# Chinese 10W LED vs Chinese 5050SMD's.



## mach_six (Sep 12, 2005)

Did you consider using thsoe 10W LED flood lights? 

What GPU cooler is that for? Looks even bigger than the one on my Phenom X6. I only used the stock one.

I have a 5x1W LED screw in bulb, the heatsink on it doens't seem adequate because i burned myself, I can only imagine how hot a 10W gets.


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## Naekuh (Oct 19, 2011)

mach_six said:


> Did you consider using thsoe 10W LED flood lights?
> 
> What GPU cooler is that for? Looks even bigger than the one on my Phenom X6. I only used the stock one.
> 
> I have a 5x1W LED screw in bulb, the heatsink on it doens't seem adequate because i burned myself, I can only imagine how hot a 10W gets.


its the zalman one with heat pipes... i forget the model number.

Didnt want to use the flood lights because part of the fun for me in this is the actual building! 

Currently im still playing around with them.. the LED's dont even require a solder because u can use 16-14AWG disconnect pairs to tie them. 

Im also playing arround with PC fan controllers by sunbeam to use it as a dial so i can dim the LED's @ will. 

LED's are so much fun. 


But yeah.. i can totally see why people use 3W LED's instead of these 10W's. 

They really burn HOT.


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## redfishsc (Aug 29, 2010)

Nice comparison. 

The big LEDs can really be useful as long as you don't mind the occasional shadow, or if you can find an optic that will allow you to raise it up high to make shadows smaller without losing intensity.


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## Naekuh (Oct 19, 2011)

some updates... i decided to wire up the 2nd 10W LED. 

My fish are thinking there are 2 suns.... 










This is how you can also wire these guys up without soldering...









Im using my own thermal adhesive  basically add a tiny drop of super glue to your favorate thermal paste blob. 










As you can see i tied them to a fan controller, so i can dim them via voltage. 

Ummm should i toss the third 10W on the 10gal?  
I think my fish would go blind then no?  

Its pretty fun to play with.... now i need to wait for the cree's, but i figure 4 of them are required to = 12V and 12V in LED's should be more efficient then 10W single 12V led.


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## Jeffww (Aug 6, 2010)

That's badass. What's your rig right now?


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## Naekuh (Oct 19, 2011)

Jeffww said:


> That's badass. What's your rig right now?


a 29 gallon which i took apart, and that i will rebuild once i get everything i need down. 
Right that that 10 gallon is my Toy tank.. to see what works and what doesnt... a quick burn down lesson in a sense b4 i step up to a larger vol. tank. 

lol... i am trying to get back into the game with the new tech, also meshing what i learned in PC moding to the actual fish tank.

Funny eh? 

one expensive hobby to another at least its not cars again... :\


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## Jeffww (Aug 6, 2010)

Naekuh said:


> a 29 gallon which i took apart, and that i will rebuild once i get everything i need down.
> Right that that 10 gallon is my Toy tank.. to see what works and what doesnt... a quick burn down lesson in a sense b4 i step up to a larger vol. tank.
> 
> lol... i am trying to get back into the game with the new tech, also meshing what i learned in PC moding to the actual fish tank.
> ...


I meant your pc lol.


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## HolyAngel (Oct 18, 2010)

This is awesome! 
Its also something I've been thinking of doing since i work at a pc repair/recycling place and have TONS of power adapters.. 

Can you explain how you wired in the fan controller to dim the LEDs?


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## Naekuh (Oct 19, 2011)

HolyAngel said:


> This is awesome!
> Its also something I've been thinking of doing since i work at a pc repair/recycling place and have TONS of power adapters..
> 
> Can you explain how you wired in the fan controller to dim the LEDs?


Let me know if u dont know how to jump start an ATX PSU. 
Its fairly easy by crossing the green wire with a black ground wire, and u can make that ATX PSU work via switch on the rear. 


Basically a fan controller handles voltage. They are basically pots.. or rheostats which limit voltage. 

You need to make sure first off the fan controller can supply the amps per channel. The Sunbeam is a great controller for the price. 

Now a fan has 3 headers on it. 
Black Red, and Yellow. 

The black is the -, the red +, and the yellow is an RPM sense header. 

You can buy fan headers at any PC accessory store, or fan header extenders and just splice the ends together.
http://www.jab-tech.com/12-3-pin-extension-cable-FC33-12-pr-1614.html

Then plug the new fan header into the fan controller, and use it as a dial. 

If you want pictures i can take some and show you.


Just note, if your going to use something higher then a 10W LED, like a 20W LED, it wont work unless its 12V. 
PC's just happen to follow cars in the 12V rule, so PC accessories will work with 12V LED's. 

Or you can just serial wireup 4 3W Led's so they = 12V, and control all 4 via 1 dial. 

The sunbeam controller $14.00 :
http://www.jab-tech.com/Sunbeam-5-1-4-Rheobus-Kit-BLACK-pr-2530.html

Specifications

1. Power : 20 watt per channel
2. Input voltage : DC 12V
3. Output voltage: 0 ~ 12 V
4. Output current: up to 1.67 A
5. Dim: 148.5x 105x 42 mm
6. Weight( Net) : 184 

Can handle up to 1.67A / channel, which means easily a 10W x 2 Led on 1 port as long as they dont draw more then 800mA each.

The ones im using can draw up to 1amp @ 12V ~ 12W LED and not really a 10W LED...

i should tie them to my multimeter and find out if the spec's are true or not :\

Updates:

3 x 10W LED's :O my fish are gonna need sun glasses









how its wired:









and all 3 dim'd.


