LED lighting on a budget!

TheFishMan65 said:
You realize I am going to have to add this to the summary :) Was this all from the datasheet or is there another good link?
Click to expand...

From Crees app notes and from examining a lot of commercial designs and reading engineering journals.

I had to focus on it for that 'different' build I did.

Hey, I got it to you before you put up your summary... :celeb1:

jpccusa said:
That's it - I'm returning my 2 fans... LMAO
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Fan's and their habitats are being devastated. SAVE THE FAN needs your money - send it all to me. I'll make sure the right person, er, I mean organization gets it.

Seriously, properly applied fans are a huge cooling multiplier and it doesn't hurt to have one, especially if you have a restrictive enclosure. What this really means is you can run no fans in open style fixtures, or less fans in your more closed fixtures, or your fans slow enough to start reliably but not noisy fast.

katchupoy said:
this is pointing at: the emitter, the star, the solder points, and contact between star and alum sink.

And based on Kcress latest research, my rig right now is fine and safe.
Click to expand...


We all use stars and stars are really excellent at conducting the heat away from the LED's chip. The difference between the die and the back of the star is only about 10C. So if we keep that spot - the back of the star - down around the aforementioned temperature we are also keeping the dies temperature wayyy below rapid aging temps.

Yes your design is way more than adequate.

Floyd R Turbo said:
Thank you kcress!!
Click to expand...

:beer:
 
Thanks Kcress and others created a wonderful thread. This is exactly what i am looking for. I am very exciting to start one myself. However, i have a few questions and hope to clear it up. My plan is building two 24 LED (50/50) fixtures for two of my tanks. However, with my limited budge & learning purpose for now, I am going to build one first. Here are my questions from the original diagram that Kcress provided.


1. Can I just build only 24 LED (4 strings) for now and add the other later? I am thinking the answer is yes but would like to confirm with everybody. I guess it's just a matter of consuming the power.

2. Since this is undimmable build but i would love to have an option of turning on BLUE or/and WHITE array (12 LED each) seperately. Is there a way, that I can add the switches (one for BLUE and one for WHITE) some where in the diagram? This way, i can have the option to see all BLUE or WHITE or BOTH. If so then what kind of switches that I should use? In addition, is it possible to have those switches on timers?

Please let me know. I really appreciate your input. Any comments or suggestions is greatly appreciated.

Thanks,
Ken
 
If you look at post 4994 in this thread

http://www.reefcentral.com/forums/showthread.php?p=17783831#post17783831

And look at these pics of fishman's driver board on the DIY Driver thread

http://www.reefcentral.com/forums/showpost.php?p=16818982&postcount=619
http://www.reefcentral.com/forums/showpost.php?p=17221092&postcount=859

this board can drive up to 48 LEDs and has 2 'sides' that can be fed by separate 24VDC power supplies which is what you probably want to do instead of mixing royal blues and cool whites.

The board has PWM inputs too though as you stated you wouldn't use them, but you would have the option. You could run 2 PSs on one board and control each side via timer.
 
Hey kcress, I just was looking up some lumen/watt info on Cree's website and found a data sheet for the XP-E. This has a table in it labelled "Relative Flux vs Junction Temperature". For If= 350 mA the flux is 100% at 25C and drops linearly to 70% at 150C (maximum junction temp).

What this looks like to me is that you lose lumen output on a linear scale as you junction temperature increases. And that was only at 350 mA. I would think that the goal would be to maintain as low a junction temperature as possible, within reason.

Granted that at a junction temp of 65C or 150F you're still at 90% of peak flux.

Any thoughts?
 
kttran_2005 said:
1. Can I just build only 24 LED (4 strings) for now and add the other later? I am thinking the answer is yes but would like to confirm with everybody. I guess it's just a matter of consuming the power.
Click to expand...

Yes! None of these strings are in parallel. They are all completely independent. Add and subtract as desired.


kttran_2005 said:
2. Since this is undimmable build but i would love to have an option of turning on BLUE or/and WHITE array (12 LED each) seperately. Is there a way, that I can add the switches (one for BLUE and one for WHITE) some where in the diagram? This way, i can have the option to see all BLUE or WHITE or BOTH. If so then what kind of switches that I should use? In addition, is it possible to have those switches on timers?
Click to expand...

Since they're independent you may turn any on and off as you wish. If you want to turn all of each color on or off you can just add a switch into the supply line leading to the first distribution terminal block of each color - that's the power supply line.

Use any switch rated at the current and voltage your setup needs. Most any toggle switch you buy at a hardware store will work.

Then later when you want to run dimming you can install current drivers in place of the power supply(s) and remove all the adjustable resistors. Doing this then puts all the strings in parallel and they're no longer independent. So you'd need to check the current flows in each string and make sure they're all reasonably balanced.
 
