DiY LEDs - How to Power Them
- Thread starter SupraSPL
- Start date
rolledupdriver
Well-Known Member
after all this time finally did it!
I'd say things are getting more ghetto in this diy grow, but it works, and temps are holding, so thanks very much for the help guys
I'd say things are getting more ghetto in this diy grow, but it works, and temps are holding, so thanks very much for the help guys
UKpeanuts
Well-Known Member
Something I don't understand about this is that the higher ambient temp shows a reduced voltage for the same current, but I always thought the light output was dependent on current, and as temps fell so did voltage. I've got mixed up somewhere, cann anyone straighten me out?
SupraSPL
Well-Known Member
The Vf of an LED falls as it warms up. The current output of many drivers also falls as the driver temp rises, which in turns reduces the Vf of the COB further. So there are a lot of things interacting. When designing the circuit and picking out a driver, you have to go by the "cold" Vf because it has to be able to start up and stay beneath the maximum voltage range of the driver.
SupraSPL
Well-Known Member
Ya keeping them cool within reason will slightly increase dissipation W, but has several other benefits. It reduces the effect of "temp droop", which is a straight forward loss of efficiency as Tj rises. Blue LEDs and therefore whites are less susceptible to temp droop than other colors, but it can still be significant. You can see that in the Cree PDF, CXA loses about 7% output as the Tj increases from 25C to 85C, and this loss is in addition to losses from current droop. The higher the efficiency of the LED, the more light there is to be gained from reducing temp droop, and the easier/cheaper it is to run them cool.
Running cooler also improves lumen maintenance, so the output of the COB essentially will not fade over time.
Running cooler also improves lumen maintenance, so the output of the COB essentially will not fade over time.
Doer
Well-Known Member
Lately I don't think that's quite it. It's true but, really the heat is a by-product of the quantum electron leakage, is the latest conjecture, (hardly a hypothesis, much less a Theory)The higher temps "stress" the emitter and makes them work harder, just like our plants. I dono the science...just sounded good, right?
We had to solve electron tunneling in CPU chips or we were doomed to go no closer than 50 nm spacing of the circuit paths. Now we are way less than 1/2 of that. It was all about the current. And we know these CPU are high watt devices, so the trick was to make the work happen somewhere else and keep the signal currents very low.
So it seems in LED according to the latest. The higher you drive the current the more you drive electrons off the "road" so to speak. And those electrons can only dissipate as heat, so more goes to heat and less to light the higher the current, is how I am beginning to think about it.
nogod_
Well-Known Member
More or less like a power line. High pressure(amperage) leads to more loss over the line.
So in theory a high voltage low amperage cob might have similar output initially to the same wattage through a low voltage high amperage cob. But over time the high voltage cob is going to degrade slower due to lower current.
This is of course assuming that both cobs are using the same material as a "jacket" to limit leakage.
So why do vero's perform better at higher currents? Do they somehow more effectively limit leakage with increased amperage? I always thought (per stardust) it was because the aluminum chip disperses heat better than a ceramic one.
So in theory a high voltage low amperage cob might have similar output initially to the same wattage through a low voltage high amperage cob. But over time the high voltage cob is going to degrade slower due to lower current.
This is of course assuming that both cobs are using the same material as a "jacket" to limit leakage.
So why do vero's perform better at higher currents? Do they somehow more effectively limit leakage with increased amperage? I always thought (per stardust) it was because the aluminum chip disperses heat better than a ceramic one.
Doer
Well-Known Member
Interesting question and they give the Noble prize for the answer.
And also interesting is they drive those FC Optos at 12a, and they run cool. That's the patent. A different cooling structure at the junction. But, the efficiency is about the amps not the heat and FCO does not compare favorably in the market, Cree Damn it.
nogod_
Well-Known Member
Exactly so fcoptos designed around heat rather than addressing the electron leakage that is killing efficiency.
Electrons that would normally be trapped in the chip and wreak havoc get dumped out the back and through the heatsink. Fix the leakage issue and you dont need to dump the extra heat if you dont create it in the first place.
Anyone else want to see what a 200v, 1amp cob looks like?
Electrons that would normally be trapped in the chip and wreak havoc get dumped out the back and through the heatsink. Fix the leakage issue and you dont need to dump the extra heat if you dont create it in the first place.
Anyone else want to see what a 200v, 1amp cob looks like?
Rahz
Well-Known Member
I'm trying to find a driver to run 4 V29s at 1.4A
I was originally going to run them in series and could use the HLG-240H. There is a high voltage version of this driver but the largest version is HLG-185H-C. It looks like it would be a few volts short. What would happen if I tried to run the 4 vero 29s with that driver?
Assuming it's not possible, are there any alternatives?
Edit: I looked around and apparently there is an HLG-240H-C but it's not listed at Meanwell's US website and apparently not for sale in the US (?)
