# Review: Satistronics 20watt blue LED



## blasterman (Apr 15, 2010)

Why is the _world_ would you need a 20-watt blue LED? Well, since I work with reef tank lighting, I'm trying to replicate the blue intensity of 14-20k Metal halide lamps for PAR reasons. Messing around with 3-watt emitters just aint cutting it.

I looked closely at Phlatlight and Ledengin, and didn't see too many options there. Perhaps Phlatlight, but big blue ones are still pricey and never in stock. Bridgelux is ignoring my pestering to make a blue LED.

However, since I've been using 3-watt blue and red Satistronics for plant lights, I decided to give their 20-watt blue monster a try.

Surprisingly, it's a well made emitter (actually an array of 16 smaller ones). At it's top rated 18 volts it's supposed to produce 400 lumens, which I don't dispute, but I don't have testing equipment. However, I did have a 3watt blue Cree XRE for comparison. I shot a picture of the Cree at 700mA (current regulated )and the Satistronics at 18volts fixed with 1ohm resistor in the same orientation and same manual camera settings against some curtains. I don't have a current regulated driver on the shelf big enough for the 20watt at the moment, but that should be close enough for reference.

One difference you can't pick up in the shots is color. Regular Blue Crees tend to often be very cyan, while Satistronics and BestHongKong Blue emitters can range to almost Royal Blue. This emitter is somewhere in between.

I should note this is the only emitter I've worked with that with even averted vision was physically painfull to view. Heatsink requirements are also pretty hefty, and a big HeatsinkUSA brick was required to keep the emitter warm to the touch. I've got two of these on my 10gallon tank, and thinking about getting a third. The list of diabolical applications for an emitter like this is endless; highly discouraging security lights, faking a UFO invasion on halloween, growing a lot of lettuce, etc.


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## subhuman (May 19, 2010)

Hey blasterman,

Apologies for bumping this old(ish) thread, how are you getting on with these?

I have a few 10w versions on order from Satistronics, to place side by side with a Bridgelux array (experimental reef lighting) - have you used this version yourself?

I've also seen you mention that you've run Satistronics (3w) from a 'laptop brick' as opposed to a CC driver? How is that working out for you? I'm interested to know if you run them in series, straight from the supply (in numbers to total supply voltage of course!) - without resistors etc?

Cheers,
sub


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## blasterman (May 20, 2010)

I did run into some issues with the big Satistronics, but they were more interesting than anything else.

First, the color isn't as deep as their 3watt LEDs. Satistronics 3W LEDs are nearly identical to royal blue Crees, but about 25% less bright. I thought the 20watt versions would be the same color, but they aren't. They are between RB and standard blue Crees, which is very Cyan. While not a show stopper, about 90% of us prefer royal blue for reefing. 

Another issue is the 20watt version when fired up to full power are rather dangerous to use. First, they are a terror on your eyes and worse than 400watt reef metal halide. Next, they'll ignite any object placed within a few inches and will burn through plastic in a matter of seconds. Since I like to use acrylic covers over my tanks this created a problem. Setting a fire with a LED like a laser is actually kind of fun at first, but then there's the issue of trying to epoxy optics over an emitter that does this. The epoxy soon melts.

So, the 20watts are sitting in a box waiting for another project. In the mean time I contacted Satistronics, and they said they'd look at making a 440nm blue in 10-20watts, which should solve the problem. Color will be awesome for reefing and green-houses, and at 10watt it will eliminate the need for 3watt RB Crees. 

As for power supplies, I use both LED current regulated and fixed voltage. In most cases I don't need current regulated and fixed voltage supplies are typically cheaper, but a tad less efficient.

For instance, I have a box full of 18.5 volt 6.5amp laptop bricks. I run 5 white or blue LEDS in series, and this delivers 3.7 (3watts) to each. No need for resistors. I just keep throwing a series of 5 to get my light value. Real easy. 

A fixed voltage Mean Well typically has a voltage adjustment range, and this is certainly more flexible than a laptop brick because you can tweak the voltage to match what you want to do. Also, Mean Wells are cheaper and better made than laptop bricks. However, I've got that case of laptop bricks so I might as well use them. Plus, laptop bricks are sealed and won't die if a splatter of salt gets in them.

Oh yeah, one piece of advice for reef lighting. If you want better color, don't use cool-whites. Use neutral-whites instead at about a 2:1 ratio of RB/neutral-white. I've been following the crowd on cool-whites and not getting good color in my tanks, and on a hunch switched to neutrals. I got much better color, with more purple/pink/orange. If you don't believe me, just try two RBs with a neutral in between them and hold it over a part of your tank. The color improvement over cool-whites is impressive.


