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Need help driving 70 1W Cree SMD LEDs

7K views 71 replies 10 participants last post by  Sean W. 
#1 · (Edited)
Hey guys,

I'm going to do it, I'm going to build the ultimate ( but not crazy featured, no lightning and sun up and sun down and no fluffy unicorn effects ) DIY LED light for my 75 gallon, details to come, still in the homework and research phase.

What I need help with is how to power 70 of these Cree 1W LEDs. The ebay listing says they are 1-3W, not sure what that means...

Im going to use:

50x 6000k
10x red
5x green
5x 3000k

I want them to be dimmable, all on one channel. Simple.

Hoping to get the parts off ebay, so if you could provide the ebay listing number, that would be great.

As far as I know, all I need is a driver and a dimmer?

Thanks for any help!

here is the listing for the LEDs im looking at
 
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#2 ·
Watt rating of diodes is kind of a game.. Basically what current they can handle..

Say you have a 3.3 V(f) diode and drive it at 300mA or 900mA.. If it can survive 900 ma it is a "3W" LED.. if not and survives best at 300mA it is a "1W" LED

As 2 drivers and dimmers.. well need the V(f) of your diodes and what you want to run them at.
As to dimmer, manual or not?

If you want to run them at constant voltage it requires terminal resistors..

If you run them constant current you will need to run parallel strings or multiple drivers.. Makes one channel dimming a bit difficult..

How much work do you want to do at modifying ebay parts?

I need to mention, as my standard suggestion, skip green unless you get cyan (or plan on using "just green" for something, you can't "fake" cyan w/ out blue), deep red (660nm) is better than red..

70 x 3.3 (231V so you can't (shouldn't) run all as one string.. x 350mA = 81W

Point is even "simple" has multiple approaches..
Secondly, since you can't run one string, single channel dimming is kind of a waste of technology.
 
#3 ·
Watt rating of diodes is kind of a game.. Basically what current they can handle..

Say you have a 3.3 V(f) diode and drive it at 300mA or 900mA.. If it can survive 900 ma it is a "3W" LED.. if not and survives best at 300mA it is a "1W" LED

As 2 drivers and dimmers.. well need the V(f) of your diodes and what you want to run them at.
As to dimmer, manual or not?

If you want to run them at constant voltage it requires terminal resistors..

If you run them constant current you will need to run parallel strings or multiple drivers.. Makes one channel dimming a bit difficult..

How much work do you want to do at modifying ebay parts?

I need to mention, as my standard suggestion, skip green unless you get cyan (or plan on using "just green" for something, you can't "fake" cyan w/ out blue), deep red (660nm) is better than red..

70 x 3.3 (231V so you can't (shouldn't) run all as one string.. x 350mA = 81W

Jeff, glad youre here to help. Sorry I forgot to post a screenshot of the ebay Leds im planing on using. Not sure if that changes anything from your first post?

 
#4 · (Edited)
I did a DIY LED fixture recently using similar LEDs so I'll share what I learned. First of all I'd suggest a "constant current" LED driver that can handle your load; this gives you a number of advantages including not messing with resistors, power stability and maximum lifespan. To determine the voltage you need, add up the forward voltage for all the LEDs in your array - your proposed setup has 60 at 3.2-3.6V (white and green) and 10 at 2.1-2.4V (red) for a total of 213-240 volts. The next thing to do is decide on your desired power, since these can be run at 350 to 1000 mA that means they can be 1W, 2W or 3W LEDs. Based on that decision you'll end up needing a power supply (or supplies) capable of delivering 70, 140 or 210 watts. However, you don't want to drive your power supply at 100% all the time, so you need one with enough juice that your anticipated load is only 60-80%-ish of capacity. This means you'd need a 100W driver for 70x 1W LEDs rather than just getting a 75W driver and calling it good.

The other option is running multiple drivers. Say you split your array in half with 35 LEDs per driver at 1W each. Now you only need 35W of power and your voltage requirement drops to 110-120 VDC. Plus, if you get multiples of the same driver you should be able to dim them equally with the same dimmer connected to both drivers. I got my drivers from LED Drivers - Phihong, Mean Well, MagTech, LUXdrive & More but I can't find any powerful enough for your application that are dimmable, so you may have to make a couple smaller arrays.

