LED Strip Build Questions

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 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.

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In all reality, runaway is being very limited by our overkill on heatsinking. Even when selling these diodes for other commercial purposes, they are advertising a 85C Tj-c.....and we mostly don't do that. So really even though most squawk about runaway which in reality is mostly true, we never take into account thermal load, which runaway requires far more than we are feeding, like Tj-c temps of 135c.
Thats my take on it.

Abiqua said:

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.....

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And at which point should i take a constant current, or a constant voltage driver? I still don't understand what the benefits are from each one...

You sorta did things backwards, you bought 20 strips just cause 20 was a round number i guess and are now trying to make a driver fit them. Reality is no driver is going to fit 20 strips exactly right. If i was you id get two HLG-120H-C700 with 9 on each. Then i'd get another driver for just the other two as my veg light. Thats if i just had to use all 20 strips like you seem to want to.

Serva said:

And at which point should i take a constant current, or a constant voltage driver? I still don't understand what the benefits are from each one...

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These are the basics, maybe you should read up on parallel wiring and series wiring, before you fry your shit. Ever wire up a sound system for a car?
Again, parallel adds current to each circuit and series adds voltage. Both can be used simultaneously as well.
If you don't understand the circuit, I can't explain further.

I understand the circuit, and I understand how to calculate. I just want to know what the practical advantage is of each kind. Like someone mentioned "flexibility" for parallel circuit... actually I could run my setup each way, math will tell me the same for both, if I go 2p6s at 700mA, 12 all in series at 350mA, or 12 in parallel circuit with 4,2A.

Serva said:

I understand the circuit, and I understand how to calculate. I just want to know what the practical advantage is of each kind. Like someone mentioned "flexibility" for parallel circuit... actually I could run my setup each way, math will tell me the same for both, if I go 2p6s at 700mA or 12 all in series at 350mA.

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Either works fine. For a noob like me, parallel was easier for exploring design options.

EB strips were my first venture into LED lighting. I had to order the strips and driver before I was exactly sure how many strips I would need, how to arrange them for an even spread and the current at which to run them. Parallel made trying different configurations very easy. EB strips have a very wide tolerance for varying the current (200ma min. to 1400ma max, a factor of 7x). Voltage latitude is much tighter (20.5v min to 26.1v max, a factor of 1.27x). I could add or subtract strips all day long without worrying about whether I was exceeding power specs using parallel. I could have done exactly the same thing with a constant current driver and serial wiring, it would just take a bit more certainty about what the final design would be to ensure I was buying the right driver.

Im like dirt, this was new to me but the mistake you made was ordering your strips before you had it matched to what driver/s you were going to use and what wiring. Now you have the basic understanding of figuring out what will and wont work.

Again tho if it was me i'd stop worrying about trying to jam 20 strips into a configuration that is never going to be optimal. Use 18 of them and the other two are a start to whatever veg light you want to build, its how id do it. Even if yuo arent interested in a veg light and never use the others, its a under $20 mistake.

The thing is tho it depends what your goal for your light is. Before my drivers were ordered i had it decided i wanted to run my strips at 700mA. The reason i decided on that was because i wanted to run them as bright as possible per strip while not getting too hot to have to worry about a major heatsink. I wasnt worried about maximizing the efficacy of each strip, was more concentrating on getting the most light i could for budget without creating too much heat to deal with so CC was a better option for my specific uses.

The kind of situation where you see guys wanting to run parralell its usually people whos end goal they are chasing is making their light as efficient as possible. You see it more in cob builders because if they run it parellel with a constant voltage driver over time they can keep adding more cobs to the circiut and it just lowers the current going thru each cob so over time their light becomes more and more efficient.


Either CC or CV or paralell or series will work, it just depends what you are trying to do with your build. There is no cookie cutter "this is the best" answer for every build.

That make some sense to you what i mean?

haze010 said:

You sorta did things backwards, you bought 20 strips just cause 20 was a round number i guess and are now trying to make a driver fit them. Reality is no driver is going to fit 20 strips exactly right. If i was you id get two HLG-120H-C700 with 9 on each. Then i'd get another driver for just the other two as my veg light. Thats if i just had to use all 20 strips like you seem to want to.

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I haven't bought them. I picked 20 because that gives me 50,000 lumens (really 21 would be closer, but you can't split 21 across 2 lights). 50,000 lumens is the round number, but I didn't make it up -- found it somewhere...

In any case, I've been thinking 18 on two HLG-120H-C700s is probably the way to go. I do want the flexibility to veg as well, but after thinking about it overnight it makes no sense to "switch off" strips to do that -- the driver can power half as many strips, or it can run all the strips at half current. Since the strips are there anyway, it makes more sense to run them at half current -- simpler design, which is always good, and the strips run more efficiently (but the driver runs less efficiently -- not sure how those two add up, but I'd rather call it a wash than obsess about it).

Which brings me to: Is 9 strips (per 2x2 fixture) run at half power too much for veg? If so, then I guess I need a dedicated veg light. (I could just keep these higher above the canopy, but that's a real waste of energy).

Just to see if I really get it: The HLG-120H-C700 has an output voltage of between 107V and 215V. So it can power between 5 and 9 EB strips (at 22.1V each). I think I could run just 5 strips on it for veg, and still be able to dim it to half current, so I'd be running 5 strips at 350mA. But now I'd be effectively running the driver at something like 25% or 30% of its capacity, which would lower its efficiency to something like 87% (looking at the graph on the driver's datasheet), compared to the 91% - 92% it gets at half or full capacity. Sound reasonable?

