Ultimate LED guide

[evilc66]

So I've read this whole thread plus various other LED threads. I'm thinking about replacing the 150w MH in my JBJ 28 HWI with a LED setup. Obviously I don't want to just replace the MH...I gotta upgrade to something equivalent to 200-250w of MH light.

 

If 24 LEDs would produce ~150w of output, then I'd need ~40 LEDs for ~250w. Does that sounds right? And I'd need 40 degree lenses for each. And if I'm doing 20 white LEDs and 20 RBs, then I'd need 4 MeanWell drivers. 4 drivers is kind of expensive. Can you suggest a better setup for driving these 40 LEDs and controlling the RB LEDs separately?

 

For what it's worth, the JBJ is 18" x 22" x 22". I believe the canopy is 18" x 19" but that's just a guess since I'm at work and the tank is at home.

 

Does this plan sound reasonable? Got any suggestions? Thanks much!

 

Any real reason you want to go all the way to 250W levels? Thats a lot of light in a little area. Your biggest limitation is the area that you can fit a heatsink, and mount LEDs. Once you step to 40 degree lenses, it really reduces the area that is covered, and would normally need a larger area covered by LEDs. You don't have that larger area. 24 LEDs with 60 degree LEDs will be able to keep damn near anything you would like.

 

 

How much PAR do the Royal Blues alone have?

 

Keith

 

Quite a lot. From the tests I have done, royals produce just about as much PAR per watt as a cool white. It's difficult to say exactly how close they are, as most PAR meters are less sensitive in the blue range, and the results are reported low.

[sammy113]

Hey Evil, I bough a 24V 5A power supply for my 12 LEDS and a 24.5V fan for the heatsink just in case I can do something with it. Is there a way that I can plug it to the power supply also so when the lights go on the fan also? BTW when you have a break, take a look at my tank build, there are some pics of the LED lamp design and I would like your feedback I'm crazy to start the lamp build!

[evilc66]

Just hook the fan to the power supply. Fan comes on when the LEDs come on.

[Soneca-II]

:-)

 

starting to fell bad about always being requesting help :S

 

 

I'm not much on electronics, and the few university classes about the subject that i had already have several years ( need to find the books to read again... should had paid more attention :S )...

 

But, i was searching and found this driver , don't think its too expensive, but please give your oppinion. For what i had read i can place 16 1 Watt CREE XR-E or LUMIX K2 Also i believe i could manage do dimm the leds using this controller with the PWM using an arduino right?

 

 

Thanks again for you pacience

 

Rui

[evilc66]

Not a bad little device. Little pricey though. You will be able to drive a max of 10 white or blue LEDs, not 16. It's an issue of the forward voltage, not the wattage. This can easily be dimmed by an Arduino or similar controller.

[Soneca-II]

Humm, just 10 leds per devide.... That would be costy...

 

Do you know some other driver that would be cheaper?

 

I was looking at the www.national.com site, but i believe i don't have knowledge to mount one driver myself :/. At least in the near future it's not an option.

 

Can you please advise on a cheaper driver ( dimmable or not).

 

Best Regards,

Rui

[evilc66]

Well, it's better than 6 on a Buckpuck.

 

There aren't many choices currently available for high LED count dimmable drivers. One that we are starting to use is the Meanwell ELN series. They are line voltage (AC) with a dimming option, and a lot of power for large arrays. They are certainly not as cheap as the driver you showed.

[ChouDawg]

How many watts are Cree Royal Blues? I know BuckPucks can run 18@1w and 6@3w. I'm guessing they are 3w. I plan to do a custom probably 6-Royal Blue Cree LED supplement on my Sunpod. So one buckpuck should be fine? What mA output would be best?

[chazde3]

You can run the rbs at either 750ma or 1000ma.

[ChouDawg]

Any pros/cons on running them at lower/higher

 

Pros: More light

Cons: More heat, change in color?

[chazde3]

Any pros/cons on running them at lower/higher

 

Pros: More light

Cons: More heat, change in color?

If I remember right there isn't much of a noticable drop in par of the rbs at 750ma. I'm sure they will run a little cooler, doubt there will be much color change.

[ChouDawg]

Oh okay, in that case looks like 750mA it is, strictly actinic supplement so wont need potentiometer for dimming. Now to decide how to wire them (parallel/series), mounting, heatsink

[evilc66]

You always want to run strictly in series whenever possible. Running in parallel creates issues with voltage inequalities, and problems with failures. Also, you divide the current up between each parallel string, so you aren't getting 750mA to each LED anymore.

 

Careful with the statement of using 18 1W LEDs on a Buckpuck. This is understood as running 3 parallel strings of 6 LEDs. You are always limited to 6 LEDs in any series string. Like I said before, you always want to run stricktly in series whenever possible.

[ChouDawg]

Ah, okay thanks for clearing that up for me.

 

I'm taking Electricity & Magnetism Physics right now so I dont know too much about circuits.

