2x 50w multichip LED build critique

[Kairus]

I've seen a lot of good things about multichip LEDs, seems like good bang for your buck.

I'm planning on using two 20000k 50w chips. They're cheap Chinese ones, since I can't find any other ones that are reasonably priced. I think regardless I will have to dim them.

I plan on using Intel LGA775 OEM coolers, they're extremely cheap, less than $6 each and they should handle 50w easy (esp considering I'll dim them). The sandwich style will make it a lot easier to mount as well. This is what they look like

I'm not sure what driver I should go with, it needs to be dimmable, and I'd rather get one driver to handle both 50w LEDs so I don't have extra wires. I'd also rather go with a known brand like Meanwell, rather than those shady no name Chinese ones that claim they can power everything. So the LEDs have this information:

Forward Voltage (VF) : 32-34 Vdc
Forward Current (IF) : 1750 mA

I'm not the best when it comes to electricity, so if someone can point me in the direction of a dimmable driver that can handle two 50w LEDs, that'd be great. The only one I have found that can handle two of these LEDs would be this model, which isn't dimable. I need to be able to supply at least 3.5A correct? Could I get this driver and then add a dimmer in?

Can anyone point me in the direction of some decent optics? I hear 90 degrees is the typically the best to go with?

 

[Kairus]

Can't edit the main post, so I'll update it with what I've changed. I'm thinking about doing two 100w 460nm LEDs and two 50w cool white leds. Mostly for cosmetic reasons.

A Meanwell TEC-350-36. I should be able to run the 32-34vdc LEDs on this unit right?

What kind of dimmer can I get for a 36v driver?

 

[mcgyvr]

LED's require constant current NOT constant voltage power supplies..

For 50W I suggest 1 meanwell LPF-60D-36 for each LED
For 100W I suggest 1 meanwell LPF-90D-36 for each LED
and 100K potentiometers for dimming.

 

[Kairus]

LED's require constant current NOT constant voltage power supplies..

For 50W I suggest 1 meanwell LPF-60D-36 for each LED
For 100W I suggest 1 meanwell LPF-90D-36 for each LED
and 100K potentiometers for dimming.

I see. What about the NES-350-36? On the datasheet it says "built-in constant current limiting circuit". I'd still need a driver? I'm confused, since LEDs can't set power draw, they take whatever is given to them, how would I wire them up?

Honestly I'm thinking about cheaping out, buying four of these and using 30w LEDs. 120w should be fine for a 72? If I do SPS it'll only be in the upper region of the tank.

 

[mikmikjg]

Those are AC/DC constant current drivers. Make sure you match the current output of the driver with the IF of the LED chip you want to use. Also match the power rating and max output voltage of the driver to the chip, you can use a driver with a higher power rating and max voltage output than the LED to give the driver some headroom.

 

[mikmikjg]

I am currerntly planning out a similar project with only 1 50 watt multichip (full spectrum 5 channel). Maybe it will help you to read how I plan to lay it out:

48V 350Watt DC power supply (this is way overkill but it is cheap, I plan to run other lighting with it and or expand to 100 watt multichip)

This will feed 5 Meanwell LDDH on a 5up board with a current output to match the LEDs.

the meanwells are dimmable by 5v PWM so I will be using an analog to digital converter enabling me to independently dim 4 different color wavelengths using my Apex dimming outputs.

 

[perkint]

I see. What about the NES-350-36? On the datasheet it says "built-in constant current limiting circuit". I'd still need a driver? I'm confused, since LEDs can't set power draw, they take whatever is given to them, how would I wire them up?

Honestly I'm thinking about cheaping out, buying four of these and using 30w LEDs. 120w should be fine for a 72? If I do SPS it'll only be in the upper region of the tank.

If the supply is current limited, you may not need a driver. But is it PWM?

As for your cheap option - personally I would have a problem buying from someone who says "manual measurements so may be 1 or 2 cm out"!! Can't they use a tape measure?

How about ELN-60-48 supplies? I think they can take a PWM inout can't they? You'd need two tho...

