Running "50-watt" LEDs at a 10th of their rating gets amazing results

Edit: There's a grower on this forum doing something with 50-watt LEDs running at 350mA right now!!! Thanks Cinderella Man
https://www.icmag.com/ic/showthread.php?t=301894

this is a couple of threads from another forum I'd like to discuss, the conclusion of these tests seems to be you can get amazing light output with minimal heat using 50-watt LEDs. Has anyone tried anything like this or had similar results? I know a lot of people use those COB LEDs like the Apollo which essentially uses the same kind of LED, just a red and blue variety, and I've heard people complaining about heat and burnout issues. The way these are run in here, during the 150mA tests at least, barely generate heat at all! I'm sure the light output is a bit lower, but the difference between 350mA and 700mA was mostly heat, and even running at 150mA gets you very bright output.

http://lightput.com/forum/viewtopic.php?f=4&t=837

Re: HeatsinkUSA T-Slotted heatsink for high-powered LEDs

by Lightput » Fri Sep 06, 2013 3:12 pm
I got 6 50-watt LEDs, I was supposed to receive a sample of the DMX315 to test this out with, but I don't know what happened to that. These LEDs were rated to run at 1500mA at 25 volts per LED. I only tested them at 350mA and 700mA using 2 of those PXM-703 drivers I've been using, both getting power from the same 48 Volt adapter I've used for previous tests on here.

the 25V per LED these are rated at seemed about right, I could only power one of these per channel using my PXM-703 drivers powered with a 48V DC adapter, which indicates these LEDs need at least around 25V to get going.

I don't know what would have happened if I ran these at the 1500mA like they said these are rated to take, but they get extremely bright and hot at 350mA and 700mA. I do not have equipment to measure light output, but it seemed like the LEDs emitted almost as much light and a little more heat running 700mA than when they were running at 350mA. It seems like the most efficient way to run these would be at 350mA.








The camera was on the same settings for these 2 side by side photos, the sun was not coming directly in but it was a bright day out, also the MakersLED fixture on the ceiling had its 12 white CREE XM-L LEDs at full blast.

The HeatsinkUSA heatsink does an ok job at cooling these off, there's only so much a heatsink can do when you have what is essentially 50 LEDs all crammed into one tiny 50-watt package, these LED's get very very bright. I'm not really sure why these 50-watt LEDs are rated at 1500mA when, from my experiments, they clearly do not need and possibly can not handle that kind of power. Running them that hot might actually have them individually draw the 50-watts they are rated at, but would probably need rediculous cooling to even get a brighter output.

The 50-watt LEDs might have been draining more power than the the 12 CREE XM-L's in the light fixture on the ceiling, which were probably only drawing about 20-watts at the time, but I payed much less for these 50-watt LEDs, and they deffinelty seemed way brighter.

these new 50-watt LEDs are a very bright light source, less efficient than buying all top of the line LEDs, but more efficient than using older very bright light sources like HID lighting. The efficiency of these generic 50-watt LED packages compared to the efficiency of the best of the best CREE LEDs will allow you to save money in the long run by running the more power efficient option, but the cost difference between these LEDs, coupled with the fact that by the time you make your money back in energy savings there will likely be cheaper, more efficient LEDs available, makes the decision a little more difficult to go with really efficient and cheap LEDs or the most efficient and expensive LEDs.


The ability of these 50-watt LED packages to transfer heat to the heatsink kind of sucks. I admit I did not use heatsink compound for this test, but LEDs usually do a pretty good job without thermal compound when screwed down to t-slotted heatsinks like this. The problem was consistant with the HeatsinkUSA and MakersLED heatsinks, The design of the MakersLED heatsink made it so I could only fasten the LED down by 2 of it's mounting holes, but it worked about the same.

I test the heat simply by putting my hand on it and seeing if my hand gets burnt, LEDs usually should run at a temperature below burn your hand hot, but then again, there are 50 actual diodes on each one of these 50-watt LEDs and there is only a thin layer of silicone or something between them and my hand, as opposed to most other LEDs being one diode per package with a much thicker plastic or silicone lens on it, so it's hard to tell if they are too hot, I read somewhere that some of the 100-watt LEDs are meant to run up to 176 F! (80 C it actually said) Doing that will probably give you less light and much more heat than running them cooler, not to mention they will also likely burn out much sooner.

http://lightput.com/forum/viewtopic.php?f=4&t=1041

I used 2 300mA constant current LED drivers (no DMX control) to test how bright the 50-watt LEDs get at 300 and 150 mA. I got these for pretty cheap from Aliexpress, they seem well made and they perform well.