In any case, I just ordered two HLG-120H-C700-B drivers from Arrow, and 18 of the 22 inch, 3000K EB strips from DigiKey. Time to start searching for aluminum...

algebraist said:

In any case, I just ordered two HLG-120H-C700-B drivers from Arrow, and 18 of the 22 inch, 3000K EB strips from DigiKey. Time to start searching for aluminum...

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Btw, I have found the series cc mean well driver run at less than the published voltage. It would be interesting to see how few strips it would power up and run reliably.

BuddyColas said:

Btw, I have found the series cc mean well driver run at less than the published voltage. It would be interesting to see how few strips it would power up and run reliably.

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I have the B series CC ones and are rated to pull 150watts. Before i had a pot soldered in i had a borrowed killawatt and it was pulling 168 from the wall. It was higher than it was rated for me. Havent had the killawatt here since i put the pot on it tho.

haze010 said:

I have the B series CC ones and are rated to pull 150watts. Before i had a pot soldered in i had a borrowed killawatt and it was pulling 168 from the wall. It was higher than it was rated for me. Havent had the killawatt here since i put the pot on it tho.

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Yes, no pot on a b series gives you a few percent "bonus" watts!

BuddyColas said:

Btw, I have found the series cc mean well driver run at less than the published voltage. It would be interesting to see how few strips it would power up and run reliably.

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Nice -- thanks for the tip. Maybe I'll experiment...

Still hoping someone will comment on post #69 (dude...). Heading out of town until Tuesday, so I'll be offline until then, but looking forward to checking in.

As far as post 69

if you search for eb veg light you will see descriptions of what others have built for a veg light.

It depends on what your space is and what you want to do if you want a specific veg light or just use dimmer on your flower light and turn it way down. Many have seperate veg and flower spaces so they always have something flowering, and always have some clones or seeds vegging out so right after chop theres already vegged out plants ready to flower.

If you go with a seperate veg light you'd want a different driver than that 120 - 700 one. If you go a seperate veg light just use search for eb veg light and it will help you find the ones described in that thread to use for ideas. If memory serves right most of them have the strips running 350mA or 500mA for veg, and color temp wise from 3k all the way up to 5k.

Plenty of ppl just dim down whatever they use to flower though, it will do the job just fine.

If you have the space ect id go seperate veg area and flower area as you will have much more frequent harvests. Depends on your needs and goals really. There is never any perfect answer its what is best for you.

Personally i generally dont even consider efficiency much, its not like i have a warehouse sized space with a 4 or 5 figure electric bill. Then id definately be going for efficiency, but for me an extra $20 on the power bill makes no difference.

For the record, I think I have found that the HLG-120H-C700 will not power 9 of the 22 inch EB strips. Although the driver is rated to 215V and the strips are rated as having a "typical" voltage of 22.1V at 700mA (and 9 x 22.1 = 198.9), that's at 50 degrees Celsius, which is pretty hot. They undoubtedly heat up to that easily, but the driver has to be able to power them when they start up cold, which could be more like 18 degrees C (about 65 F). The data sheet for the strips isn't specific enough to predict the required voltage at that temperature, but the driver can't handle more than 23.89 V per strip (which is 215 / 9). Based on the troubles I've been having, I'm guessing the requirements are somewhere right around there. (Please take a look at my post "Bad EB Strip?" for details about what's been going wrong: http://rollitup.org/t/bad-eb-strip.942178/)

I should have paid more attention to:

BuddyColas said:

Btw, I have found the series cc mean well driver run at less than the published voltage.

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Maybe that's what's going on. In any case, I am thinking I have to rebuild with 8 strips per light.

Can't you just disconnect one strip and test before "rebuilding"?

Yeah. But I have one panel with 9 strips working fine, and the other with the 9th strip failing. I don't expect any problems if I remove a strip from the working one, and if I remove the failing strip from the panel giving me trouble, I expect that to work fine as well -- my only two theories for what's going wrong are:

1) the replacement strip is also bad, or

2) the driver can't power all 9 strips.

Both of those situations have the panels working fine with 8 strips, so I'm not worried about testing before reconfiguring. I will anyway -- you're right, why not. But I expect that to be a minute's work, and then I'm drilling new holes.

In case anyone cares to chime in, it seems more likely to me that it's the second possibility -- underpowered driver for 9 strips. But I'd have expected that if the strips needed, say, 217 volts and the driver could only manage 215V, then they simply wouldn't turn on, not that 8 of them would and the 9th would get damaged. Does that make any sense to anyone?

If the volts are not enough, why would it damage the strips? Maybe someone can clarify this. Because I thought, if its just too less, they wouldn't light up at all? Isn't there a growmau5 video demonstrating it with sponges?

Serva said:

If the volts are not enough, why would it damage the strips? Maybe someone can clarify this. Because I thought, if its just too less, they wouldn't light up at all? Isn't there a growmau5 video demonstrating it with sponges?

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That is my understanding.....
I have 8 x56omm EB strips running on a MW185 1050, data sheet has the Vf at 190, never tried to add a 9th strip, I just assume as mentioned above none would light up, don't think it can damage anything....

On the other end of the equation, I have had a driver go into "hiccup" mode. I tried to run a single cob on a MW ELG driver alone....WAY overvolted, flashed like a strobe light until I added more cobs, didn't do any damage.....