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## HolyAngel (Oct 18, 2010)

Sweet! Thanks for the write up


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## Naekuh (Oct 19, 2011)

took better pictures of 3 on full blast:









yeah they are gonna go blind... :\


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## freph (Apr 4, 2011)

Hurts my eyes just looking at the lights lol. LEDs are crazy bright. Awesome setup, though.  Any thoughts on a shroud/fixture to contain the lights?


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## Naekuh (Oct 19, 2011)

freph said:


> Hurts my eyes just looking at the lights lol. LEDs are crazy bright. Awesome setup, though.  Any thoughts on a shroud/fixture to contain the lights?


hoppy has a thread where he is using PVC as a support to hang the sink on top of the tank.

i think i am going to go though that route, with this sink supported by pvc.... 

http://www.rapidled.com/servlet/the-82/4.25"-x-23"-Aluminum/Detail










still waiting for the cree's


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## HolyAngel (Oct 18, 2010)

so wait, are you using a psu AND that power adapter to power these or can you just use a standard psu? I know the fan controller takes a 12v standard molex connecter but you originally showed that power adapter.. If i can just use a atx psu to a fan controller and then the led's that makes it super easy.. Otherwise if you need both i'm slightly confused on the wiring..


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## Naekuh (Oct 19, 2011)

HolyAngel said:


> so wait, are you using a psu AND that power adapter to power these or can you just use a standard psu? I know the fan controller takes a 12v standard molex connecter but you originally showed that power adapter.. If i can just use a atx psu to a fan controller and then the led's that makes it super easy.. Otherwise if you need both i'm slightly confused on the wiring..


no that adapter i linked has a PC molex head as part of the adapter. 
I use them on my watercooling pumps and LED's to test them b4 i tie them up to a real PSU. 

lol. 

If you have a regular PSU, you can use that, its basically the 12V rail you want from a PC PSU. 

The PC PSU has 2 rails.. a 12V rail, and a 5V rail. 
The 12V rail is typically the Yellow wire with the black wire next to it.


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## HolyAngel (Oct 18, 2010)

ok thanks for the clarification ^^

I know all about pc equipment as i've been working on them since i was a little kid and do it for a living now, but that'll make sure everyone else understands too, thanks! 

Now to hunt down some of these leds and have some fun myself


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## Naekuh (Oct 19, 2011)

Red 3W LED's x 4 in serial wireup. 660nm range. 










I was thinking it would give me a lot more red hue, but the 10W x 3 over powers it to almost nothing..












now lets see if i can get that test batch of HC's to explode... 
The anibus Nana is going crazy right now... lol... ive never seen an anubis grow so fast b4.


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## HolyAngel (Oct 18, 2010)

Wow, the color with all of them does look nice though.. Any idea on PAR with this setup? Are you using co2?


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## Naekuh (Oct 19, 2011)

HolyAngel said:


> Wow, the color with all of them does look nice though.. Any idea on PAR with this setup? Are you using co2?


no par meter... and yes i am injecting CO2... u can see the pressure gauge on the right...

This is a TEST tank... which i think i'll make later on into a quarentine tank when i get the 29 gal, setup.


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## redfishsc (Aug 29, 2010)

Naekuh said:


> Red 3W LED's x 4 in serial wireup. 660nm range.
> 
> I was thinking it would give me a lot more red hue, but the 10W x 3 over powers it to almost nothing..



If those are the common red chinese imports you can get on Ebay, their output is considerably lower than a Cree, by nearly half. Of course they are also a lot cheaper lol.

I own both--- I have some from Satistronics but they are basically the same thing you get everywhere else. I also have red Cree XPE. 

Here is the result of driving each at 700mA and tested by a radiometer. Notice the Cree peaks out at nearly double the intensity. 












The red Cree's are quite crazy. I have 8 of them that were given to me by a friend that I'm going to make into a night vision fishing light for our canoe. Red won't draw buts (supposedly) and doesn't mess up your eye's focus as much, so should work great.


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## jor8888 (May 31, 2011)

I use 2 of these with my T5 they add extra 80% brightness for 5w power and my T5 uses 26W. http://www.amazon.com/Brightest-LED...AIIE/ref=sr_1_1?ie=UTF8&qid=1319684385&sr=8-1


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## Naekuh (Oct 19, 2011)

redfishsc said:


> If those are the common red chinese imports you can get on Ebay,


yeah i was wondering about that..

also, they weren't that cheap compared to the regular red because it specifically said 660nm. 

im assuming there the same guys as the OSRAM ones here:
http://www.rapidled.com/servlet/the-172/Osram-660nm-3W-Red/Detail

so did i get con'd? 

Red in general means 660nm? or is there specific 660nm leds? :bounce:

This is where i the newbie learns his mistakes...


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## HolyAngel (Oct 18, 2010)

where'd you get the cool white 10w's? i can only find warm whites :/


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## Naekuh (Oct 19, 2011)

HolyAngel said:


> where'd you get the cool white 10w's? i can only find warm whites :/


E-Bay >.< 

get the circle ones also...
did more research, and the squares are 160 degree's
The circles are 140 degree's. 

Also closer inspection shows the circle has the array's tighter packed, hence i think you can get better light control with the circle ones vs the squares.
20W LED's range is 15-17V, which might be too dim on a 12V setting.. so i wouldnt go with 20W, also the heat from a 10W is no joke.. 20W i dont even want to calculate that. 

The squares tho makes nice pendants from what im seeing.


But in search type high power 10W LED cool white.


Also 4 x 3W will give more light at less heat from what im seeing also, another + on the 3W, however the 10W is a lot easier to wireup and replace if it should ever burn out. And cost no more then 5-6 dollars shipped. 
But have a NASTY 2 week shipping time if your USA. 

