I’ve been a little tied up with work lately, so obviously behind getting to this. But the bigger issue is that I’m not exactly sure how to approach this on a level that makes it most helpful for everyone. I would prefer not to take 1000 posts to explain things like ohms law, voltage/current relationships, thermal runaway and stuff like that. Mainly because there’s lots of easily attainable info out there that will probably be able to explain much better than I can. But, this is for you guys. So if we need to hit that stuff, just reach out and say so.
For those of you that have already had these conversations with me, you know I like the meanwell constant current models. Specifically their HLG constant current line. I will be using most of them for examples, but I could and probably will reference some others just for comparison.
I know @MAXHeadRoom could contribute, he’s pretty knowledgeable too.
I’ll be following along @dbrn32. I took an electronics class years ago, so I remember only the basics. Just out of touch from not working with any of it afterwards.
I should brush up on some more technical stuff. I’m just not up on the technological advances since then.
Probably 90% of my knowledge comes from the GrowMau5 videos which of course is available to everyone. You just need to take the time to watch them. I know some of them are very long, but its worth your time.
A great resource for driver selection is LEDGardener. He has a calculator. You just input your lights and it will tell you what driver would be the best. This site also has a good variety of different DIY builds to look at.
Like I kind of touched on in first post, in most cases I’m going to prefer you guys use constant current drivers. That means that the output current (amps, or usually milliamps) will remain constant provided voltage is within nameplate range. These drivers can have dangerous output voltages, but when used in conjunction with series led wiring configurations they remain relatively protected from thermal runaway conditions. In the event of an led failure or wiring error your leds typically just won’t work. Unlike a constant voltage driver with leds connected in parallel, which will have excess current to shove at the rest of your leds.
So, once we get to proper style of driver (constant current in this case) it’s time to get to meat and potatoes. I’ve decided to break these down into two categories. You have your input and output data, and your features.
On the input side, every driver I’ve seen has a range but they do vary. Something like 90-285 vac, which means the driver will work just about the same any time the voltage you can apply an input voltage in that range. Ohms law and the data sheets tell that just about the only difference in day running 120 volts vs 230 volts is the current drawn from your wall. On most models there is also a 1-2% jump in efficiency at high voltage.
On the output side of a constant current driver, you’ll get the output current in milliamperes and the voltage range in which that current level will remain constant. This is probably an important place to point out that most led drivers are sized on the output, but we can talk about that more with driver efficiency. The output voltage range is what you have to work within for your led configuration. Too little and driver won’t fire leds at all, too much and it will regulate output current to a safe level or shut itself down in over voltage protection mode.
Awesome info on all of the growmau5 videos indeed! And the driver selection tool at led gardener is top notch.
I was really hoping to point out all of the basics so that anyone interested could identify what would or wouldn’t work with stuff outside of the charts. They cover all of the big hitters last I checked. But for someone wanting to take advantage of some of the newer strips or possibly some budget drivers that aren’t listed, I think it makes just as much sense for anyone looking to be able to identify what they’re looking at.
So it’s no surprise the meanwell hlg-185h-cxxxx is one of my favorite drivers. It’s the cheapest cost per watt out of the constant current line, and comes through with an impressive 94% efficiency rating when setup properly. Here is a screenshot of the data sheet page 1.
The Cree cxb3590 is one of the most popular cobs for horticulture. So I see fit to use it as our first example. Here is the chart showing it’s forward voltage at different currents.
Using the 36 volt nominal version, you can see that at 1400ma the forward voltage comes in just under 35 vdc. Using power calculation, (35v x 1.4a) you’ll come up with a 49 watt power consumption at that current. We’ll call it 50 watts. So if we want to run those cobs at 50 Watts with this driver, we’ll need the hlg-185h-c1400. If we find the column for that output current, it lists the dc output voltage range from 71-143vdc. In order to find how many 50 watt cxb’s we can run, simply divide the voltages by the forward voltage of the cob. For the minimum (71/35) you’ll see that the number is greater than 2. That means you’ll need a minimum of 3 cobs to meet the minimum voltage requirement of the driver. For the maximum, 143/35, you’ll see that number is just over 4. Since you can’t get a partial cob, that means the maximum amount of 50 watt cxb’s this driver will run is 4. If you’re looking to run less than 3 or more than 4 at that current, you’ll need a different model.
Now take the 1050ma model. Since it’s still a 200 watt driver, the lower output current means the voltage minimum and maximum will change. In order to get to the same amount of power with less current, we need more voltage right? The voltage range on the 1050ma model is 95-190vdc. Using same math you should come up with 3-5 cobs. So you gain a cob, yay right? Not so fast… going back to our power calculation you’ll see these are just a smidge under 40 Watts, like 37. No surprise, four 50 watt cobs or 5 close to 40 watt cobs both equal about 200 watts. There’s just a little more leftover voltage with that led and driver at 1050ma output.
Going down to the 700ma driver, the voltage range is like 143-286. So 5-8 25ish watt cobs.
There are a few things you need to keep in mind when looking at your different options. Most of the connectors that come built in or as part of the cob holders are rated for around 300 volts. Some are higher, but whatever they are you want to be careful not to exceed them. Also, a lot of the drivers will stay in constant current mode a s couple of volts higher than listed. But it’s definitely a crap shoot. All of the voltages listed on led data sheets are “typical” and if you read the fine print, they always give themselves a range. So if you’re calculating for typical (which is normal) and completely fill or go over your available voltage, and get a couple of higher than typical voltage cobs, I’ll have bad news…
Awesome! I thought I was going to be able to get through this a lot faster, and I’m sure there are some things I’ll miss. But I think i can get all of the basic info, and If it helps I’m completely happy doing so.
It helps more than you know! Plus, you can direct people here that have questions so they can hopefully get familiar with some of it and then get confirmation when needed.
So what’s the next lesson, lol. How about one for Quantum Boards, because I’m not biased or anything haha
Quantum boards are a piece of cake, until you start talking about running them in parallel with cv/cc driver. The only real difference with them is the voltage the boards are configured in. Otherwise same as figuring out cobs.
And then you figure out where you want to run them and move forward the same from there. I know the hlg-320h-c1750 will run 3 288’s at around 93 watts per board or the 320h-c2800 will push two all the way to max like 150 Watts per board. The hlg-480h can run up to four a bit harder too. But I was just looking at this with @Onlythebest79, I think you can do same thing for about the same price with two hlg-240’s. Benefits there are safety of lower operating voltage and if you ever ran into a driver failure you’d still have half an operational light.
Another thing to keep in mind, is that these qb’s are really pushing all the rules we thought applied to sizing leds. By that logic, you should have two more boards of identical power in your 3x3. Could you imagine that?
The new boards at 36 volt pretty much fit exactly as the 36 volt cxb above. That was their target, something that cob guys could switch to without having to buy drivers. I haven’t really seen anything with them yet, but I’m going to guess preferred operating currents with them will be around 1050-1400ma. It doesn’t make sense to drop that kind of cash to beat them all the way to max current of 2000ma. 1400ma on a series driver gives you adjustable output from 25-50 watts. 4 boards on hlg-185, 5 boards on hlg-240, and 6 on hlg-320 at that current.
Another 2 boards in there would be blinding lol. More blindier?! Ha. I’m thinking of getting a new board to switch out my 300w Meizhi in the 2x2 and then just use that one for seedlings and clones or for supplemental lighting
