LED Strip Build Questions

Serva said:

You have 2x4ft tent? My suggestion:
2 Panel with 12 Strips powered by HLG-185H-C700A. You can adjust between 190-380W

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I'm finally ready to understand this suggestion (I think...). I think what you must mean is 2 panels with 12 strips each, with each one powered by its own HLG-185-C700A. That would then give me between 200W and 400W (as these are rated at 200W each, and then can be dimmed to half power). Sound right?

For both stages 3500K, for heavier flowering 3000K. I guess I will take half/half running them about two seperate drivers, so I can adjust as my needs are. Also thinking about some cold white light for inspection. Like four 1' strips in 5000K somewhere between running on some seperate driver (350mA, 35W).

Driver questions (this is per fixture -- each fixture is 2ft x 2ft, planning to run 10 strips):

HLG-185H-C700: This would do it, with room for 2 more strips (for a total of 12 per fixture), if I wanted to add some in the future. On the downside, its output voltage range is 143V - 286V, which means I'd need to keep at least 7 strips on to stay above the minimum output voltage of 143V. Maybe that's okay, but I was shooting for something closer to half the strips on for veg. About $49 (US) from Arrow.

HLG-120H-C700: This one is tricky! It's output voltage range is 107V - 215V. The EB strips have a minimum forward voltage of 20.5V, and a "typical" forward voltage of 22.1V. Putting 10 of them on one of these would mean they were all at 21.5V. So they'd turn on; no idea what the implications of running them at just under the typical voltage are as far as brightness and efficiency are concerned. If it's fine, it's better in that I can switch off 5 of them and still be above the 107V minimum output voltage, which is what I had in mind. Of course running all 10 there isn't room for anything else, which is less than ideal, but it seems a compromise has to happen somewhere. $45 from Arrow.

HLG-80H-C700: I could use two of these per fixture, but they're at best $36 each (easier to find at $40), so that bumps the price up quite a bit. Each one could run 4 or 5 strips (but since they can't run 6, I'd have to run 5 on each).

And then there's:

HLG-150H-700: This is a "constant voltage and constant current" driver, and I'm afraid I just don't understand... (Meanwell doesn't make a 150W in the HLG "C" constant current series). Maybe it's an option too; $46 from various places. It's probably at just about the right power for me, so I guess I have to figure this out.

Thanks in advance for any feedback or suggestions.

HLG-120H-C700 will not work, because you have a constant current of 700mA, if the voltage is not enough to power them all, no one will light up.

And in general, you could also take the ELG-100/150/200/240-C700, they are 10$ less expensive.

And I don't know how you grow, so here are just some samples:
- Take a small driver (6 stripes) for vegi, and a bigger one (14 stripes) for flowering. So just the middle part will get light.

An arrangement of the strips could be like: (X = 3000K; O = 4000K)
XXXXXOXOXOOXOXOXXXXX

So you have a middle part 2'x2' (my guess) with lower output, and a higher output for flowering on 2'x4'.

For sure you could also do something like 8/12, or whatever you like.

HLG-120H-C700 will power 9 strips
HLG-185H-C700 will power 12 strips
HLG-240H-C700 will power 16 strips
HLG-320H-C700 will power 19 strips (115USD btw)

I think its easier to go with two driver...

Serva said:

HLG-120H-C700 will not work, because you have a constant current of 700mA, if the voltage is not enough to power them all, no one will light up.

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I definitely don't get it. That driver can output 215V. The minimum forward voltage of an EB strip is 20.5V. So 10 of them in series would require at least 205V. So shouldn't they light up? They can get to 21.5V each... Does the "typical" voltage of 22.1V mean that they might actually need that much to run?

Serva said:

And in general, you could also take the ELG-100/150/200/240-C700, they are 10$ less expensive.

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I looked at the ELGs, and maybe I should again. What I didn't like was that they had no grounding wire. Sitting inside my tent I'm not going to be able to ground the driver -- I can mount it on the aluminum frame for the fixture, but that's not going to be grounded -- just hanging there. So it seems like the HLGs are safer.

algebraist said:

HLG-150H-700: This is a "constant voltage and constant current" driver, and I'm afraid I just don't understand... (Meanwell doesn't make a 150W in the HLG "C" constant current series). Maybe it's an option too; $46 from various places. It's probably at just about the right power for me, so I guess I have to figure this out.

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Okay, there's no such thing as an HLG-150H-700. Sorry about that. I mean the HLG-150H-24. A "constant voltage and constant current" driver, which sounds too good to be true, and probably is. It's "constant current region" is listed as 12V-24V, which is right on -- I need between 20.5V (min) and 24.8V (max) for each strip. But then its "Voltage Adj. Range" is listed as 22V - 27V, so maybe it's only "constant current" up to 24V, but you can adjust it higher (which I wouldn't do...). Then it's 6.3A and can be adjusted down to 3.8A. So maybe I can:

- Wire 10 strips in parallel, set this driver to 22V, and then if I run all 10 I get 630mA through each. If I adjust it all the way down to 3.8A, then I can run just 5 strips at 760mA each.

This sounds promising, but I am remembering a Growmau5 video in which he warns against constant voltage drivers -- which is what I'm thinking this is, essentially, despite the claim that it's both -- I mean, it's constant current, but the current is BIG. So that's no help. I think the problem is that if one the strips blows for some reason, then the others all of a sudden get more current going through them, and that can snowball until you've blown the whole fixture.

Please let me know if I'm making sense...

Yeah, but the voltage is also defined by the current (higher current = lower voltage). With 700mA each strip will need 15,5W to work, that x10 is just a little bit too much.