According to the label this LED driver powers 9-12 1-Watt LEDs, but it does a fine job powering a "50-watt" LED, it's powering it much lower than 50 actual watts but it's still really bright. You can even hook 2 up to one of these in a parallel circuit with pretty great results.



These are the same 50-watt LEDs that are rated to run at 1500mA I tested in another thread, I discovered that 350mA seemed to be the optimal current to run these LEDs at. These drivers are only 300mA, but do about as good a job.

The way these LED circuits work, if you have 700mA going into one LED, if you split that signal to two LEDs instead, each LED recieves half of that 700mA (350mA)


The 2 LEDs on the one heatsink are running at 150mA. I should have put them all on the same heatsink for a better comparison.

I decided to see what would happen if I split the signal from one of these 300mA drivers into 2 50-watt LEDs by making a parallel circuit with them. (In the youtube video the parallel circuit is opened and closed, switching the one LED from 150 to 300mA) The results at 150mA were certainly dimmer than at 300mA, but more light was being emitted by splitting the 300mA into 2 LEDs instead of just one. That might be a way to run these new LEDs at optimal efficiency, but you'd need more of them. The heat they give off at 150mA is barely noticable too.

Youtube video
[youtubeif]5WKl9836N6c[/youtubeif]

If my dmx315 ever gets here I'll check these out at 1500mA like it says they are supposed to run at, but I can't imagine it would get that much brighter, they already get really bright at 350mA and almost the same but hotter at 700mA from what I've seen.

note: I got a 96-Volt DC adapter to test these at 1500mA but the dmx315 driver I was waiting on never showed up, in fact, disappeared from the internet as far as I know.

Sorry if I missed it, but was there an actual measure of light output at different power levels?

no, should have invested in some kind of meter. I was kind of hoping somebody with that kind of hardware made a test like this since then. The best that could be done was to use an SLR camera set on manual mode so all the images are taken with the same exact settings, aperture, shutter time, ISO, etc. But no actual scientific readings. I can tell you that is puts off a whole lotta light, can light at least 15ft into the distance at night like its daytime, and puts off so little heat you can barely feel it with 6 of these at 150mA. that's about 36watts max power draw!!

others can chime in, but LEDs have different efficiencies at different voltages. So yes, you could run at a lower voltage and produce more light than at a higher, less efficient voltage.

I think most manufacturers have charts for this.

I agree that you can get good performance from generic COBs by running them soft, although whether it is a better value than the Vero series is a good question.

I tested a few 50W and 100W warm white generic COBs. The 50Watters were straight up defective but the 100W did OK.


Tested with a simple lux meter so they are not perfect for comparing different spectra, just a general guide. I measured the voltage and current of the LED simultaneously and very accurately so that variable has been removed. Here are the results (pulsed measurements at 23C).
$4.37 Vero10 2700K @ 157mA -> 385 lux/W
$10 Generic 3000K "100W" @ 157mA -> 409 lux/W
$2.80 Generic 3000K "50W" @ 157mA -> 158.8 lux/W (dang i want my heatsink back)
$42 CXA3070 3K AB @ 157mA -> 526lux/W (for reference)

We might be able to find the 100W chips for as little as $6. I have some on order to see if they compare to the $10 one I tested "Lohas" from Amazon.com.

Another issue, the generic COBs are mounted on aluminum boards that are warped from stamping, so it makes almost no contact with the heatsink surface unless you take the time to sand it flat. The cooling performance will be very dependent on the thermal compound. If there is a poor thermal interface the heatsink will seem cool because all the heat is trapped in the COB. Another way to say it there will be a very high thermal gradient and very high junction temp. I have stress tested the Veros at 2X max current and they survive while the generics I have done that to die within seconds.

So overall, if you think of the 100W COB as a 20W COB, and run it at 5W, it is not half bad. But the Vero10 does not need to be sanded and it has a lot more red/deep red output.