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## Nil Einne (Jul 27, 2010)

Out of interest did you agree to buy a number of those royal blues or did you just explain why you thought they'd sell and they decided to make some and see how they sell?


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## lyyyghtmaster (Jul 27, 2010)

I too would enjoy some soupy-chewy-thick, palpable-silver-jazzy high-muchness 440nm LEDs!!! They're not available from CREE at all, probably because they're using all the deeper ones in their whites, and Lumileds won't guarantee a 3-bin in small quantities. If these 10W LEDs do become available I likely would be interested in snatching some up!

As an aside, that's amazing that the 20W model will ignite/melt things! I have been aware since LuxI that blue in particular causes noticeable skin heating up close, but these sound like they take that to a totally new and dangerous level! How do you collimate them, reflector?

I don't have a reef tank but I do enjoy a good act03 for halloween! I apply a Rosco theatrical lighting gel (perhaps 349x can't remember)to filter out most all the green and blue but pass the 420nm and an insignificant faint band of red. Very cool background effect! I'm waiting for 420nm to become available affordably in LED. 

Thanks for the interesting thread!


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## csshih (Jul 27, 2010)

20W from a LED would ignite things? this interests me..


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## blasterman (Jul 27, 2010)

The 20watt LED will quickly melt through opaque plastic if it's placed in front of it. 



> Out of interest did you agree to buy a number of those royal blues or did you just explain why you thought they'd sell and they decided to make some and see how they sell?


 
Bingo. 

I now have a 10watt, which by eyeball estimate I put around 445nm. Compared to a royal Blue Cree it's just a bit deeper in color.Given the rarity of power LEDs below typical royal blue wavelength, and considering it's an even rarer 10watt version, it's safe to say I'm not parting with it. My main intent is to use it for reefing, and commercial reef light makers will likely soon figure out the 10watt 'Extreme Royal' can cut their fixture costs in half over 1-3watt based versions.

Again, the 20watt versions are fun to screw around with, but the wavelength is closer to 465-470nm and more like a standard blue Cree. Aka 'Windex'


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## Axkiker (Jul 28, 2010)

Okay you all lost me on this whole setting stuff on fire with a Blue LED

Im getting ready to order some of the high output bridgelux blue arrays to use for and underwater project.

Are you all telling me they will melt through my lexan lens?????


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## blasterman (Jul 28, 2010)

No, they won't melt anything clear. I used clear plastic optics on these mounted less than 1/4 inch away from the top of the domes and there was no problem, although optics got warm. 

At worse they might soften some glues after awhile.

I was testing these on my reef tank and set the heat sink on the side of my tank not worrying about if it was running or not. LEDs run cool, right? It only took a few seconds for the emitters to vaporize quarter size holes in the plastic trim on my tank.


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## dieselducy (May 12, 2011)

I have a Royal Blue Luxeon Rebel in my surefire and if i put paper near the LED it will smoke it!! I wonder if it is dangerous to look into the light itself?


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## CKOD (May 12, 2011)

dieselducy said:


> I have a Royal Blue Luxeon Rebel in my surefire and if i put paper near the LED it will smoke it!! I wonder if it is dangerous to look into the light itself?


Quite  All of the power LEDs we usually play with have eye safety warnings in their datasheets. However most white high power LEDs have that "oh *!#@$!#@$ thats bright" reaction, however the eyes arent that sensitive to blues, especially deep ones like royal blue. The power output is still the same, actually higher then white LEDs since they dont have phosphor losses. (I.E. a royal blue XP-E and a white XP-E driven at the same current, the blue LED will output more power (watts), despite looking dimmer)

And since power into the eye, not lumens, is what causes problems, you could cause damage to the eye without it seeming that bright "Oh, my flashlight is much brighter, this isnt *that* bright, so it cant be that dangerous"


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## Harold_B (May 13, 2011)

Well said CKOD. Thanks for posting that. Eye safety isn't just about lasers after all.


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## CKOD (May 13, 2011)

Harold_B said:


> Well said CKOD. Thanks for posting that. Eye safety isn't just about lasers after all.


 
Yep... in addition to the thermal damage of the retina, there is also, http://en.wikipedia.org/wiki/High-energy_visible_light a "potential for a photochemical induced retinal injury resulting from radiation exposure at wavelengths primarily between 400 nm and 500 nm." The reference for that is ANSI too, not some hokey pokey news report or questionable source.

Dont blow it out of proportion, but treat it with the same caution you would if it were a high power UVA source instead of royal blue.


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## blasterman (May 15, 2011)

We use the 10watt, 445nm version of these LEDs quite a bit for salt water reef lights, and I can assure you they will cause eye damage at full power. I run four of them at 1amp each, and it's staggering. Good for coral growth though. The standard blue verisons are inconsistent in terms of color, but the 445nm versions are pretty close to the mark.


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