 

Are LEDs considered resistors or capacitors? Or neither?

 

I remember for resistors in series: Voltage is constant, and in parallel: Current is constant, which sounds like it should apply to LEDs as well by your explanation.

 

Would 6 Cree in series be acceptable for one Buckpuck or would current drop substantially over the circuit?

[evilc66]

LEDs are diodes (Light Emitting Diode).

 

You have it backwards. All devices in a series circuit will have the same current. 1 LED or 6 LEDs in series will run at 1000mA if thats what the driver is set at. All devices in a series circuit will have a voltage drop across each device. That total voltage drop has to be equal to the source voltage (which is variable from the driver to match the changing voltage drops across the LEDs).

[Soneca-II]

Me again

 

still analysing the led DIY possibility and due to the startup price i was thinking in doing just half now for the first beguining of the aquarium ( build of the stand, aquarium, rock cycle and so on). Also would not invest the full value and first try with half.

 

 

I was looking in the led-tech and made this small list:

 

 

-> was checking the Luxeon. write ones for 10.000 Kalvin , blue one on 12000 kalvin using 500mA

LT-0955, Luxeon 1W Emitter , LT-0959, Luxeon 1W Emitter .

 

Should i go for the CREE ones for the bigger Lumen? and my question would be, aint the Kalvin enought? ( im confuse :S )

 

LT-1279, Power Supply for 6-10x 1W LEDs (230V). if i would stay with the Luxeon, this would be enought. But not for the Cree ones since it goes only to 750mA.

 

 

LT-1205, Heat Sink for 10mm PCBs (by the meter)

Was thinking in using a row like this, place underneat the stars. Is it a good idea?

 

 

Hope i'm not being too anoying :S

 

Regards,

Rui

[evilc66]

For a tank of your size, you need to run at a minimum of 750mA, no matter the LED. Ideally, you should be running Luxeon K2/Rebels, or Cree XR-E LEDs. Any of these LEDs can be run at this current. You may be looking at 1W LEDs to save some money, but you need the power to get a decent amount of light into the tank. There is no cheap way to do LEDs for a tank.

[M@rine_lover]

Hi evilc66,

 

Is it save or recommended to power up 2 string of 9 LEDs (parallel) from a constant current PS ? eg Meanwell ELN-60-27

 

or should I get ELN-60-48 to power 16 Leds?

 

Mind sharing what's the pro and con for both ?

 

Thanks.

Edited May 9, 2009 by M@rine_lover

[evilc66]

Well, to begin with, you can't do either of what you are asking. The ELN-60-27 can only do 7 LEDs in series (assuming a 3.7v forward voltage for white and blue LEDs), and the ELN-60-48 can only do 13. At that point, I don't think one additional LED is worth the effort of trying to safely run strings in parallel. Current mirrors, while simple and cheap, will be required at the end of each pair of parallel strings to prevent additional failure if one LED dies.

[STI470]

Is an 8.5" width heatsink too narrow for an 18" wide tank? The tank is 36 x 18 x 25 and per Evil's recommendation I will be using 90 LEDs with 40 degree optics. In planning my hood I started thinking that the 8.5" heatsink from heatsink USA will be too narrow and that 10.5" might be the minimum. If so, what width would be optimal?

[razornova]

Hi there. I've ordered 6 ssc royal blue leds that come premounted on a board. I have one of these lying around and was wondering if it could be use to run them.

http://www.internethobbies.com/lgbanthrotin.html

 

I am not adept in electronics but since the voltage can be varied does it mean I will be able to dim the leds with the throttle?

[STI470]

I don't know much about model trains but I would guess that the speed is controlled by varying the voltage. With LEDs, the intensity is controlled by varying the current. So I would say that you could not run LEDs off of it. You might be able to use it as an external dimmer control for a meanwell driver but it probably wouldn't be a good idea since the max voltage is 10 on these drivers.

[razornova]

Thanks for the reply. Guess I have to find something else.

[STI470]

Razor,

This is what I'll be using. Meanwell driver http://www.meanwell.com/search/ELN-60/ELN-60-spec.pdf

and this as a dimmer http://www.dimensionengineering.com/DE-SWADJ.htm

 

Since you are only using 6 LED you could always use a single adjustable buck puck and separate power supply.

There is a lot of good information on this website if you'll read through the threads. It takes awhile but can teach you everything you need to know to do it. I started out knowing nothing and have learned tons.

 

Here is a good thread on power supplies. http://www.nano-reef.com/forums/index.php?showtopic=183692

[Saiyan]

Hey Evil. I have a question.

 

I was only able to afford 2 drivers in the gb and 12 of each led.

 

What I would like to do is to make six 4 led lights (2&2)all powered off of the 2 drivers. Is this possible?

 

If it is possible would I then be able to add 2 pots to each unit and then make them dimmable on each channel as well?

 

Also how do you power fans?

 

Thanks