No serial or solder required for the 10W's if your going to use a PC PSU class. (12V range).

i got 10 x 10W circles coming in... my brother after following this thread is sold on LED's.. lol.. 
So i'll probably make him a LED hood with 2 x 10W for his 10Gal, and 5 x 10W + 4 x 3W red's for his 75 gal


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## evilc66 (Feb 28, 2008)

Naekuh said:


> yeah i was wondering about that..
> 
> also, they weren't that cheap compared to the regular red because it specifically said 660nm.
> 
> ...


"Red" as a color ranges from about 615-700nm. The closer you are to 615nm, the more orangey the color looks. The closer you get to 700nm (beyond that is near infrared), the deeper the red. 660nm reds are considered "deep red", and aren't all that common when compared to 620-630nm reds. There are some companies that do 680nm reds. Edison calls theirs "hyper red".


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## redfishsc (Aug 29, 2010)

Evilc66 is right about the red spectrum. 


The 660's are basically thought to be more photosythetically active, and they probably are if the graphs of chlorophyll I've seen are correct. 

However plants are quite adaptable and I'm convinced that it really won't make a hill of beans difference between the 630nm and the 660nm, if the two LEDs being compared (rhetorically speaking) are of the same basic light output (PAR)


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## doonie (Oct 27, 2011)

First thing you need to do is get some defectors and lens. I have a 30w 6500k single led on my 10g and with out a lens all it did was light up the room, after the lens the light reached deeper and brighter, and my light is 8 inches from the water. I also added 4 3w blue leds for a better cooler. I run the 30w off it's own driver and the 3w's and heat sink fan off a computer power supply. All 5 leds are mounted on a single Pentium 3 long heat sink with a single fan, I also used arctic silver heat sink compound(important). It runs about 105-110 degree's steady for 8 hours. The other question is why is every one wiring in series , if one led blows so will the rest , a computer power supply could run up to like 30 plus 3w leds , or 90x1w and still be safe, most have a steady 3.3v rail. and can be found for next to nothing.


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## evilc66 (Feb 28, 2008)

The reason we run in series is that it's safer. Sure, it creates a few more headaches when it comes to tracking down the faulty LED, but it's better than the alternative.

When run in parallel, you divide the current from the current source (I'm strictly talking about using constant current drivers here, not constant voltage PC power supplies or similar). When one LED, or string of LEDs goes out, then problems arise. If we are talking about LEDs in parallel with no more than one LED in each string, then if one LED goes out, the current is divided among the rest. Not so bad if you have a lot of LEDs in series, as the increase in current is minimal at each LED. 

If you only have two or three LEDs in parallel, the effect is obviously much greater. If you have a 2100mA driver, and three LEDs in parallel (that are designed to have no greater than 700mA driven through it, like most Chinese LEDs), each LED would see 700mA. Kill one LED, and the remaining two now see 1050mA each, which will put a lot of stress on the remaining LEDs. You also have an issue in this senario with differences in forward voltage. Because the driver is trying to put out a fixed current at a certain voltage, the differences in forward voltage on each LED can change the amount of current each LED takes out of the total available current (i.e. not everything is divided perfectly equaly), and can alter the brightness of each LED.

When you start running multiple LEDs in series in parallel strings, you get all the issues above, with a few more. The problems come from losing an LED in one string. If the LED fails open, it takes the entire string out, and acts like the issue mentioned above. If the LED fails closed (a short), the rest of the string is still lit, but is now being driven harder than it should due to the new change in forward voltage. The increase in forward voltage now increases the current. Remember, small increases in voltage lead to large increases in current, and heat.

There are a few tricks that can improve the reliablility of parallel arrays, but as a general rule, I tend to avoid them. For two parallel strings, current mirrors can work, but don't save against all failure modes (works with open failures, but not closed failures). They don't work well beyond two parallel strings. Grid wiring, where every LED is basically connected to the other works when used with three strings or more. It tries to share the load of a failed LED across the entire array. It works to a degree, but the stress is still there, albeit spread out a lot more. It's also a wiring nightmare.


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## Naekuh (Oct 19, 2011)

evilc66 said:


> If you only have two or three LEDs in parallel, the effect is obviously much greater. If you have a 2100mA driver, and three LEDs in parallel (that are designed to have no greater than 700mA driven through it, like most Chinese LEDs), each LED would see 700mA. Kill one LED, and the remaining two now see 1050mA each, which will put a lot of stress on the remaining LEDs.


this is what i dont understand.. a lot of u guys have been saying this when this doesnt apply to dc circuits. Maybe one of u guys can tell me why im not understanding this... 

if u had 4 x 3V 700mA led's and you wired them up in serial, you would effecitively make the array a 12V 700mA array consisting of 4 led's. 

Should one die... if in serial, all of them would die because you would lose one of the polarity in voltages due to the broken array. 
Serial is going A -> B -> C -> D if one dies... they all go out like xmas lights. 

I also dont understand how something can draw more current and not voltage. 
So if u had 4 x 12V LED's in paralell and they each drew 1A, your psu needs to be able to handle 4A load. 
If 1 would die... the remaining 3 LED's would not get the offset of 1.3A, they would still draw 1A, and your PSU would downthrottle the load to 3A, and not 4A. 

i was looking at the specs on the cree;s and they go by current, later translated with voltage. 

The CREE LED's 
http://www.cree.com/products/pdf/XLampXP-G.pdf

Pg. 4 shows @ 3V these guys draw 350mA. 
As you increase voltage, the current draw increases... so im to believe as you increase voltage, the current will increase as well exponentially, and that is why im seeing all this heat being dump'd into the system.