If you use a constant current driver, my advice would be to not run parallel strings off the same supply. Let's say you have two strings of 2W LEDs in parallel each drawing 700 mA. This requires a 1400 mA power supply and everything runs fine, but if you lose an LED in either string, that entire string will shut off and all the current gets dumped through the other one that's still working. Since 1400 mA is way over what the LEDs are rated for, you could basically create a snowballing failure and burn out a bunch of LEDs. I ran all my lights in series and when I lose one the whole array shuts off, but it's easy to pull it out (I used screws instead of glue) and I know none of the other lights will have fried.

I actually registered just to post this so I hope it was helpful :D

Edit: Be very careful about electrical safety when messing with these things. 30V is generally considered the beginning of unsafe voltages for people and you're going to be working well beyond that with currents that are potentially lethal. Not trying to scare anyone out of trying a DIY setup - mine works fantastically and I love it - just don't want to see anyone get hurt.
 
#7 ·
oops sorry guys didnt see these posts, you both must have posted while I was composing my last reply

I did a DIY LED fixture recently using similar LEDs so I'll share what I learned. First of all I'd suggest a "constant current" LED driver that can handle your load; this gives you a number of advantages including not messing with resistors, power stability and maximum lifespan. To determine the voltage you need, add up the forward voltage for all the LEDs in your array - your proposed setup has 60 at 3.2-3.6V (white and green) and 10 at 2.1-2.4V (red) for a total of 213-240 volts. The next thing to do is decide on your desired power, since these can be run at 350 to 1000 mA that means they can be 1W, 2W or 3W LEDs. Based on that decision you'll end up needing a power supply (or supplies) capable of delivering 70, 140 or 210 watts. However, you don't want to drive your power supply at 100% all the time, so you need one with enough juice that your anticipated load is only 60-80%-ish of capacity. This means you'd need a 100W driver for 70x 1W LEDs rather than just getting a 75W driver and calling it good.

The other option is running multiple drivers. Say you split your array in half with 35 LEDs per driver at 1W each. Now you only need 35W of power and your voltage requirement drops to 110-120 VDC. Plus, if you get multiples of the same driver you should be able to dim them equally with the same dimmer connected to both drivers. I got my drivers from LED Drivers - Phihong, Mean Well, MagTech, LUXdrive & More but I can't find any powerful enough for your application that are dimmable, so you may have to make a couple smaller arrays.

If you use a constant current driver, my advice would be to not run parallel strings off the same supply. Let's say you have two strings of 2W LEDs in parallel each drawing 700 mA. This requires a 1400 mA power supply and everything runs fine, but if you lose an LED in either string, that entire string will shut off all the current gets dumped through the other one that's still working. Since 1400 mA is way over what the LEDs are rated for, you could basically create a snowballing failure and burn out a bunch of LEDs. I ran all my lights in series and when I lose one the whole array shuts off, but it's easy to pull it out (I used screws instead of glue) and I know none of the other lights will have fried.

I actually registered just to post this so I hope it was helpful :D

Edit: Be very careful about electrical safety when messing with these things. 30V is generally considered the beginning of unsafe voltages for people and you're going to be working well beyond that with currents that are potentially lethal. Not trying to scare anyone out of trying a DIY setup - mine works fantastically and I love it - just don't want to see anyone get hurt.
Thank you for registering just to post that reply, I really appreciate it!

No, just sort of confirms what I said. do you want to drive the diodes "soft" or hard??
350 or 1000mA..

Ignoring the red and green for a moment..(btw they seem to have 660nm red if you ask) your output is like 55w or 165W..
Without knowing the light out put, im not sure if im going to have to drive them hard or soft. I might end up running them at 350ma to get the desired light output, or I might need to run them at 800+ma to get what I need, Im not sure. Im going to have to build it and adjust the light to my needs.
 
#5 ·
No, just sort of confirms what I said. do you want to drive the diodes "soft" or hard??
350 or 1000mA..

Ignoring the red and green for a moment..(btw they seem to have 660nm red if you ask) your output is like 55w or 165W..
 
