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LED FAQ) Building and DIY
- Thread starter Dion
- Start date
Just wanted to add an interesting observation.
If you go on YT and watch the latest video by Spectrum King, they show some data from measurements of their lights and some other models.
The interesting part is lm/W which is waaaay lower than the calculated output from cxb cobs for example. SC lights xon't even reach 100lm/W except in their new 600W model which is still lower than a medium driven cob. But still SCs seem way better than the other lights*.
I'm pretty amazed to see such poor results, makes me want to test my lights just for fun.
*thing is lumens are still wrong to measure on blurple lights, so no wonder the numbers are so low. There is also a typo in their data, btw. Or maybe there isn't.
If you go on YT and watch the latest video by Spectrum King, they show some data from measurements of their lights and some other models.
The interesting part is lm/W which is waaaay lower than the calculated output from cxb cobs for example. SC lights xon't even reach 100lm/W except in their new 600W model which is still lower than a medium driven cob. But still SCs seem way better than the other lights*.
I'm pretty amazed to see such poor results, makes me want to test my lights just for fun.
*thing is lumens are still wrong to measure on blurple lights, so no wonder the numbers are so low. There is also a typo in their data, btw. Or maybe there isn't.
Dion
Active member
yeah as u know the lumen is pretty bias towards green light blurple tries to miss this range completly
the lumen figures we use to calculate efficency and ppfd off cobs are based of crees minimum output for the bin fyi so you should pretty much always have better than what we calculate
and yeah the spectrum king is total junk
he is taking advantage of the green light bias to try and say his lights produce better par than illumitex(lol) at only 80L per watt?
i use illumitex(just the chips in diy lights) and they are great-honestly fantastic-ofocurse now there are cheaper options so wouldnt buy agian but i love the 10 f1 chips i have
jikko77
Active member
thanks Dion.
to check something i've found recently: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/
"The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ~1500 μmol m-2s-1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2
concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment."
where ~1500 μmol m-2s-1 PPFD is considered the max value usable to grow cannabis sativa
i'm playing as mad scientist here :-D
Such high ppfd needs higher levels of CO2 and a sealed room. I fear with regular CO2 levels the plants would suffer lightburn or another kind of stress.
A sealed room makes heat exhaustion a problem if the lights are not tubed somehow.
Just a thought.
@Dion, those estimates by cree are for minimal output for bins? What can i say? I'm more and more impressed, stoked tbh.
Thanks for the info brother
A sealed room makes heat exhaustion a problem if the lights are not tubed somehow.
Just a thought.
@Dion, those estimates by cree are for minimal output for bins? What can i say? I'm more and more impressed, stoked tbh.
Thanks for the info brother
Dion
Active member
thanks Dion.
to check something i've found recently: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/
"The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ~1500 μmol m-2s-1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2
concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment."
where ~1500 μmol m-2s-1 PPFD is considered the max value usable to grow cannabis sativa
i'm playing as mad scientist here :-D
i have seen that study- you should read the whole thing and see the test conditions
i dont think they are suggesting that 1500ppfd is good, the are saying instead that "The maximum rate of photosynthesis (PN max) was observed at 30 °C and under 1500 μmol m−2s−1 PPFD"
however you should also refer to the graphs to see the rate of transpiration and the negligible increase in photosynthesis under these ideal conditions between 1000 and 1500ppfd and also that photosynthesis continued to increase up to 2000ppfd in 25c but they did not test further(perhaps 3000ppfd at 25c will see higher rates than 1500 at 30c?)
finally this test was done to vegging plants and has no exact link to final yield
in fact anecdotal evidence suggests that yield starts to decrease after 1000ppfd
I would cap it at 1000ppfd and as i stated in the very post of this thread 30c is temp for led growing =D
and and and
further to the point about spectrum king and ppfd in general we have issues with ppl running thier own script codes on the meter to compensate for its inaccurate readings of led lights
then there is another discussion i had on riu with alesh(the guy who derived most of the numbers we crunch for ppfd values)
he is clearly a scientist in the field of lights/physics etc and reckons that the apogee meter is no better than a lux app on ur phone
just saying bro
rant over
jikko77
Active member
@dion i did
the quote of that text was just to sommarize it all.
as i've understood the whole thing is: "about" 1500ppfd is the limit, at 30°c, where you don't see "issue" caused by too much light, the very first thing that come in my mind is albinism, or burns on the leaf, but there is some others. it should be regolated with a particular focus on vpd and the c02 quantity, but that's a my idea.
and your question is something i'm courious about too.
@Koondense, that can be true. is something to think about.
the quote of that text was just to sommarize it all.
as i've understood the whole thing is: "about" 1500ppfd is the limit, at 30°c, where you don't see "issue" caused by too much light, the very first thing that come in my mind is albinism, or burns on the leaf, but there is some others. it should be regolated with a particular focus on vpd and the c02 quantity, but that's a my idea.
and your question is something i'm courious about too.