Ideally i think, and please someone corrent me if im wrong, the Cree 3W LED's which can do almost 4V each, should be better paired with a meanwell 12V PSU with a variable pot that would allow it to go up to 14V. 

Then i believe u can get the full spec's on the cree' LED's or get a 10V meanwell, and run 3 in serial. <--- now i see why the 10V meanwells are so popular here....
@ almost 3.3V each collectivly a 9.9V array @ 10V, you could get 1A of current though the CREE LED's for the most optimal lighting intensity?

Once again.. someone please correct me if my physics is off..


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## redfishsc (Aug 29, 2010)

Naekuh said:


> this is what i dont understand.. a lot of u guys have been saying this when this doesnt apply to dc circuits. Maybe one of u guys can tell me why im not understanding this...
> 
> if u had 4 x 3V 700mA led's and you wired them up in serial, you would effecitively make the array a 12V 700mA array consisting of 4 led's.
> 
> ...


What Evilc66 is talking about is the fact that you're using a constant current driver which compensates for the load when you blow an LED (when the LED blows in a way that allows current to pass). That LED no longer works, but if the dead LED is allowing current flow, the others work just fine. 

I've had this happen before. 

Even if it blows "open circuit" and stops the current flow, the other LEDs stop working but they aren't damaged. You just need to replace the dud or jumper around it.





> I also dont understand how something can draw more current and not voltage.
> So if u had 4 x 12V LED's in paralell and they each drew 1A, your psu needs to be able to handle 4A load.
> If 1 would die... the remaining 3 LED's would not get the offset of 1.3A, they would still draw 1A, and your PSU would downthrottle the load to 3A, and not 4A.


You're designing this situation around a constant voltage power source, not a constant current power source. The problem here is that very very very few of us use constant-voltage power sources for LEDs and thus your illustration doesn't apply.


The constant current power source is simply just going to put out what it's rated for (or where the dimmer is set at). If it's a 4 amp CC power supply, you get 4 amps out of it regardless of how you wire your LEDs. The current that goes to the LEDs depends on if you use series or parallel strings, but the driver will always give you 4 amps.

If you have 4 parallel individual LEDs then you get 1 amp per string. If one blows, you absolutely DO get 1.33 amps per string, which may be too much for your LEDs. 

If you are driving XPG or XML, this wouldn't matter. They can handle the added load, but if you are driving chinese 3-watters then you will probably blow them all. 



> Pg. 4 shows @ 3V these guys draw 350mA.
> As you increase voltage, the current draw increases... so im to believe as you increase voltage, the current will increase as well exponentially, and that is why im seeing all this heat being dump'd into the system.



We don't fiddle with the voltage on a constant current LED driver. The driver does all the fiddlin' we need. As long as you know the voltage ranges (ie, the min/max number of your LEDs it will drive) the driver will automatically adjust it's voltage output to the sweet spot it needs to give the LEDs the necessary current (it's rated current output).



> Ideally i think, and please someone corrent me if im wrong, the Cree 3W LED's which can do almost 4V each, should be better paired with a meanwell 12V PSU with a variable pot that would allow it to go up to 14V.


Meanwell makes both CC and CV power supplies, be sure you aren't talking about a Meanwell CV power supply. 

You do NOT want to be setting up a high power LED array using a common potentiometer to adjust the circuit's voltage---- I think that's a bit too much for a standard ratshack potentiometer to handler. Absolutely don't do it on a constant current driver--- the driver will only compensate for the added load by increasing voltage, I believe. 





> Then i believe u can get the full spec's on the cree' LED's or get a 10V meanwell, and run 3 in serial. <--- now i see why the 10V meanwells are so popular here....


The most common Meanwell on here is actually a 48 volt CC driver, the ELN-60-48, and I own 4 of them myself (in addition to buckpucks and a pile of DX chinese drivers). 

I have never seen a Meanwell 10v driver. Unless you are confusing the 10v rating for the 0-10v dimming circuit. A Meanwell uses a 10v reference voltage as a dimmer switch, but that 10v (and the associated power supply giving the Meanwell this 10v) has nothing whatsoever with the power driving the LEDs, other than controlling the dimmer. The power driving the actual constant-current driver is 120VAC wall power.


The 10v dimmer circuit doesn't equate into the LED array whatsoever. 


And for those reading, you DO NOT need to worry about getting a solid 9-10v input. You can literally use a cell phone charger (5-6v). All you need to do is to pop the Meanwell's top cover off, find the SRV2 screw, hook up your multimeter to test the current going through the LED array, and tweak that SRV2 screw up until you reach your desired max current (usually around 700-1000mA). 

I've done this on 6 different Meanwells now (two of my own, 4 of a buddy) and it works great. That's why they put that SRV2 in there.


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## evilc66 (Feb 28, 2008)

Red covered most of the issues pretty well. I want to throw in some additional information though.



Naekuh said:


> this is what i dont understand.. a lot of u guys have been saying this when this doesnt apply to dc circuits. Maybe one of u guys can tell me why im not understanding this...


Careful. You didn't read the fine print in what I wrote. And yes, it does apply to DC circuitry. Just not all DC circuits.



> if u had 4 x 3V 700mA led's and you wired them up in serial, you would effecitively make the array a 12V 700mA array consisting of 4 led's.
> 
> Should one die... if in serial, all of them would die because you would lose one of the polarity in voltages due to the broken array.
> Serial is going A -> B -> C -> D if one dies... they all go out like xmas lights.


That's only true if the LED fails open. LEDs have two failure modes though; open and closed. Each one will give a different result. If the LED fails closed, the entire string stays lit, with the exception of the one that failed.



