[rives]

I haven't seen anything on here about the XtremeLED fixture, and was wondering if I had missed it. It was apparently called the StealthLED before (I wonder why there are only about 4 names that all of the manufacturers like to name their LED's?). I don't see anything in GP73LSC's compilations of LED data, and a search only turned up one mention of it.

If this thing is actually what it appears to be, I may have to re-think my very low opinion of CAP's products. It appears to use Osram Golden Dragon + LEDs, looks like it uses a damn big heat sink, and apparently uses 660, 625, 470, and 455nm leds. I've put a call in to see what proportions of each they are using, but haven't heard back yet. I like the small form factor (9" x 9" x 4") which would allow you to scatter them around the canopy in order to achieve even illumination, as opposed to the larger fixtures that concentrate too much power in too small of an area. They also make a cable to daisy-chain the power from one fixture to the next, up to a maximum of 10.

In a quick search this morning, I've found them for a low of $300 up to about $400. If the components are of the quality that they appear to be, it looks like a pretty damn good deal. Maybe we are turning the corner on quality commercial offerings!

Any experience with them?


https://www.randmsupply.com/images/li...meLEDSpecs.pdf

[setaemies]

At 42 leds and 130 watts, sounds like those little semiconductors are working pretty hard. Also 80 to 90 uE with that wattage sounds like efficacy in the low 20'ish% range? Might still beat some chinese made crap though.

[FunkBomb]

I've wondered the same thing about this unit. At plantlightinghydroponics dot com it's $299.90 which isn't bad. The cord piggybacking sounds like a perfect way to make a nice even canopy too.

-Funk

[rives]

Well, tech support was absolutely no help. The units are built by someone else, and he didn't have any idea who it was or how to contact them. He also didn't know the head count on each color or any other details other than he knew that it would void the warranty if I removed the acrylic cover and installed lenses on the LEDs.

Originally Posted by setaemies

At 42 leds and 130 watts, sounds like those little semiconductors are working pretty hard. Also 80 to 90 uE with that wattage sounds like efficacy in the low 20'ish% range? Might still beat some chinese made crap though.

The efficacy would be dependent on at what distance the ppf measurement was taken, which of course the fellow didn't know. If they are GD+s, they are some of the most efficient LEDs available at this time.

*edit* I found an old YouTube video that shows what appears to be the same unit, with a nameplate that says it is a model SGL140 from StealthLED.com. Going to that site takes you to StealthGrow.com, and although the model number looks like it is from their line, it isn't currently offered by them. Perhaps they are only selling it through other vendors?

[GP73LPC]

thanks for the headsup...

first i've heard of these, i will add them to my LED Retailers thread...

[analogue]

I read about the company, California Lightworks, that makes them, at this blog.

3 watts each, but 120 degree angle.

PLH has the cheapest price on them.

[asde²]

Originally Posted by rives

The efficacy would be dependent on at what distance the ppf measurement was taken, which of course the fellow didn't know.

you mean ppfd not ppf, because ppf (they dont mention ppf do they? whatever, what they state must be ppf the way they describe it) is measuring the raw output from source (in this case led's) and not a measuerement for a given area (which is why ppfd is worse than lumen to measure a bulb)


what remains is that this light is very ineffecient in terms of lifetime and given light/photons per watt

[rives]

Originally Posted by asde²

you mean ppfd not ppf, because ppf (they dont mention ppf do they? whatever, what they state must be ppf the way they describe it) is measuring the raw output from source (in this case led's) and not a measuerement for a given area (which is why ppfd is worse than lumen to measure a bulb)


what remains is that this light is very ineffecient in terms of lifetime and given light/photons per watt

I would think that the ppf figure would be whatever struck the instrument wherever it was placed, and is put in context by the distance measurement. I've seen numerous references to ppf requirements for plants, which would be at the plant level, not the light source.

How did you arrive at the conclusion that it is inefficient and short-lived? The micromole figure gives no distance at which it was measured, so that figure is nearly worthless. The projected lifetime is 50-80,000 hours, which seems pretty standard. If the LEDs used are the GD+, then the efficiency is only surpassed by the Cree XPE as far as I know. Has anyone seen other European or American LEDs that use the same package form factor as the GD+?

[asde²]

about the efficiency/lifetime - what setaemis said;

they use a very high current which means less efficiency, more heat and less lifetime so that in the end cheap chinese 3w emitters running at low current may be even more efficient even if they use LH W5AM instead of LR W5AM.

Originally Posted by https://www.gavita-holland.com/index.php/home/item/lumens-are-for-humans.html

Photosynthetic Photon Flux (PPF)

Photons are counted per second as we count a flow or flux of photons. If you count all the photons that a lamp emits in the PAR spectrum per second you get the Photosynthetic Photon Flux (PPF). The only way you can measure this accurately is in an integrating sphere, the Ulbricht sphere. So the PPF is measured in µmol/s and represents all the photons in the range of 400-700 nm per second. But how much ot that will reach your plant and at what distance?

Photosynthetic Photon Flux Density (PPFD)

Let's say we mount the lamp in a really good horticultural reflector, which has a total efficiency of 95%. That figure means that of the original 100% light of the lamp, 95% is totally emitted by direct light from the lamp or reflected light from the reflector. You could also say your reflector losses are 5%. Now if you spread your 1100-5% on a surface of 1 square meter, you would irradiate 1045 µmol/m2/s (1045 µmol m-2 s-1). This is called the Photosynthetic Photon Flux Density. If I would move closer to the source and would just light half a square meter the irradiance would be 2090 µmol m-2 s-1. And of course spread over 4 m3 you would get 261 µmol m-2 s-1. Double the surface means half the PPFD. Just divide the PPF by the lit surface in m2 to get close to the calculated PPFD. You will always have some stray light losses (much more with open reflectors!) and you have influence by the reflection of the walls, which causes a loss. PPFD you can easily measure with a quantum meter and a sensor that is specifically designed for the PAR spectrum. Unfortunately real quantum meters are expensive. The Li-Cor meters are used throughout the industry and are recommended. Most meters under $500 use lumens sensors and an internal table to approximate the PPFD in micromoles. We have found them to be inaccurate because they are still more sensitive to certain colors and do not take other colors within the PAR spectrum into equal account.

[Phaeton]

I use the Apogee MQ100, at $300 it does the job well enough. It reads real world output from the source between 400 nm and 660 nm.
Far red and infrared are not represented, still, this is quite a bit more than a lumen sensor. I find it usefull in transfering umol levels from HID to LED to fluorescent. I have red and blue and UVB sensors, the combo gives a pretty complete picture, no single meter does it all, just as one light does not do it all.
The sensor's do not do the work for me, thinking is involved. If I could not read a graph, perhaps I shouldn't be using meters?

Lumen meters read 555 nm green, I don't even own one. If the light looks bright it has green, HID, fluorescent, CMH, tungsten, all of them. Oh yeah, LED growlights are dim, no green, what a coincidence.

Humans see green, it is added extra into all lights to make them brighter, most grow lights add it for eye appeal. Silly, but it works, people buy the bright one.