Floyd R Turbo said:
Granted that at a junction temp of 65C or 150F you're still at 90% of peak flux.
Click to expand...

That's why I'm not suggesting we run our LEDs at a much higher temp, the output efficiency would definitely take a big hit. The slight loss is well worth it to me to have a fixture that's light as a feather and doesn't add any noise to a system.

You now have me interested in the weight of my recent build. Hang on....

2.2 lbs! Most of that is the Meanwell. I could hang it with dental floss.

Anyway, any lighting system has trade-offs. I actually have and incandescent light that is nice and white instead of yellow. Trade-off - It has only an 8 hour lifetime!

Same with these LEDs. Cree picked the 350mA for that chart, they picked that number for marketing reasons, so they could show great efficacy.

But we run our fixtures at 700mA! We do this for a reasonable trade-off of efficacy to cost. You do realize you could refrigerate the LEDs with drilled heatsinks, pump refrigerant through them and have them be more efficient? But we don't, ("we" meaning sane people), for that would be cumbersome and expensive.

My point is, a trade-off we should be making is to have reasonably light, efficient, and inexpensive as possible fixture builds. That means trading off heavy fan-encrusted fixtures for light-weight efficient builds with lifetimes that still exceed by 2x what's really required.

Viva la 158F! :beer:


That Solid-State Lighting Report chart is actually pretty accurate!
 
Yeah I have another one from the seminar I went to that had more data on it for other lighting types, linear fluorescent, HPS, Pulse-start MH, etc.

Also another chart I cannot find but it shows Haitz's Law of LED Lighting Output Increasing / Cost Decreasing. In summary, the lumen output is increasing 20 fold per decade, while the cost per lumen is decreasing by 10 fold per decade.

I think after all this discussion, the only reason I can think of to use the individual heat sink would be so that I can aim each lamp and tweak the coverage, or change the layout if desired. Other than that, it offers no cooling benefit and costs about $75 + time.
 
Thanks Kcress. I don't want any dimming. I like simple designer and cost effective. Your suggestion is what i am looking for. Thanks
 
I am trying to order the equipment you specified for the XCREE LED's. The power supply is no longer available. I have no idea what type of power supply I could use to replace the one you specified. Is there any way you can help with a differant power supply? Is this link the same Power Supply you listed?
http://www.interinar.com/fs-20024-1m.html
 
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Meanwell makes a large line of power supplies. You can find them many places, they look exactly like the one in that link. The key is to figure out what size you need, for the board I discussed the 240W has 24 VDC and 10 A on each side, if you fill that side. The driver board is going to be different of course based on the design so you have to match driver board and PS.
 
OK, seriously I understood your post because it was well written for a beginner. What is a driver board? Also, where am I going to mount all of these differant pieces? Can anyone show me a picture that would show what I can mimic? I am kinda new to all of this. In my class, we had prebought kits... I know, sad.
 
I think there are ways to do with with a different type of power supply, made specifically for LEDs and meanwell makes those too. But i'm not sure. I just know what I've learned recently regarding the DIY driver and how it works. Someone else will have to take this. I'm new to LEDs too even though I'm in the commercial design industry - but those are all pre-made fixtures. There is definitely more than one way to do it so do your research. I read through that entire DIY Driver thread to see the progression of one idea to the next, which ended up with a driver board design that is extremely similar to ones I have personally seen in top-end streetlight and parking lot lighting fixtures.
 
Floyd R Turbo said:
Meanwell makes a large line of power supplies. You can find them many places, they look exactly like the one in that link. The key is to figure out what size you need, for the board I discussed the 240W has 24 VDC and 10 A on each side, if you fill that side. The driver board is going to be different of course based on the design so you have to match driver board and PS.
Click to expand...

I think I've found the Power Supply you are referring to. Meanwell SP-240-24. Seems to run around $65. Much more than the one originally described earlier. When you say "10 A on each side", do you mean that it has 2 sets of 24vDC outputs, each capable of 10A?
 
No, the DIY Driver board has 2 separate power supply connections. If you are running 48 LED, 24 on a side, you would need 500W (24 VDC, 20A) total to run that board. Due to the inherently different charachteristics of RB vs CW LEDs, if you ran 24 RBs and 24 CWs it would be better to run then on separate PSs, so you would get 2 24 VDC 10A PSs and connect one to each side. Again this is the DIY board only.

I believe (correct if I am wrong) that the Meanwell ELN-60-48 is a driver and power supply, but it can only drive 12 LEDs or something like that.
 
Meanwell ELN-60-48

Meanwell ELN-60-48

Maybe I misunderstood you - but from what I can tell on the MeanWell site, the Meanwell ELN-60 series driver does not function as a power supply.

So we're back to the power supply. Two of the power Meanwell SP-240-24 power supplies will run over $100. Is there a lower cost alternative?
 
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