That sucks about those 50-watt ones you got, it looks like 1/2 the LEDs came pre fried on that one in the picture. I never noticed the heatsink not laying flat on the 50-watt ones I got, I also have them screwed down to a t-slotted heatsink which might straiten then out a bit. That CXA3070 sure is expensive but the results you got from that at 157mA are awesome. Is that higher voltage than the generic ones? Does it run any hotter than the generic ones at 157mA?[FONT=Arial, Helvetica, sans-serif]
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cool info, tnx

Can someone post or post a link to exactly how to DIY build like a 200w led? I am considering building a 200w for my mother cab and two 200w for a flowering cab but don't know where to start. I'm sure I could google it but if anyone has a good recommendation, that would be better. Thanks for posting the info on running these at a lower power and the success rate.

I would recommend getting a nice t-slotted heatsink and getting cheap 50-watt leds from ebay, you can get them for about $5 each, and hooking like 16 of them up in a way that they only get powered at 150-200mA each, the output of that would be at least what a 250-watt MH would do I'm pretty sure, maybe get a mix of cool and warm white. If you take a 700mA constant current driver and hook 4 up in a parallel circuit you would only have to worry about the forward voltage requirements of one of them and they would split the current up evenly so each would be driven at 175mA.

+ _________ _________ __________ __________
========LED===== LED =====LED =====LED
- _________ _________ __________ __________

at 175mA on a nice big heatsink 1 cooling fan would be enough for all them LEDs, unfortunately I can't exactly tell you how many watts that would be or what the lumen output would be, but it'd be good I can tell you that at least.

4 700mA drivers at ~25 each would be about $100
16 50 watt LEDs at about $5 each would be about $80
nice big ol t-slotted heatsink about $100 (at least 2' x 8" I think would be good for that)

If you decide you want more light output, you could always get twice the amount of 700mA drivers and only put 2 LED's in a parallel circuit, making each LED powered at 350mA each, making it twice as bright/hot and probably add 1 or 2 cooling fans to it. These LEDs are rated at 1500mA input but they are really hard to cool like that, and still very bright at 150-200 mA

I'd also recommend getting a some fairly thin pieces of aluminum to mount the drivers to on the backside between the fans, one big piece would work for the 175mA design because that can practically be passively cooled on a nice heatsink, as long as the heat isn't allowed to collect and you have good air flow.

to assemble, mount the drivers on the aluminum sheet and attach it to the top of the heatsink, you could drill holes in the heatsink fins at the edge and the edges of the driver mounting sheet and use good wire ties to fasten it to the heatsink. connect the AC side of the drivers all together any way you want as long as you keep the line and neutral AC wires all together, then connect wires (I recommend a kinda thick, maybe 18-20 gauge, non-stranded wire for easy install and safety) of the DC output of the drivers to the LEDs. positive and negative to 1 50-watt LED, then connect that positive and negative to the positive and negative on the next LED down the line one more time for 350mA, twice more for 230mA, three more times for 175mA untill they are all powered up, then you are good to go, these things are easy to solder, but if the solder doesn't want to adhear to the metal, wipe it clean with rubbing alcohol first then try yo solder it. Don't put up any lights with solder connections that are weak, you should be able to pull on the wires a little bit without the wires coming loose. Taking down lights to fix them is annoying and trying to solder upside down is a huge pain in the ass and kinda dangerous, I'd avoid any of that if possible

to attach wires together, strip the ends a bit, wrap them up really well, get solder all over them to ensure a good connection that will hold under stress, then individually wrap up each connection with electrical tape to prevent against shorts, you can wrap them both up after that if you want

you could also drill holes in the four corners of the heatsink for mounting with a good chain, I wouldn't chince on the mounting hardware, these heatsinks can have kinda sharp edges and can get really heavy.

This setup would only actually draw 70-80 watts of power I think with only the 4 700mA drivers but watts from the wall doesn't necessarily equal light output. Probably THE best way to go for stealth growers.

Also, make sure you get solder with flux in it made for this kind of work, and don't reuse solder you already melted because the flux is probably gone from it. When i first started soldering I got some of this silver bearing solder and that was a giant waste of time.

Thanks OGMolton. Do you think (5) drivers and (15) 50w LEDs would work well at 230ma? The output would be more but how much hotter would it get you think?

