So it's not watts per sq ft with LED's?

[REALSTYLES]

I'm like the Winnebago Man but is the Mars Man instead lol. And I feel like a fool defending them it needed to be done. I'm selling the 1600's. they weren't used that long 3 maybe 4 months. I stopped using them as soon as 3 panels made lol. I think I'm gonna go on to the mars thread as soon as someone posts lol. I want to see how they are gonna act hahahaha.

 

[DoctorDelta9]

Like him or not, he did what should be done. I dont even think the light was broken so what was there to fix? He is building his own lights now that are far superior for growing than any MARS panel. Why keep cheap trash around? People who purchase MARS lights and think they are the end all to LED lighting "have no business in the profession" (hobby).

It is ignorant to think that a cheap LED such as MARS is above and beyond other LED (even for the price), let alone tried and true HPS.

To each his own. But it could.of been used for something. Donate it to a medicinal patient, smashing electronics just makes me cringe. Something of value can always be harvested, put in the misc box and used at a later time. And you are correct, hobby not profession

 

[churchhaze]

https://www.rollitup.org/t/smashing-fluorescent-lamps.864130/

 

[REALSTYLES]

To each his own. But it could.of been used for something. Donate it to a medicinal patient, smashing electronics just makes me cringe. Something of value can always be harvested, put in the misc box and used at a later time. And you are correct, hobby not profession

Why would I give someone else a problem. I didn't smash the 1600's they work but mine are better and I'm selling those I paid $593 ea for them but I'm gonna sell them for $400 for people who are still into Disco because it's dead.

 

[silvrsurfer77]

Even then, the uniformity of the light spread will make a big difference. So if your average is 12 PAR W/ft² but there is a big hotspot in the center and dim edges (HPS) then it will decrease the efficacy of the light. The same applies to high powered COBs vs low powered COBs to some extent. And on top of that there are spectral issues that affect the efficacy of the light.

BUT, to the op's question and taking churchs estimation further, approx PAR W of a mars 900 is:

411W - fan power = 400W
400 * .87 driver losses = 348W
348 dissipation W * .25 efficiency = 87 PAR W
87 PAR W = ~426 umol/S (PPF) or 1.22umol/s/ dissipation W
87 * .9 lens losses = 78.3 PAR W

in a 2'X2':
19.6 PAR W/ft²
1026 PPFD average

Ops 30"X30" or 2.5'X2.5'
12.5 PAR W/ft²
655 PPFD average

in a 3'X3'
8.7 PAR W/ft²
456 PPFD average

We may be too generous calling it 25% efficient, especially considering that properly cooled Cree XTEs are around 30%. If there are red leds running hot their output drops off badly. So 25% is probably giving the benefit of the doubt.

How do you calculate PAR W to umol/S (PPF) and how do you get from there to PPFD?

 

[churchhaze]

You need to know the umol/J of that SPD for a 100% efficient source, then you can multiply it by W to get PPF (umol/s). To get average PPFD, divide PPF by the area. The ppfd is obviously higher in the central beams and overlapping areas than the PPFD on the perimeter.

For example, if you have 200W of PAR in a square meter tent and a SPD that has 4.2 umol/J:

PPF = 200W * 4.2umol/W/s = 840umol/s

average PPFD = 840umol/s / 1m^2 = 840umol/s/m^2

 

[churchhaze]

Realistically, 200W of PAR in a 4'x4' could easily be planned out as 200W/16ft^2 = 12.5W/sqft. It works just as well in terms of determining how much light you'll need for just about any of these white leds.

 

[coughphee.connoiseur]

Take the watts dissipated by the leds and multiply it by their efficiency, and you will get PAR watts.

A good rule of thumb is to use 12W/sqft PAR for 2-3 foot plants, 14-18W/sqft PAR for taller.

