Cree PAR38 LED spotlight.

[ALToronto]

Originally Posted by Kino

Hello there, I am a neo-phyte with my lighting needs. I think I will need LED bulb(s) and would like to clamp them on to my rack. Just wondering, if I do not wish to use reflectors, what would you folks recommend for mounting? Thank you for helping out a newbie!

Did you read the rest of this thread? We're talking about regular screw-in lightbulbs that replace old incandescents. Get any fixture you like, yard sales are a good source.

[This Side of Paradise]

Anyone taking par rating and comparing the to actual wattage used? I've been using diy cree fixtures for several years now and I've dabbled with the cheaper aliexpress with so called bridge lux or epistar leds and the par to watt has always been lower even lower than my standard t5s.

[ALToronto]

Originally Posted by This Side of Paradise

Anyone taking par rating and comparing the to actual wattage used? I've been using diy cree fixtures for several years now and I've dabbled with the cheaper aliexpress with so called bridge lux or epistar leds and the par to watt has always been lower even lower than my standard t5s.

It's not just the overall light output, it's the spectral profile of the lights. But with a crude light meter phone app, I compared the light output of a 23 W daylight cfl and a 12 W LED bulb, also 6500K, and they were similar at the same distance. My 22 W LED bulbs are aimed only at catts, from a much larger angle (and therefore distance) than my few remaining cfl's and lower power LED's.

I have no complaints about the Epistar / Bridgelux 5W chips I put together for my living wall. But yes, we've had many discussions in other threads about which diodes are better. Regardless of total light output, I will never go back to fluorescents. LEDs perform better in the wavelengths plants need. Best

[This Side of Paradise]

Actual draw at the plug is something most don't review. You can power 5w at many different amperage. It's too bad many led manufacturer s don't supply all the need info.

[ALToronto]

Originally Posted by This Side of Paradise

Actual draw at the plug is something most don't review. You can power 5w at many different amperage. It's too bad many led manufacturer s don't supply all the need info.

How do we measure the draw at the plug?

---------- Post added at 01:30 PM ---------- Previous post was at 01:10 PM ----------

You also need to consider the longevity of the lights themselves. Fluorescents degrade in light output much faster than LEDs, necessitating more frequent replacement. Now that the actual price of the LEDs is comparable to that of fluorescents, the frequency of replacement must factor into the economic equation. Add to this the disposal issue - all fluorescents contain mercury vapour, and must be disposed of as hazardous material, and there is simply no comparison.

On a related note, I just replaced some high bay lights in my plant. I had HOT5's, each fixture with three 4' tubes, drawing approx. 75W per fixture. My workers had to use additional portable lights to see what they were doing, and the tubes were replaced only 3 months prior. We put in 150 W LED fixtures, two units so far to replace 3 fluorescent fixtures. It's as if someone removed the roof and let the sun shine in. I bought four units, and I may end up selling one or two of them. Here's a photo in case someone is interested.

[This Side of Paradise]

One easy way is to use a meter(kill a watt is one brand name) that you just plug the unit into.
Altoronto if you want to borrow mine you are welcome to, my guess is you in the Toronto area

[Tschimm]

Hey Al. This fixture looks great !
I would buy one if there wasn't that much water between us :-)

Could you post a picture of the fixture in action ?

[ALToronto]

Originally Posted by Tschimm

Hey Al. This fixture looks great !
I would buy one if there wasn't that much water between us :-)

Could you post a picture of the fixture in action ?

I tried, but there is no way to get anything other than a screen full of white. They're 6 m from the floor, and you simply cannot look up without getting completely blinded. Fortunately, the lenses are very focused, so even from a 30 deg angle, it's more tolerable. My employees are talking about needing sunglasses.

[naoki]

Originally Posted by This Side of Paradise

Anyone taking par rating and comparing the to actual wattage used? I've been using diy cree fixtures for several years now and I've dabbled with the cheaper aliexpress with so called bridge lux or epistar leds and the par to watt has always been lower even lower than my standard t5s.

I agree with you, I'm not going to waste money on those cheaper LEDs (I guess lots of people will go through this because of the attractive price). Here is a thread to compare Cree vs eBay (message #18). In the thread I used a fc meter. Note that light meter I used in the thread gives lower reading with artificial light than the cheap light meter which several people are using for plants. So the absolute value there isn't be used. I now have a Li-COR Quantum sensor, and I haven't posted the data yet, but the efficiency of the eBay LED (epi* etc) is pretty disappointing even with PPFD measurement. They are amazingly cheap, but it costs more money than Cree or (real) Bridgelux within a couple years according to my calculation.

I'm sure the quality (efficiency) of those cheap LEDs will eventually goes up by imitating the more modern technology. But at this moment, it is better to stick with the top brand (Cree, Bridgelux, Citizen, Samson, Seoul Semiconductor, Philips etc) for people who doesn't want spend lots of money for electricity. They still keep making large improvement (e.g. there was a recent announcement of 10% increase in the efficiency of Vero series a couple weeks ago).

[This Side of Paradise]

Currently I'm test my new 40 cree xm-l2 fixture driven at 1750 MA supplemented with 28 660nm, I'll a quantom meter on that to see how it does. So far I've been very pleased with my other diy cree builds.