You already mention the reason why its easier to go with series circuit. Don't know much about it. Was too much for me, to argue around with that. Found all my needs within CCs

algebraist said:

This sounds promising, but I am remembering a Growmau5 video in which he warns against constant voltage drivers -- which is what I'm thinking this is, essentially, despite the claim that it's both -- I mean, it's constant current, but the current is BIG. So that's no help. I think the problem is that if one the strips blows for some reason, then the others all of a sudden get more current going through them, and that can snowball until you've blown the whole fixture.

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The constant voltage/constant current drivers are a better fit for EB (and Sammy) strips than the constant current drivers. At 700ma, the 560mm EB strips can accept voltage between 20.5v - 24.8V, well within the specs for this driver. They can also accept up to 1400ma of current, so there is substantial cushion if one or several strips blow out. I have been running 8 of the 4ft strips in parallel on an HLG-185-48A with no problems. I haven't seen any reports on this forum of cascading failures for any sort of LEDs wired in parallel. To me, the risk is acceptable for the increased flexibility of parallel over series wiring.

Be sure to get the version ending with "A" for the built-in adjustability.

There's also:

LPC-100-700: A 100W constant current driver, plastic (instead of metal) casing. Meanwell doesn't give as much efficiency information as they do for their HLG series, but they describe it as 90% "typical" efficiency. That's very close to the HLGs when they're running on 115V AC, which is the situation here. These I can get for $23 each, so I could run two on each fixture for about the cost of one HLG. They output 72V - 143V, so I can run between 4 and 6 EB strips on each. That sounds pretty close to ideal... Thoughts on this?

Ah, but the LPC-100-700 is not dimmable.

DirtRunner said:

The constant voltage/constant current drivers are a better fit for EB (and Sammy) strips than the constant current drivers. At 700ma, the 560mm EB strips can accept voltage between 20.5v - 24.8V, well within the specs for this driver. They can also accept up to 1400ma of current, so there is substantial cushion if one or several strip blow out.

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Well, cool. I guess I should be thinking harder about these. (Just blew most of a day sitting in front of the computer learning everything I can about drivers, but oh well -- what's another few hours...)

DirtRunner said:

I have been running 8 of the 4ft strips in parallel on an HLG-185-48A with no problems.

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Also cool -- in a 2x4 space? Do you find that to be enough for flowering? Very interested...

And finally:

DirtRunner said:

Be sure to get the version ending with "A" for the built-in adjustability.

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I was thinking of the "B" version and adding my own potentiometer -- somewhere here I read that the built-in adjustment screw is plastic and can be stripped through too much tinkering. It looks like the B version only allows you to control the output current through a potentiometer -- do you know if it still has the built-in voltage adjustment screw? It must, right?

Thanks for all your help.

algebraist said:

Well, cool. I guess I should be thinking harder about these. (Just blew most of a day sitting in front of the computer learning everything I can about drivers, but oh well -- what's another few hours...)

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My bad, I should have jumped in sooner.

algebraist said:

Also cool -- in a 2x4 space? Do you find that to be enough for flowering? Very interested...

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Sorry again. I use the EBs to grow orchids in a 24 sq ft area. They require much less light than cannibus.

algebraist said:

And finally:

I was thinking of the "B" version and adding my own potentiometer -- somewhere here I read that the built-in adjustment screw is plastic and can be stripped through too much tinkering. It looks like the B version only allows you to control the output current through a potentiometer -- do you know if it still has the built-in voltage adjustment screw? It must, right?

Thanks for all your help.

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The screws are metal, but definitely a PITA to adjust. In my grow area, it is more convenient to have the dimming built in to a waterproof package than to have the easy access of the external dimmer. Either way works.

Check these drivers out https://www.cutter.com.au/products.php?cat=ZPE+Drivers

Constant current drivers are fine for running in parallel, just don't exceed the max current. Constant current will act like a voltage limiter as well....since its a diode.

DirtRunner said:

My bad, I should have jumped in sooner.

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No worries -- learning is time well spent. But I better walk away from this computer now while I still have some feeling in my ass... -- back at it tomorrow. Thanks again for your help.

So please, can you explain what is the advantage of parallel over series circuit?

DirtRunner said:

The voltage you quoted is the input voltage (the voltage coming out of the wall socket). The output voltage over which that driver can maintain constant current is 107V ~ 215V, per the data sheet.

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Yup good catch i just cut and paste the wrong spot.

algebraist said:

Yeah, in a series circuit I just have to make sure I stay within the output voltage range -- that's what governs how many I can switch off. And good point -- running it on multiple drivers would make it even more flexible, at the expense of the extra components. (Have to start pricing drivers -- maybe two smaller ones is comparable to one larger one.)

I'm currently thinking 10 2ft Bridgelux EB strips in each 2x2 fixture (2 such fixtures in my 2x4 tent); shooting for being able to switch off about half of them, and everything dimmable. That's about 50,000 lumens total across the two fixtures (I know, lumens for humans..., but what can you do, that's what's easily calculated from the data sheet), and I'm hoping that's plenty for flowering. I was originally planning to only use it for flowering, but I'm on the fence and might want to veg as well -- still working on the whole setup. I'm also thinking either all 3000K strips, or maybe make half of them 3500K.

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Yup thats very similar to what i did. I went with 16 samsung H strips on 2 drivers. The driver i linked is actually the driver i got, each one powering 8 strips for the flexibility you describe. We will have very similar lights.

Serva said:

So please, can you explain what is the advantage of parallel over series circuit?

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Parallel adds current, series adds voltage. I guess being a diode may be inherently better when starting to design, because of current, but I digress.....