The Dopest said:

Can someone post or post a link to exactly how to DIY build like a 200w led? I am considering building a 200w for my mother cab and two 200w for a flowering cab but don't know where to start. I'm sure I could google it but if anyone has a good recommendation, that would be better. Thanks for posting the info on running these at a lower power and the success rate.

Click to expand...

https://www.icmag.com/ic/showthread.php?t=281244

https://www.icmag.com/ic/showthread.php?t=287557

https://www.icmag.com/ic/showthread.php?t=284309

https://www.icmag.com/ic/showthread.php?t=245530


enjoy:friends:

The Dopest said:

Thanks OGMolton. Do you think (5) drivers and (15) 50w LEDs would work well at 230ma? The output would be more but how much hotter would it get you think?

Click to expand...

I've never personally tested 230mA but that sounds like a good plan, 350 mA doesn't even get that hot, but hot enough that 15 or 16 of them on a heatsink would probably need great airflow for cooling, 15 50-watt LEDs powered at 230mA each with good airflow would probably be great. I obsess about LED longevity and I cringe when I see lights like this "768 Watt LED light"

http://www.ebay.com/itm/Apollo-Hort...299?pt=LH_DefaultDomain_0&hash=item2a409c4413

(sorry Apollo, not trying to pick on you in particular, there's lots of these lights with similar designs, I was looking for the grow light that uses EXACTLY those 50-watt diodes I'm talking about but this is close enough)

you can tell by looking at the COBs there they are made with 4 of some kind of 50-watt led COB, if that thing is actually 768 Watts that must be hot as the damn sun or use liquid nitrogen cooling or something. Every "50-watt" LED I've seen has 50 actual diodes like each of these 4 COB LEDs have. 50 diodes in a 5x10 grid, like the 100-watt ones usually have 10 x 10 diodes on them. Those LED's are very likely not going to last 50,000 hours, I'd be surprised if they last 5,000 hours if that they are being powered anywhere near 768 watts

Unfortunately, I'm prohibited from showing what these lights actually do for many bullshit reasons that are out of my control, but I thought I'd share some recent lighting experiments if you are thinking about going down this road.

Also, I think 15 warm white and cool white 50-watt LEDs are a MUCH better idea than this, this is just working with what we got already



This allowed not enough air flow and got too hot

This is the current setup

Unfortunately, I'm prohibited from showing what these lights actually do for many bullshit reasons that are out of my control, but I thought I'd share some recent lighting experiments if you are thinking about going down this road.

Also, I think 15 warm white and cool white LEDs are a better setup than this, this is just working with what we got already

This is an older setup that had to be changed, this allowed not enough air flow and got too hot





This is the current setup

Unfortunately I have nothing to update, but I'd love to see if The Dopest builds that 15 50-watt LED light. That should be a great light.[FONT=Arial, Helvetica, sans-serif]
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Just throwing this out there to see what kind of feedback I get from the led diy pro's. When I found out about the bigger led's (50, 100, 200 watt single's) I started looking around on the web. I found some 50, and 100 watt leds that are made for outdoors. They are made to light up walkways at night. They come in a heat sink, pre-wired, and are weather proof. Would something like that be worth the money? I have the skill set to build one from scratch, just the ease of a pre-fab is real appealing to me.

Here's the link to the fixture I speak of.

http://www.ebay.com/itm/201172462939?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

DoubleTripleOG said:

Just throwing this out there to see what kind of feedback I get from the led diy pro's. When I found out about the bigger led's (50, 100, 200 watt single's) I started looking around on the web. I found some 50, and 100 watt leds that are made for outdoors. They are made to light up walkways at night. They come in a heat sink, pre-wired, and are weather proof. Would something like that be worth the money? I have the skill set to build one from scratch, just the ease of a pre-fab is real appealing to me.

Here's the link to the fixture I speak of.

http://www.ebay.com/itm/201172462939?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Click to expand...

These are cool white. Good for veg (maybe), but not for flowering

Smaller cobs driven at ~ 50% produce less heat (consequently, they will last much longer). Just add more of them to get the coverage you want

Personally, I leave it to the pros, like Amare Technologies, to work out all the hidden issues I couldn't begin to account for.

Plus great warranty