@Koondense, that can be true. is something to think about.
Hey Gang,
I just purchased two 25-40v @ 1500ma drivers and two cxb3590's (3500k, CD bin, 80CRI, 36v.). My question is what is the longest my wires can be running from the driver to the cob? I am currently wiring each with about 10-12 feet of length, but I haven't finalized anything. I wanted to be sure that wasn't going to be too long and cause some kind of voltage drop due to long distances between the cob and driver.
Any help is appreciated! Thanks much!
I just purchased two 25-40v @ 1500ma drivers and two cxb3590's (3500k, CD bin, 80CRI, 36v.). My question is what is the longest my wires can be running from the driver to the cob? I am currently wiring each with about 10-12 feet of length, but I haven't finalized anything. I wanted to be sure that wasn't going to be too long and cause some kind of voltage drop due to long distances between the cob and driver.
Any help is appreciated! Thanks much!
Voltage drop is not a problem with constant current drivers since the driver will compensate for it.
The current will still be 1500mA even with a very long wire.
Rilla.
jikko77
Active member
Dion
Active member
Indeed
The issue is the drivers having to work harder to deliver that current and voltage, hence they get hot
Meanwell recommends 1.5m max
I think that's enough room to play
tableshaper
New member
I'm debating LED, I have Gavita now but too hot and too low of a ceiling. I question your "THE LONG LIFE DOESNT JUSTIFY THE COST-" where do you see the advancements in LED happening cause I see it in the cobs themselves and you can easily replace a DIY cob. NO?
Roasty McToasty
Member
Ya man, COB LED would be a good fit for you. If you can DIY its not really much more than HID. I have built 3 vero29 rigs for $230 with dimming. Cree cxb3590's are best and more efficient. But they're proud of those. And you'll gain around 3 inches of canopy height over HID. Yes you can replace cobs if they fry. They should last many years if taken care of. Many threads here to help.
I think I have gotten way over my head here.....I started out thinking $200-$300.
And now somehow convinced my self I need to get 3590's to light a 2x2 area.
With the Cree lighting would you say 35 watts per square foot is enough?
Also how many lumens per sq foot in a tent system is enough?
And now somehow convinced my self I need to get 3590's to light a 2x2 area.
With the Cree lighting would you say 35 watts per square foot is enough?
Also how many lumens per sq foot in a tent system is enough?
Hi,
A lot of good work in this thread btw. Will this combination of chips and driver work out ok? I have been looking at this stuff for over a week now and my head is spinning in numbers.
IS the driver too much power for the LED's?
4x cxa3590 77v 1.2a
HLG-240H-C700A
Output Current-Channel 1: 700 mA
Output Voltage-Channel 1: 357 V
Output Power: 249.9 W
Or is this one better.
HLG-240H-C1050A
Output Current-Channel 1: 1.05 A
Output Voltage-Channel 1: 238 V
Output Power: 249.9 W
A lot of good work in this thread btw. Will this combination of chips and driver work out ok? I have been looking at this stuff for over a week now and my head is spinning in numbers.
IS the driver too much power for the LED's?
4x cxa3590 77v 1.2a
HLG-240H-C700A
Output Current-Channel 1: 700 mA
Output Voltage-Channel 1: 357 V
Output Power: 249.9 W
Or is this one better.
HLG-240H-C1050A
Output Current-Channel 1: 1.05 A
Output Voltage-Channel 1: 238 V
Output Power: 249.9 W
Ok I think I have it figured out now? ( sorry can't edit other post )
I can use this one and do 3 38.5v 3590's
HLG-240H-C2100A
Output Current-Channel 1: 2.1 A
Output Voltage-Channel 1: 119 V
Output Power: 249.9 W
or this one and do 3 77v 3590's
HLG-240H-C1050A
Output Current-Channel 1: 1.05 A
Output Voltage-Channel 1: 238 V
Output Power: 249.9 W
I can use this one and do 3 38.5v 3590's
HLG-240H-C2100A
Output Current-Channel 1: 2.1 A
Output Voltage-Channel 1: 119 V
Output Power: 249.9 W
or this one and do 3 77v 3590's
HLG-240H-C1050A
Output Current-Channel 1: 1.05 A
Output Voltage-Channel 1: 238 V
Output Power: 249.9 W
Dion
Active member
Yeah.
I decided to go with the 4 cxa 3590 and the HLG-240H-C1750A
I will turn it down to give me 55% and will get about 7300lm or so each 134 lm/w.
Dion
Active member
It will be much higher than that
U in a 2x2 right?
Around 170-200L per watt and 55-57% eff depending on current
Ppfd close to 1000
I'll crunch the numbers exactly if u like
Sure if you want too. 3 are 10k, one is 9.5k