#8 ·
I agree that constant current w/ LDD's (some Avail. on the bay) IS the way to go.
But JUST to show you how to "create" a Beamswork Bridgelux type array.
Problem is you can't mix V(f)'s easily.. Would need a separate designed "leg" for like the red:

 
#9 ·
I agree that constant current w/ LDD's (some Avail. on the bay) IS the way to go.
But JUST to show you how to "create" a Beamswork Bridgelux type array.
Problem is you can't mix V(f)'s easily.. Would need a separate designed "leg" for like the red:
I think we both posted at the same time, I want to make sure you saw my other posts jeff?

I guess my question now is there a way of constantly supplying 238+Volts while raising or lowering the amps to control brightness?

-Sean
 
#10 ·
ESt. of your diodes @1W each...no lenses.. 47.5PAR @ 50cm (19.7")


* MIXING LIST
----------------------------------------
Cree XP-E Green (520-535nm) [120°] x5
Cree XP-E Red (620-630nm) [120°] x10
Cree XP-E CoolWhite (5000-10000K) [120°] x50
Cree XP-E WarmWhite (2600-3700K) [120°] x5
----------------------------------------

* SIMULATION DATA
----------------------------------------
Luminous flux : 7,754 lm
Radiant flux : 24,556 mW
PPF : 111 umol/s
TCP : 4760 K
CRI : 98
λp : 633 nm
Color : #FFCEA7
----------------------------------------

* PERFORMANCE @ 50cm
----------------------------------------
Irradiance : 10.4 W/m²/s
Illuminance : 3,291 lx
PPFD : 47.5 umol/m²/s
----------------------------------------

by SPECTRA 1.0β @ 1.023world
SPECTRA
 
#12 ·
Calculator doesn't work that way. but roughly doubling the drive current (2W) should get you close.
2/3.4 =588 mA. Just double the diode count.. ;)
I suspect your pretty set in 1000mA. Just be aware that your heat load will be somewhat problematic. Nothing earth shattering though..
I'd suggest 750mA Ldd-h's for a constant current setup. 1 driver per every 12or 13 diodes..
As I said earlier, dimming gets a bit "complicated' though I did find a manual dimmer w/ both constant voltage pwm and a 5v pwm "port'.
Haven't seen it reail beside alibaba or new zealand.. ;)
 
#13 ·
#14 ·
change your diode count to 72 and run 6 serial rows w/ one ldd per row. 48V power supply @ 5A or more..
Don't see any currently on the bay though. and ldd's are 700mA or 1000mA

Count really isn't crucial,just symmetry.. ;)
W/ constant current you can mix colors
 
#17 ·
You could ditch the reds and replace with full spectrum, then all Vf would all be the same.

LDD's @ 700mA w/3watt emitters would be the way to go.
Plan on 48 volt power supply. LDD's to make up what is needed.
What will you use to supply PWM signal?

70 - 1watt LED's won't get 100 PAR @ 21"

I presently have 80 PAR in a 75 @ 21" with 126watts of LED running @ 87% duty cycle.

If I were wanting a guaranteed 100PAR @ 21" I would estimate 160 watts of LED.
4 quadrants of 39watts would be close enough.
They would not need to be ran at 100% duty cycle this way.
Cooler means they all last longer.
 
#21 ·
Wiring shouldn't be too much trouble IMO if you use automotive primary wire - stuff is rated for a couple hundred volts (600?) and 18Ga will carry over 2A (twice what your LEDs are rated for). Personally I'm shoving 100 VDC at 350mA through 18Ga primary wire and it's holding up fine, but you could step up to 16Ga (carries 3.7A) without too much trouble, it'll just be a little stiffer. The nice thing about a constant current driver is you don't have to worry about jeffkrol's lovely diagram, just hook all the LEDs up in series (pay attention to your + and - because at the voltages we're talking you will blow them if they're backwards) and you should be good to go. Based on what Maryland Guppy said it sounds like you should shoot for the 1000mA driver - with PWM or voltage dimming you can always go less, but if you undersize your driver you can't go bigger without replacing it and the darn things are obnoxiously expensive. I built one 6x2 and two 6x4 arrays and I'm pretty sure the drivers were more than the LEDs. Anyway, the 1000mA driver will give you 3W out of the LEDs for a total of 210W and you'll be able to dial in the duty cycle from there.