> I also dont understand how something can draw more current and not voltage.
> So if u had 4 x 12V LED's in paralell and they each drew 1A, your psu needs to be able to handle 4A load.
> If 1 would die... the remaining 3 LED's would not get the offset of 1.3A, they would still draw 1A, and your PSU would downthrottle the load to 3A, and not 4A.


Again, you are not reading what I wrote correctly, and are taking things out of context.

In a constant current setup, which I outlined in my last post, the driver is always pumping out the same current, regardless of if you have one or 10 LEDs hooked up. The current always divides equally between parallel strings on a constant current setup.

In a constant voltage setup, which you are refering to, the current draw from the power supply will only be what is required by the LEDs connected. What you have to pay attention to with this kind of setup is making sure that the total forward voltage of a series string, and the output voltage from the power supply are within each other. Effectively, you are dividing the voltage among the LEDs, where as with a constant current setup, you are dividing the current between the LEDs.



> i was looking at the specs on the cree;s and they go by current, later translated with voltage.
> 
> The CREE LED's
> http://www.cree.com/products/pdf/XLampXP-G.pdf


Cree isn't showing you how to drive the LED by voltage with the voltage curves shown in the datasheet. It just shows you the expected *average* voltage based on a certain current.



> Pg. 4 shows @ 3V these guys draw 350mA.
> As you increase voltage, the current draw increases... so im to believe as you increase voltage, the current will increase as well exponentially, and that is why im seeing all this heat being dump'd into the system.


Correct. This is one reason that LEDs really should be current driven. Small changes in voltage can make huge changes in current.



> Ideally i think, and please someone corrent me if im wrong, the Cree 3W LED's which can do almost 4V each, should be better paired with a meanwell 12V PSU with a variable pot that would allow it to go up to 14V.


No. That voltage is an average based on data that Cree has on their production parameters. It does not guarantee that at a certain voltage, the LED will produce X amount of light, or draw Y current. Now, when driven at a certain current, you pretty much know what your light output is going to be, even though the forward voltage of each LED may be different by a bit.



> Then i believe u can get the full spec's on the cree' LED's or get a 10V meanwell, and run 3 in serial. <--- now i see why the 10V meanwells are so popular here....
> @ almost 3.3V each collectivly a 9.9V array @ 10V, you could get 1A of current though the CREE LED's for the most optimal lighting intensity?
> 
> Once again.. someone please correct me if my physics is off..


If you are looking for optimal light output (i.e. even intensity across the entire array), then you should be current driving the LEDs. It will give you the most consistancy and reliability. If LEDs were intended to be voltage driven, constant current LED drivers wouldn't exist. Seeing as they do, they may be there for a reason 

Think about this for a second. Take three LEDs from different manufacturers (fictional in this case). Each LED is rated to produce the same light output at the same current. Each LED though has a different forward voltage. If you were to build an array for each LED type, and used a constant voltage setup, you would have to adjust the voltage for each array to get the desired results.

With the same arrays, and a constant current setup, all you would need to do is pick a driver that has the desired current output, and enough voltage to cover the highest forward voltage LED array. Simple. No adjustment, and consistant results across each array.

This may sound far fetched, but it's happening right before us. Each generation of LED is dropping the forward voltage lower and lower. Chinese LEDs are typically 37.v-4.0v at 700mA. XR-Es are about 3.5v at 700mA. XP-Gs are 3.2v at 700mA. XM-Ls are about 2.9v at 700mA. Why go to the trouble of fiddling, adjusting, and correcting a constant voltage setup, when you can just specify the current and be done with it?


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## Naekuh (Oct 19, 2011)

wow thanks red and evil... yeah u nailed basically everything i was confused about.

and this rheobus is raited for 1.62A per channel which i think is enough for a led.

and yeah im playing with constant voltage, and not constant current.. i guess thats why i was getting really confused.


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## redfishsc (Aug 29, 2010)

Naekuh said:


> wow thanks red and evil... yeah u nailed basically everything i was confused about.



The reality is, you're basically just dealing with EvilC66..... there is very little about LEDs that I know, that he didn't teach me.


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## Hoppy (Dec 24, 2005)

One more thing, which probably doesn't cause any problems, but theoretically could: If you put two strings of 12 LEDs in parallel, it would be a coincidence if the total of the forward voltages were the same for each string. Now, when a constant current driver powers that pair of parallel strings of 12 LEDs, it will adjust its voltage so that the current is what the driver is set for, say 700 mAmps. But, suppose the voltage that is required for one of the two strings is 12 x 3.5 volts, or 42 volts, and that required for the other string is 12 x 3.4 volts (it could happen in theory) or 40.8 volts. The driver must supply a voltage so that the total current is 700 mAmps, but that could be 100 mAmps through one string and 600 mAmps through the other string. You would have one very dim string and one very bright string. I haven't seen anything like that happen, so that should show that all LEDs in one batch or bin tend to have almost the same forward voltage vs current. I just keep wondering about this.

Now, I'm wondering if you could put a low resistance pot in series with say the warm white LEDs, which are in parallel with the cool white LEDs, and control the color mix that way?


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## DarkCobra (Jun 22, 2004)

Hoppy said:


> I haven't seen anything like that happen, so that should show that all LEDs in one batch or bin tend to have almost the same forward voltage vs current. I just keep wondering about this.


In theory, the forward voltage (Vf) of each LED is an equal random distribution around what's listed in the datasheet. So the more you have in series, the more these random variations average out. Of course if there's poor quality control, or you're just unlucky, the differences may be additive.

But even then, the eye is not good at detecting these mismatches due to its logarithmic response, which falls off in accuracy rapidly as things get brighter. And LEDs are certainly bright! If you really want to know what's going on, check the actual current on each string.