Can request quote here: http://www.meanwelldirect.co.uk/products/250W-Single-Output-Constant-Current-Dimming-LED-Power-Supply/HLG-240H-CB-Series/default.htm
and here: http://www.sunpower-uk.com/product/250-6W-1400mA-89-179V-IP67-Rated-Constant-Current-Dimmable-LED-Driver/HLG-240H-C1400B/default.htm
I guess I will contact a US distributor and see whether they can be ordered.
I was originally going to run them in series and could use the HLG-240H. There is a high voltage version of this driver but the largest version is HLG-185H-C. It looks like it would be a few volts short. What would happen if I tried to run the 4 vero 29s with that driver?
Assuming it's not possible, are there any alternatives?
Edit: I looked around and apparently there is an HLG-240H-C but it's not listed at Meanwell's US website and apparently not for sale in the US (?)
Can request quote here: http://www.meanwelldirect.co.uk/products/250W-Single-Output-Constant-Current-Dimming-LED-Power-Supply/HLG-240H-CB-Series/default.htm
and here: http://www.sunpower-uk.com/product/250-6W-1400mA-89-179V-IP67-Rated-Constant-Current-Dimmable-LED-Driver/HLG-240H-C1400B/default.htm
I guess I will contact a US distributor and see whether they can be ordered.
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alesh
Well-Known Member
I think it wouldn't run (over voltage protection would kick in). You'd have to dimm it to a current where the sum of Vf's is >= 144V. IDK any driver alternatives, but there's great COB alternative - CXB3070. These are great fit for HLG-185H-C-1400 and even more efficient at 1400mA.
Great find about that MW drivers. I had no idea that they make HLG-240H-C.
UKpeanuts
Well-Known Member
These are brillant, so many flavours to choose from; Have you or anyone else made an order yet? I've sent an enquiry as I'm in europe.
Thanks guys! This forum is ace
Doer
Well-Known Member
Most of the drivers I have seen in the HLG range are internally adjustable.
So, I didn't do the math but, did you account for that?
48v can become 51v. It changes the amps also, of course.
Rahz
Well-Known Member
I can adjust the current down... or I could go with the CXB3070... higher price for more lumens. The lamp is being built for a 2x2' space though.
4 of the Veros @ 1.3-1.35A would be around 24000 lumens. the 4 CXAs would be closer to 30000 lumens. The question is, do I need/want 30000 lumens in a 2x2'?
The other big consideration is that I'm wanting a dimmer knob. If I use the HLG-185H-C1400B -w- Vero29s the lamp will cut off when I max out the knob which isn't very cool.
4 of the Veros @ 1.3-1.35A would be around 24000 lumens. the 4 CXAs would be closer to 30000 lumens. The question is, do I need/want 30000 lumens in a 2x2'?
The other big consideration is that I'm wanting a dimmer knob. If I use the HLG-185H-C1400B -w- Vero29s the lamp will cut off when I max out the knob which isn't very cool.
Rahz
Well-Known Member
Wait, now I'm confused. I'm not electrically inclined and this has been a big learning experience for me. I was thinking that running 4 emitters in parallel would be good because if one of the COBs died the others would continue to shine. But if a COB dies wouldn't that split the voltage between 3 rather than 4, thus putting too many volts through the COBs? Or do the emitters regulate the incoming voltage?
Doer
Well-Known Member
Well, that's a very logically question and it solved by the drivers being a CC type not a CV type. Constant Current is what we need since each tiny element of an emitter, hundreds of them, in some cases, with each have it's own voltage at the set current. With a constant current, balanced at the driver, they can all produce a balanced light output. The volts float slightly.
So, you can run drivers and COBs in both parallel and series at the same time. You can divide up enough volts to go around and add up a current to hold constant.
Greengenes707
Well-Known Member
Parallel is a no no for cobs. Both Cree and bridgelux specifically say not to do it. There is too much voltage variation from cob to cob that current hogging could happen.
So just run them in series...top cobs are amazing, and you won't hve to worry about failure as long as the build is to "code".
I have put 4 CXA's on a hlg185. It is hard capped at 143v. The cobs pull too many volts so the driver corrects down to below 1000ma(960ma). And is basically worthless.
That is why I like the changes to CXB's so much...they allow us to use all of the hlg185's potential.
I have sample coming from LSD power. So ill let everyone know. But t their 200w version(same as hlg185) is not dimmable...so that sucks. But their 150 and down are. I have the 150s coming to run 3 in series.
Hope that helps
So just run them in series...top cobs are amazing, and you won't hve to worry about failure as long as the build is to "code".
I have put 4 CXA's on a hlg185. It is hard capped at 143v. The cobs pull too many volts so the driver corrects down to below 1000ma(960ma). And is basically worthless.
That is why I like the changes to CXB's so much...they allow us to use all of the hlg185's potential.
I have sample coming from LSD power. So ill let everyone know. But t their 200w version(same as hlg185) is not dimmable...so that sucks. But their 150 and down are. I have the 150s coming to run 3 in series.
Hope that helps