Very late question but how would one go about determining the efficiency of their light fixture. Of course I'm aware the maker manufacture could possibly provide this information. How accurate it may be I'm unsure but.. just looking into some of the t-5HO fixtures i see no listing of the specific information in the tech specs logistics etc.

I usually on see this technical information listed and provided with top name HID/HPS fixtures and the new wave of COB LED fixtures.

 

[FranJan]

^^^
http://agi32.com/blog/2014/12/10/photometry-and-photosynthesis/

 

[Zulunature]

And here is what I did with my Mars 2 700 bullsh#t W.



And it's a Mars bar now running 4 X CXB 3070 AD 3000K on the Mars drivers @750ma, utilized the heatsinks and plate, wiring, plug, brass hanger points.

This light runs so cool it's incredible a mere 2c more than room temp at the back of the cob.

Used a couple of the drivers on my Gemini CXB3590 72v 3500k CD bin on cutters new passive pin heatsinks.

This one runs not so cool, they ran at 50c heatsink temp in a room temp of 24.5c, however given this is the same as running 36v version @1500ma I'm not unhappy.

I'm thinking of putting a couple of 120mm fans over the Gemini and that will bring the temp of the heatsink back to what I'd like to achieve.


And one of the failed Mars 2 400 lights converts with CXB3070 BB 3500K 125w from wall
is in the attached file.


Realstyles gave growmau inspiration and I in turn had inspiration.


That is a 1600 Mars that's going to be 2 more Mars bars and a few more Gemini lights.

So Mars lights are good for conversions of all sorts as for growing, they will do the job if you throw enough of them at the task at hand. I to fell for the hype they sold but we learn and move on.

 

[MCOB]

Nice grow. Growmau's guides are very in-depth.

So far my understanding of the Mars products like most non COB LEDs is that they suffer light loss with a years worth of use.
Would be interesting to see any of your side by side comparisons of plants grown under CXB vs Mars if you have some.

 

[JoeHam_412]

Anyone know what are what that voltage and the amperage of the mars drivers are??? I guess the question is,how many 36 v cobs can be ran off of each driver??

 

[Zulunature]

Anyone know what are what that voltage and the amperage of the mars drivers are??? I guess the question is,how many 36 v cobs can be ran off of each driver??

Depends on which Mars lights as they seem to have different outputs from reflector type to series 2 type.

My Mars 2 lights seem to have 55-100v drivers @750ma. That's sufficient to run 2 CXB3590 36v or a single CXB3590 72v which I've done both. With the 36v cobs I put 2 per heat sink and converted the heat sink and plate to put it into a bar.



They work very well and I'm impressed with the lower temps can touch directly behind cob on heat sink after 11 hours on and it's cool to touch, yesterday took a thermal IR reading behind the cob was actually 1.5c lower than the room temps.

 

[JoeHam_412]

Depends on which Mars lights as they seem to have different outputs from reflector type to series 2 type.

My Mars 2 lights seem to have 55-100v drivers @750ma. That's sufficient to run 2 CXB3590 36v or a single CXB3590 72v which I've done both. With the 36v cobs I put 2 per heat sink and converted the heat sink and plate to put it into a bar.
View attachment 3671084


They work very well and I'm impressed with the lower temps can touch directly behind cob on heat sink after 11 hours on and it's cool to touch, yesterday took a thermal IR reading behind the cob was actually 1.5c lower than the room temps.

Awesome

Depends on which Mars lights as they seem to have different outputs from reflector type to series 2 type.

My Mars 2 lights seem to have 55-100v drivers @750ma. That's sufficient to run 2 CXB3590 36v or a single CXB3590 72v which I've done both. With the 36v cobs I put 2 per heat sink and converted the heat sink and plate to put it into a bar.
View attachment 3671084


They work very well and I'm impressed with the lower temps can touch directly behind cob on heat sink after 11 hours on and it's cool to touch, yesterday took a thermal IR reading behind the cob was actually 1.5c lower than the room temps.

Thanks, just figuring out what to do whenever mine craps out, lol