Cheap mass produced LED products often rely on the average Vf per string being the same, then use cheap LEDs which almost guarantee it's not. For these, the differences are sometimes large enough to be seen by the naked eye. And the same products usually attempt to run all the LEDs at full rated power (or sometimes beyond!) on top of that, which due to the Vf mismatches, cause even more stress and premature failure.

Even single LEDs with multiple dies, and several internal series strings, can suffer from this. Consider this questionable Topbright 100W from Hong Kong, run at a very dim 10ma:










You can tell it's arranged internally as 10x vertical strings of 10x 1W LED dies. Four dies have unusual Vf, and you can see the effect on their string.

If you visit the website this image comes from, you'll also see a picture at 100ma, and the poster says all dies are equally bright at that power. _They are not_. Although an camera sensor has linear response, it must post-process that to a logarithmic response just like the human eye, otherwise photos would look very strange indeed. That's why a camera needs an _internal_ brightness resolution of at least 4,096 levels to produce an accurate image with only 256 levels; else there will be gaps, and some output levels will never exist, due to the lossy linear-to-log translation. But I seriously digress. 

Suffice it to say that because the 100ma photo is brighter (despite taking it through welding goggles and much shorter exposure), the logarithmic response hides brightness variations. And unlike the poster, I can still clearly see three of the four bad dies. If run at 100W, I wouldn't expect this LED to last anywhere near it's claimed lifetime for that power level due to these mismatches.

But for a DIY light, where LEDs are typically being run well below full power and with generous heatsinking, Vf mismatches aren't much of an issue. You have plenty of leeway.

Hope that satisfies your wondering. I may have geeked out a bit. :hihi:



Hoppy said:


> Now, I'm wondering if you could put a low resistance pot in series with say the warm white LEDs, which are in parallel with the cool white LEDs, and control the color mix that way?


You could. It would be wise to insure that if one LED fails open, thus disabling that series string, the other string can take the full current by itself for long enough for you to fix the problem. Also check that you don't exceed the maximum power dissipation for the pot. Some are quite low.


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## Naekuh (Oct 19, 2011)

DarkCobra said:


> Suffice it to say that because the 100ma photo is brighter (despite taking it through welding goggles and much shorter exposure), the logarithmic response hides brightness variations. And unlike the poster, I can still clearly see three of the four bad dies. If run at 100W, I wouldn't expect this LED to last anywhere near it's claimed lifetime for that power level due to these mismatches..


wow thanks for your input. 

and yes i noticed these mismatches also, also i noticed that its a prelude to the led starting to die. 

Ive ordered a lot more to play with because i actually killed one on purpose running it off a sink for giggles sake to see how long it would take to kill a 10W led.

you guys want to know? 5 seconds...

At the 5th second the led is well into the dangerous heat point and litterally starts to smoke. 

Afterwards u see the solder inside the led array litterally melt, and only 3 of the 9 arrays light up now. 

Also i dont expect these LED's to last very long at 12V. (which is why i got another 20 arriving to play with. :biggrin

Multimeter says they pull well into 900mA at 12V putting them well over the specs of the running parameters of 1x9 1W LED arrays.


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## doonie (Oct 27, 2011)

So which would be brighter a led on constant voltage or constant current ? Or would they be the same ? My understanding is current is draw , some thing can only draw so much power= amps , amps also change with voltage. a dc motor will pull x amount of amps at x amount of volts . Wouldn't an led be the same? If you are limiting the current aren't you limiting the voltage? 

I don't completely understand this that's way I'm asking. I also still don't understand the benefit of running constant current in series over constant voltage in parallel.


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## DarkCobra (Jun 22, 2004)

doonie said:


> So which would be brighter a led on constant voltage or constant current ? Or would they be the same ? My understanding is current is draw , some thing can only draw so much power= amps , amps also change with voltage. a dc motor will pull x amount of amps at x amount of volts . Wouldn't an led be the same? If you are limiting the current aren't you limiting the voltage?
> 
> I don't completely understand this that's way I'm asking. I also still don't understand the benefit of running constant current in series over constant voltage in parallel.


LEDs pass no current until you reach their forward voltage (Vf), which is often 3.2V or so, but may vary according to type or even between individual LEDs of the same type.

Once you reach Vf, they start to conduct, and the current flow rises _rapidly_ with relatively small further increases in voltage; just a few tenths of a volt until you reach max rated current.

You can achieve the same LED brightness with either constant current or voltage, since they are after all related. But the devil is in the details when it comes to making a reliable LED system. And if it's a big expensive one, you want it to be _very_ reliable.

Suppose you have a LED, driven by constant voltage, on a heatsink with a fan. It operates fine day after day, until the fan fails. The LED gets hotter. Heat causes the Vf to drop, resulting in more current flow, which causes the Vf to drop, and so on until the LED may finally burn up. This is called thermal runaway.

With a constant current driver, if the fan fails, the LED will still get hotter and the Vf will drop, but the driver will allow no additional current to flow. No thermal runaway, and the LED has a better chance of surviving until the fan is fixed.

For a series string of LEDs, if one fails prematurely, you want the others to survive.

If one fails open, it results in no current flow. No difference whether you're using constant voltage or current, the entire string shuts down; and no damage is done.

But if one fails closed (as a short-circuit), or if there is a short-circuit in your wiring, there is a difference. With a constant voltage driver, current will increase through the remaining LEDs which may by itself, or in combination with thermal runaway, cause damage. With a constant current driver, no damage is done at all; the remaining LEDs continue operating the same as before.