As far as spectrum is concerned, I went heavy on the white but also included blues and reds since whites tend to be relatively weak in those specific wavelengths.

And by the way, don't look at your LEDs while they're on. I was testing mine wearing sunglasses and even at only 1W I still saw spots :p

Edit: Oh and make sure to get a good thermal paste, especially with all the heat you'll be generating. Arctic Silver is one of the best and can probably be found at your local PC parts or repair store.
 
#23 ·
To use one power supply for all 70 LEDs you would have to get the 700mA version, giving you 140W of LED power. The 1000mA version doesn't have enough voltage to drive all your LEDs at once so you would need two.

However that driver's bigger brother can do all of your LEDs at 3W no problem (210W of LED power) with capacity to spare. It's the 320W version and has plenty of voltage for the job.
Mean Well HLG-320H-C1050B - Rapid LED
HLG-320H-C-MEAN WELL Switching Power Supply Manufacturer

Personally I found having two arrays convenient since my tank lid is in two halves, so each lid is an independent array. I mounted my heatsinks to the lids though.

To sum up, if you want to use only one power supply yes, bigger power supply and beef cake wiring. Keep in mind there are drawbacks to using power supplies this large, as other people have mentioned, in the safety and potential-for-catastrophic-failure departments.
 
#24 ·
If I were to go with the bigger brother, I would need to be able to dim them, what would be the best solution for this? I envision some kind of knob that I could spin to increase or decrease the light.

a small MS paint diagram would be appreciated to explain where the dimmer goes. I assume on the hot wire before the led array?

youve been such a huge help
 
#25 ·
Amazon driver is $86.46

VS.

48VDC power supply 5A $50 @ evilbay.
6 x $7.50 LDD drivers @ evilbay $45
6 driver LDD board from somewhere $14
Totals $109

So for $25 more you set yourself up way better.

If you bought a 5 driver pre-made board on evilbay $45
Making the total $95
Power supply will adjust up enough to put 14 LED on a driver.
Even a little cheaper @ under $10 more.

What were you going to control this with again, sunrise/sunset?
This can be done anywhere from $20 to $90.

Last time my horse went to water he drank.
Water Horse Plant Fluvial landforms of streams Natural environment
 
#26 ·
If you look on Page 4 of the specifications sheet (second link in previous post) you'll see the dimming information. The B version of those drivers accepts three types of dimming, and for "just turn a knob" operation I have two ideas.

1. Wall-mount style dimming knob or slider:
0-10V Low Voltage Wall Mount Dimming Control

2. Potentiometer (variable resistor), 100k ohm max:
P160KN-0QC15B100K TT Electronics/BI | Potentiometers, Variable Resistors | DigiKey

For either I'd suggest putting them in some sort of box.

Even better, the A version has a potentiometer already built in for dimming (it ships as a "just turn a knob" solution). IMO the choice depends on where your power supply is going to be and how often you see yourself fussing with it. If you want a "set and forget" solution or don't mind accessing the power supply in whatever out of the way place you put it, I think this is the way to go since you can skip the external hardware.
http://www.mouser.com/ProductDetail/Mean-Well/HLG-320H-C1050A/?qs=uP22XH7NdCu2rtoq/B7F1g==

Edit: Maryland Guppy that's a great idea. Wish I had heard about those LDD boards when I was doing my arrays. I've got a couple computer power supplies laying around I would have loved to re-purpose.
 
#27 ·
If you look on Page 4 of the specifications sheet (second link in previous post) you'll see the dimming information. The B version of those drivers accepts three types of dimming, and for "just turn a knob" operation I have two ideas.

1. Wall-mount style dimming knob or slider:
0-10V Low Voltage Wall Mount Dimming Control

2. Potentiometer (variable resistor), 100k ohm max:
P160KN-0QC15B100K TT Electronics/BI | Potentiometers, Variable Resistors | DigiKey

For either I'd suggest putting them in some sort of box.

