10 strings, each gets 100mA. And so on.

I've lost track of which LEDs and which drivers you're talking about in this thread, so as you're thinking about your design, keep these guidelines in mind. Or repost the models of LED, their Vfs, and the models of driver.

Okay, you lost me now, so your saying I couldn't run my XT-e royal blues on the same driver as my XP-E blues?

I kinda did something stupid, and I didn't label all of the leds, so now i'm not sure which all are royal blue, regular blue, cool white and neutral whites, I think I will be able to run the cool and neutrals on one driver, because they are basically the same led, just different colors.

I got the meanwell 48P drivers

I have 28 XT-E royal blues
6 XP-E blues
8 XP-GR5 cool whites
8 XP-G Neutral whites

I am using cree leds.

I have a feeling this is going to be difficult...

 

[birdsandsoap]

I have a feeling this is going to be difficult...

Well, I will be your cheerleader! Please post lots of pictures of the process!

 

[xandrew245x]

Bump, could really use some help!

 

[xandrew245x]

I have figured it out.

Driver A will run a string of 12 Royal blues
Driver B will run a string of 12 Royal blues
Driver C will run a string of 6 regular blues and 2 royal blues
Driver D will run in parallel two strings of 8 whites.

There will be a fuse and resistor after the driver on each string of leds.

 

[der_wille_zur_macht]

That sounds OK, though what's the forward voltage of the white LEDs at the current you'll use? I know some people have trouble with only 8 LEDs on the ELN drivers.

 

[xandrew245x]

FV is 3.2 at 650ma.

I did a little reading and some people say thermal grease is a better conductor, I already have all my stars stuck on with thermal grease, so what I plan on doing is putting thermal epoxy around the edge of the stars to bond it to the surface.

 

[xandrew245x]

FV is 3.2 at 650ma.

I did a little reading and some people say thermal grease is a better conductor, I already have all my stars stuck on with thermal grease, so what I plan on doing is putting thermal epoxy around the edge of the stars to bond it to the surface.

 

[der_wille_zur_macht]

You can't mix thermal grease and thermal epoxy on the same build. If you're not using screws, you need to use an adhesive. The grease is not an adhesive.

3.2 * 8 = 25.6 so in theory you're OK on a driver that wants 24v minimum. If I were you though, I'd buy two extra in case you need to end up going with strings of 9.

Also keep in mind that 650mA is a fairly low current for those LEDs, and the discussions we've had earlier in this thread assumed more typical currents - so you may find that with all your whites at a lower current the color is a little more blue than expected.

 

[xandrew245x]

So, even though the thermal grease didn't spill out to where I will be putting the epoxy, I still can't use it?

I'm not going to drill and screw every single led in, so I guess i'm going to get some rubbing alcohol and start cleaning all the grease off.

 

[der_wille_zur_macht]

Regardless of what material is between the components, you need a solid, high-pressure bond to ensure that boundary layer remains thin - when you glue, you really need to give the star (not the LED itself) a solid push against the heatsink to ensure this happens. When you use thermal grease and screw, you get good clamping pressure by tightening the screws down tightly.

If you just dabbed thermal grease on and then put glue around the edge, there'd be no good way to ensure there was a solid bond like this. Plus, you'll have a really small gluing area, and thermal epoxy is not a strong adhesive to begin with. And, you're leaving yourself open to contamination between the materials.

So yeah, I would take the LEDs off, clean them and the heatsink, and glue them all down with the proper adhesive.

 

[xandrew245x]

I already ordered my thermal epoxy, and I tried cleaning a star with alcohol and it works amazingly, cleaned 5 stars and the bonding surface in like 2 minutes, so overall, it will be pretty easy to do.

I'll hopefully be able to get them all glued back on tomorrow night(my epoxy will be here tomorrow) and then I can start wiring everything saturday, since I now understand how to wire it, I put 4 whites together in a parallel as a test, and I do believe that I can tell the difference between the cool and neutral.

You said about the way i'm wiring my whites, it will be a low current, do you think maybe I should order two more whites, and another driver and just run them in series so I can get the most current running through?

I'm starting to understand this a little more, and since they will be split, I will basically only be able to run them at half the capacity they could possibly run.

 

[der_wille_zur_macht]

You said about the way i'm wiring my whites, it will be a low current, do you think maybe I should order two more whites, and another driver and just run them in series so I can get the most current running through?

I would. If you're only going to run at 650mA you're underutilizing the XP-Gs. The ELN 60-48 in parallel is really only good for lower-power LEDs (XP-E, etc) IMHO. So either get another driver, or better yet, shift your plans a bit. For instance, take all 24 RBs you listed for drivers A and B and run them in two parallel strings of 12 on a single driver. Run it at 1.3A so both strings get 650mA. Then split the whites between the newly freed driver and the driver you'd originally planned to put two strings of whites on.