Different scenarios apply to LEDs in parallel, and it gets really tricky if you use serial and parallel combined. Neither a single constant current or voltage driver will gracefully handle all the myriad failure and mismatch possibilities; though a constant voltage driver actually works somewhat better in this case.

I won't go into full details on that, because the _best_ way to go about it is to put as many LEDs on a series string as possible, with a constant current driver. And if you exceed the maximum number of LEDs the driver will handle, then start a new series string with another driver.


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## Naekuh (Oct 19, 2011)

DarkCobra said:


> Suppose you have a LED, driven by constant voltage, on a heatsink with a fan. It operates fine day after day, until the fan fails. The LED gets hotter. Heat causes the Vf to drop, resulting in more current flow, which causes the Vf to drop, and so on until the LED may finally burn up. This is called thermal runaway.
> 
> With a constant current driver, if the fan fails, the LED will still get hotter and the Vf will drop, but the driver will allow no additional current to flow. No thermal runaway, and the LED has a better chance of surviving until the fan is fixed.
> 
> ...


Yes thermal runaway... ive been playing with this...

cv and cc.. im slowing learning this. 

CC is required for dimmers also from what i was seeing... dimming via voltage i hear can damage the led however ive been undervolting one of the original squares i got since day 3, with no ill effects.

I got the circle 10W i'll post pictures soon. 


Also cobra from what im seeing the 10W, it wouldnt matter if u went on CC or CV.

if your sink isnt good, and your fan dies, the 10W beam can get hot enough to melt acrylic on the underside. 

Fan failure is a big no no.... but lucky for me i have monitors which squeel when a temp gets X C on the diode. 


Also, im more comfortable with CV then CC. Only because ive been playing with CV to a point where i can build my own stuff with a multi meter. 

CC, is a new concept to me.. and i feel i would mess more stuff up on CC because i would need to bench my work desk and start over with new gear on CC.

Updates:
So i got my 20 x 10W Circles..

You can see the arrays packed tighter then squares:









The heat sink for the base is also thicker..









My array is setup like this 3 x 10W and 4 x 3W reds..









Sits on top of the tank like this:









Well i have a problem now...









^ that picture should tell you enough... lol... i think i need to inject more CO2, and clean the canister.
Also i think im going to be spending some time with my syringe and h2o2 this weekend.

Sad thing is during these led tests, i can not reduce my photoperiod.. othrewise i will invalidate my stress tests on these led's.
so im lost... should i just remove the rock? the algae seems to be mostly centered on that rock... or should i leave it be?

Will it go away with more co2 injection?


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## doonie (Oct 27, 2011)

thank you DARKCOBRA ,

one more question , is there any difference in the Chinese drivers and say a Meanwell or is it just a difference in build quality?


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## Naekuh (Oct 19, 2011)

doonie said:


> thank you DARKCOBRA ,
> 
> one more question , is there any difference in the Chinese drivers and say a Meanwell or is it just a difference in build quality?


I live by meanwells... if you honestly ask me. But the meanwells i use is CV. 

i have a 320-12 220-24 and a 600-12.

But i live by them because i needed a high power psu for my TEC's. 

Meanwell's have quality... i'll give you that... and any of the ones i listed are overkill for a LED array, unless ur going MASSIVE.


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## doonie (Oct 27, 2011)

Naekuh get some lens and defectors for your leds, you will think you added twice the leds. It makes that big of a difference.


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## Naekuh (Oct 19, 2011)

doonie said:


> Naekuh get some lens and defectors for your leds, you will think you added twice the leds. It makes that big of a difference.


LOL i think you missed the point in that i have too much light now.. and too long of a photo period.

:bounce:

Can't you see the green cotton candy? :icon_mrgr


its so bright inside, my fish are scared to go out in the center... :\

Oh well, plants > fish right?


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## doonie (Oct 27, 2011)

With lens and defectors you can raise it up over the tank , my 30w is 8 inch's from my water level and the light goes into the tank.


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## Naekuh (Oct 19, 2011)

doonie said:


> With lens and defectors you can raise it up over the tank , my 30w is 8 inch's from my water level and the light goes into the tank.


lol true.. but with a lense i think i would get a stronger light focus.. 

meh.... these lights config is no good if its going to spawn green cotton candy. :\

i see my HC's growing tho... they even took root in substrate thats not on the rock.... probably because theres root tabs inside the eco complete...
But that lava rock is getting out of hand... i blame petco... but its the only place where i could find HC.


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## redfishsc (Aug 29, 2010)

Regarding the photo below, that thicker base plate on the round LED is not necessarily a better quality. 

If you have a good heatsink you are mounting the LED to, and good thermal compound/epoxy, you are actually better off with a thinner baseplate.The thicker baseplate retards the heat transfer from the LED chip to the main heatsink. 


Now, that being said, it's not really a big deal. Flashlight modders will often take a belt sander and grind the baseplate down to 1mm thick, but that's because they are overdriving them frequently and they need some serious thermal transfer. You won't need to mod this one.


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## doonie (Oct 27, 2011)

you need to add more ferts and more co2 , that should fix the problem or make it worse. that just what I have heard lol I seem to be growing some algae also but this tank just finished cycling so we will see what happens.


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## Naekuh (Oct 19, 2011)

doonie said:


> you need to add more ferts and more co2 , that should fix the problem or make it worse. that just what I have heard lol I seem to be growing some algae also but this tank just finished cycling so we will see what happens.


lololololol.....

yeah been adding more co2... my drop checker said i was near the darker green, so im gonna pump co2 til it gets near lighter green. 



But i think the red's are what giving me my algae bloom.
Thinking if i need to remove them..

