Re: 420 Consumer Reports Competition - GrowLEDHydro 300w LED vs. 400w HID
TL!
Long time no see, but your timing is impeccable
.
So glad to see you again!
...It seems that 14" seems to be a popular distance to measure LED intensity. Is that some kind of unofficial industry standard?
Likewise, mate! Sorry to hear about your Lowryders. Sometimes, they don't Take It Easy!
Hmmm...well, there is no standard distance to measure intensity in the LED industry as far as I know. Sounds like someone did 'em at that range, and the herd mentality took care of the rest. (Same way we ended up calling 350ma LEDs '1 watt' after Phillips put out some of the first ones at that nominal amperage). Over in Europe they tend to measure in cm/M anyway.
I would like to record intensities at two distances minimum. What would you suggest?
I'll also record intensity at several points along a 30 x 30" grid.
Sounds good, in fact it's similar to what I've done in the past with HIDs, doing it with LEDs would be even better. Reminds me of the light reflector studies George F. Van Patten did in his book
Gardening Indoors with H.I.D. Lights in the 90's, which is how I became a fan of Hydrofarm Sunburst reflectors. Have that text sitting in storage somewhere. (EDIT: found a scanned .pdf of it online now (torrent), will wonders never cease? If anyone wants a copy for reference and can't find it, PM me and I'll see what I can do...)
At this point, it's worth noting that a typical Lambertian LED lens, whether built-in or separate, does not distribute the light evenly over the entire stated angle, but rather tends to emit a majority of it within roughly the center 2/3 of its facing. So if you've got a 90 degree lens, once you get within about 15-20 degrees of the 'edges',
actual intensity starts to fall off pretty quickly.
So mapping it out on a grid like you're planning will be
very useful to look at actual drop-off near the periphery based on height.
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If I was doing a few points, here's what I'd do:
At
minimum, do readings at 1)
12" and 2)
24" high. That's basically 1) Top of your canopy with the fixture 12" over it, and 2) A foot of penetration down from there. If I was going to do a third point, it'd be
36". (So - 1, 2, and 3 feet from the bottom of the fixture). That covers almost all the usable area that we typically care about for growing.
Past that distance, it's not very practical. But for a 30" x 30" grid directly under the light, that'll give you all the info you need. Perfect to figure out the actual light blending that occurs between the individual (clustered) LEDs with a 90 degree lens.
Readings are taken at the top of the light meter of course, so if your meter was 1" deep, hanging the light at 13", 25", and 37" high and putting the meter flush to the floor will give you nigh-perfect readings for 1/2/3 ft.
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When doing the actual grid, didn't know if you had an idea on that yet. I'm a 'keep it simple' kinda guy, so for me it'd be something like this:
1) Get two pieces of large posterboard and tape 'em together
2) Mark the data points at each intersection (crosshairs(+), etc.) with a ruler
3) Call out the readings for each row, while your Lovely and Talented Assistant enters them in the book/laptop for you!
I always prefer closer points if I can get 'em -
but, I'm also not doing the work here. My 'ideal' would be points on a 3" x 3" grid. That'll give you a great idea of the drop-off intensity at the edges when your light's closer to the plants and the garden's not fully illuminated, also.
AND, let's look at how many points we're actually talking about for each distance, based on the grid size:
3" x 3" grid (30" x 30" total) = 100 squares,
121 data points! (11 x 11)
4" x 4" grid (32" x 32" - add 2" to each side so you end on a data point) = 64 squares,
81 data points (9 x 9)
5" x 5" grid (30" x 30") = 36 squares,
49 data points (7 x 7)
6" x 6" grid (30" x 30") = 25 squares,
36 data points (6 x 6)
Multiply that for each distance you're doing.
Now, once you start doing 'em, it'll move pretty quickly - but will take some time.
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Also: while you don't necessarily need readings on a grid for this, personally I'd be interested in at least a
snapshot of the LED hanging at 6" high with the grid underneath it, so as to have a visual representation of the expected coverage of the mid-late flower 'blast-em without bleaching-em' range.
Which is where I'd hang them all the time if I can get away with it...
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Realistically, you can probably do a larger grid (4-5" square) and still get some pretty decent data, the drop-off at the edges will just be a little less clear-cut. Unless you're up for doing 363 data points in the name of Science and Consumer Reporting--!
Hope that helps, SS....
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High Brother Lurker - great to see you back on the boards my friend.
Too bad they don't make a ~325 watt HPS
(My understanding of the 300 LED's draw)
Good thing we have excel to normalize things in the end
I hope you made it to the end of the prior comparison, we did run a bunch of metrics - including your bud to total mass ratio suggestion, which was most interesting.
See you around the boards
Cheers Soniq. Nice to see how much difference that makes in the final biomass numbers. Interesting Is the Word (not Greece
). Excel is the great equalizer there.
I think Mike's site lists 360W for this unit - we'll see if that's on the money. Does make me a little concerned about the thermal management, to be honest. Spent several years in product management for power and electrical distribution components, which gave me a healthy respect for that sort of thing, awhile back...
Regards,
-TL
What he said [Vapoorize] usage could be calculated by measuring line consumption by taking each system in and out of consumption mode [turned on and off] and the current usage measured. You would have to do a D.O.E. but it could be done.
reps to all of you until they stopped me!
)) will get you base level data you can more universally and reliably apply to other situations.
The coolest thread goin out there! Can't miss this one.