Even better, the A version has a potentiometer already built in for dimming (it ships as a "just turn a knob" solution). IMO the choice depends on where your power supply is going to be and how often you see yourself fussing with it. If you want a "set and forget" solution or don't mind accessing the power supply in whatever out of the way place you put it, I think this is the way to go since you can skip the external hardware.
http://www.mouser.com/ProductDetail/Mean-Well/HLG-320H-C1050A/?qs=uP22XH7NdCu2rtoq/B7F1g==

Edit: Maryland Guppy that's a great idea. Wish I had heard about those LDD boards when I was doing my arrays. I've got a couple computer power supplies laying around I would have loved to re-purpose.

This sound like a winner. Tell me about this " built in potentiometer "? I envision something that you turn with a small flathead screwdriver on the driver itself. Dial it back on first start up, then turn it up to the desired brightness and then leave it be?
 
#31 ·
Yup that looks like exactly what you're after. Though the version we were talking about only has the current adjuster. If you look at Page 7 of the specifications you can see it in the same place. Found a photo:
https://sc02.alicdn.com/kf/HTB1XB9hOXXXXXaZXVXXq6xXFXXXN/-PowerNex-MeanWell-HLG-320H-C700A-320W.jpg

Looking at the drawings I took notice of the wire sizes. 18Ga 3-conductor on the AC side and 16Ga on the DC. Personally I'd go with 16Ga on the AC and 14Ga on the DC for some inexpensive peace of mind. Again primary wire works great for the DC side and you can cut the female end off an extension cord for the AC side - I found it to be cheaper than actually making your own cord.
 
#36 ·
One thing I would really like to stress, you're working with a lot of power here. To be blunt, it can kill you. The driver needs to be grounded on the AC side (since it has 3 wires), and on the DC side you need to make sure there is no connection between the power for the LEDs and the heatsink. This is especially the case if your soldering is a little messy. I checked the resistance between my heatsink and every connection on my LED array before I ever powered it up. Also, if you ever have to work on your array (replace or move LEDs, whatever) make sure to unplug it and let it sit for a few minutes so the driver can discharge fully. These are of course in addition to normal rules of electrical safety.

Again I'm not trying to scare you or anyone else out of attempting a project like this. But electricity is one of those things that can cause serious harm if you don't show it the proper respect.

With that said the next best piece of advice I can give is to get some automatic wire strippers if you don't have them already. Nothing takes the wind out of your sails like having to strip both ends of a mountain of wires with crimper-style strippers.
 
#42 ·
I used some el cheapo 1W LEDs off ebay (less than a dollar each) and they've been working great for me. Extras are a good idea to have because LEDs can and will spontaneously fail. Honestly though if the lights run as bright as you're intending them to, unless the wavelengths are all wrong I don't see how light will be your limiting factor.

Another suggestion, protect your LEDs from moisture. Either cover the solder joints in silicone or put an acrylic/glass shield in the way, because they will fail if they corrode.
 
#43 ·
I used some el cheapo 1W LEDs off ebay (less than a dollar each) and they've been working great for me. Extras are a good idea to have because LEDs can and will spontaneously fail. Honestly though if the lights run as bright as you're intending them to, unless the wavelengths are all wrong I don't see how light will be your limiting factor.

Another suggestion, protect your LEDs from moisture. Either cover the solder joints in silicone or put an acrylic/glass shield in the way, because they will fail if they corrode.
I dont understand this sentence.

From Jeffs calculations, it looks like I will be running the LEDs around 750ma, a bout 60% of their capacity. Should give me a nice balance between heat, light output, wattage and life span.

One thing I was hoping to add to this build is an inline Current meter. I want to be able to have some kind of LCD readout telling me what current/voltage/wattage the LEDs are running at. Not really sure if that is what its called, but I just typed that into amazon and came across a few products.
something like this?

https://www.amazon.com/Ensupra-Elec...81158729&sr=1-1&keywords=inline+current+meter

EDIT:

oops, forgot to mention, the housing/heatsink I am going to use does have a splash guad, but I was going to cover the solder points with some kind of rubber expoxy something. Havent figured out a solution for this yet, but I wasnt planning on leaving them naked.
 
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