Also i read more red light makes plant grow taller, while bluish light makes them grow shorter.



redfishsc said:


> Regarding the photo below, that thicker base plate on the round LED is not necessarily a better quality.


actually it uses more materials.. and the bigger base allows the led to last a couple more seconds longer without a sink then the first one.

Does a couple more seconds matter? not really..  

The light wise, the circle is a bit more focused vs the square.

And i was thinking of drilling my heat sink on round 3.... however... my M3 tap, is still too big for my LED holes. :\




Another note.. i threw in 3 ghost shrimps to see if they could take care of the algae problem i have.
Well they arent... they like to eat the food i feed the fish.
But whats funny is they get tangled in the hair algae and pull it off my plants, and then they chill in some location getting the algae off themselves.
So they are doing half the job.. lol...


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## Naekuh (Oct 19, 2011)

Updates!

Got some 3W - Chinese Cree's  
This is the LED's being run at 9V controlled via rheobus. 








*
The specs for them is ALL OVER THE PLACE... *
I should of expected this... these look lower grade then the 10W. 

@ 3V, the intensity was very poor. At first i thought i got bad LED's til i started testing them with a 4V battery. (I dont recommend this, i was prepared to lose the LED, but i wanted to see if that was it on luminosity.)









Well my gamble was good, these LED's need to be run at 4V to get anywhere close to decent luminosity. It will probably eat its life tho, but these were around 1.25 each with shipping. 

You guys probably want to see how they compare against a 10W.
This is both 10W and 3 x 3W:









This is 10W Solo:









This is 3x3W Solo:









This is 10W x 3 + 3W 660n x 4 + 3W x 3 = 51W of LEDs! 









^ and that is my dying tank from all the testing im doing.. :help:
Well its recovering.. after an ich attack + algae attack... the ich is almost gone... algae is almost dead... fish are FINALLY happy.

Well at least the fish are happy... :hihi:

Also i had to upgrade the PSU, im using a full blown PC power supply now, as i think i have potentially neared the 5Amp max the original one i was using... :icon_twis

I think the 3x3W has the potential to be better then a 10W if i use lenses on them... 
I guess im gonna now go shop for lenses.


EDIT:
i think i figured out my final array...









^ overkill?  

12 x 3W 5000-8000k
4 x 3W 660nm range
2 x 10W 5000-7000k

red or evil, can u guys tell me if im gonna have a problem with this much light in the future?

I think its too much after evaluation... i may go this route...









i removed half of the 3W whites.


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## redfishsc (Aug 29, 2010)

I did comment on your PM but I'll answer it here since I now remember you're doing this over a 10g tank, but yes that is overkill unless you use a dimmable driver. I imagine you would struggle to keep algae at bay if you ran them any higher than 300mA.


I ran a planted tank on a SINGLE 10-watter, identical to yours--- grew sword plants, crypts, dwarf saggitaria. Slowly--- it was "low-med" light. 

I then upgraded the tank to 4 Cree XML at 1,000mA (around 12-14 watts) and the light increase was easily double (they are just way more efficient) and started getting algae hell. 


What you have is probably sufficient for a 40g tank at "med" light.


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## Naekuh (Oct 19, 2011)

ahahaha... yeah i am struggling with algae... But its my first time with plants and CO2, and im having a blast. 

The middle row is the red's, while the top and bottom are the white's. The big ones are the 10W. 

I used to be a Reef person, so for me, it was all about bright and blue, but not too bright or you bleach... 

With plants its not like that... and keeping up with CO2 injections with Light.

Im learning so much new info about this side of the hobby that its fun.


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## WingoAgency (Jan 10, 2006)

Naekuh said:


> Also i dont expect these LED's to last very long at 12V. (which is why i got another 20 arriving to play with. :biggrin
> 
> Multimeter says they pull well into 900mA at 12V putting them well over the specs of the running parameters of 1x9 1W LED arrays.


I don't quite follow some of what you say.

Why are you saying "(the 10W will not) last very long at 12V"? Are using a voltage driver instead of a current driver? For power LEDs, and even higher power LEDs, you should use constant current driver. Voltage drivers have many disadvantages whenever it's paired with power LEDs due the thermal runaway characteristic, variable resistance due to environments, high heat generations....


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## Naekuh (Oct 19, 2011)

WingoAgency said:


> I don't quite follow some of what you say.
> 
> Why are you saying "(the 10W will not) last very long at 12V"? Are using a voltage driver instead of a current driver? For power LEDs, and even higher power LEDs, you should use constant current driver. Voltage drivers have many disadvantages whenever it's paired with power LEDs due the thermal runaway characteristic, variable resistance due to environments, high heat generations....


no i am using a constant voltage psu. 
The ones meant for pc's. 

If i was using a constant current driver, yes i think i would be able to extend the life of these guys.

The constant current driver is 12V, and goes up to 900mA. 
My multimeter is reading these guys at 12V, pulling near 1amp. 

Im starting to see why u guys go constant current, but all my gear is shifted to constant voltage from my other hobby. 

I have the spare parts, i might as well play with it. Also it would be very expensive for me to use constant current drivers at different amperage for 68W of total led lights as a test. :\ 
4 led's are 3V at 700mA. 6 are 4V at almost 1Amp, 2 are 12V at 900mA. 


But these led's are surprising me for sure.
They are lasting quite a while under the abuse ive been putting them though.


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## ugn (Mar 26, 2012)

Old thread, but how this testing go? 
What did you end up with, in this tank and the other 29g you where talking about.


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## Naekuh (Oct 19, 2011)

the 10W's won my test.

And i use the 10W's... 

I have a 40B now, which uses 6 of them on 2 x meanwell ELN 60-48P dimable drivers powering 3 each.


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