Tim

 

[Kairus]

If the supply is current limited, you may not need a driver. But is it PWM?

As for your cheap option - personally I would have a problem buying from someone who says "manual measurements so may be 1 or 2 cm out"!! Can't they use a tape measure?

How about ELN-60-48 supplies? I think they can take a PWM inout can't they? You'd need two tho...

Tim

Yeah, that's somewhat sketchy, but it's just the seller writing that, they didn't produce the product. Then there's these. They sell a bunch of LED related stuff. 0.9A, so it would underdrive a 30w LED a little.

The ELN-60-48 seems like it would work, but I'd need 1 for each LED, cheapest I see them is $35, so $140 for power seems crazy. The only PWM dimmer I could find that works at that high of a voltage is a no brand Chinese one, and one for each driver would be another $45. There has to be a simpler way here. If companies can sell 120w LED units with one power supply I should be able to run 4x30w LEDs off one supply.

 

[Mike31154]

Although not recommended, using constant voltage supply is possible with some precautions. My DIY build uses 27 10 watt multichip LEDs on 3 rails of 9 emitters each. Two 12 VDC power supplies provide the juice with manual dimmers downstream to keep the voltage a couple of volts below the rated maximum forward voltage (Vf) of the LEDs I'm using. It's a parallel set up with all the emitters getting the same Vf from the dimmer that's feeding them. Been running for 2 years with no LED failure. Only hiccup is I cooked one of the dimmers a couple of weeks ago, but that's not because of poor dimmer quality, it's because I was running too many LEDs on that dimmer. I'll be fixing that forthwith. I should probably wire some fuses into the circuit as well!

Although the first photo below shows the voltage output from the dimmers at 5.0 & 4.9 Volts, I've actually been running at 8 to 8.5 volts for about a year. I recently installed a couple of larger power supplies to provide a bit more headroom in that department. It was a week or so after this, that the Royal Blue (RB) dimmer on the left failed. No surprise really since I had a total of 8 LEDs on that, so it's been running at near maximum 8 amp rating for a while. No idea why the 10K dimmer is unaffected, especially since it's running 10 LEDs.

Center rail has 4 6000K Whites & 5 Blues. Outer rails consist of 4 Royal Blue & 5 10000K White.

The roasted dimmer. 2nd dimmer at top of photo was a spare I patched in after removing the cooked one. MOSFET started overheating & smoking after only a minute, so that one's shot too. I have 5 new dimmers coming in the mail so I'll be able to split the load for the outer rails to keep dimmer current within the rating. Should have known better in the first place & not run them at the limit.

EDIT: I think if I were to start another build, I'd probably opt for fewer & larger emitters, 50 watt or so, with optics, mounted higher from the water surface. Less wiring.

 

[mikmikjg]

The ELN-60-48 seems like it would work, but I'd need 1 for each LED, cheapest I see them is $35, so $140 for power seems crazy. The only PWM dimmer I could find that works at that high of a voltage is a no brand Chinese one, and one for each driver would be another $45. There has to be a simpler way here. If companies can sell 120w LED units with one power supply I should be able to run 4x30w LEDs off one supply.

Just a suggestion:

1) Find a supplier for "30w led 45mil 20000k" on that same website you found the other chips that offers a chip with the following specifications:
30w led (30x1w)
Lens Color: Water Clear
Emitted Color : Pure White 6000~6500k / Warm White 3000~3500k / Cool White 10000-14000k / Cool White 16000-20000k
DC Forward Voltage (VF) : 30V~36V
DC Forward Current (IF) : 1000mA[/B]
View Angle: About 160 degree
Luminous Intensity: 2500~3000Lumen
Dimensions: L56mmxW52mmxH4mm

2) You can use a MeanWell LDDH 1000 to drive each chip (these are about 7.50 each, 38.50 total)
2.5) optional: get a coralux 5up board for 14.00 to mount the LDDH drivers or use the prewired LDDHW at no extra charge (I recommend the board if you plan to dim)
3) find one 48Volt power supply rated for at least 150 Watts (should be about 20 - 30 bucks)

You can run 5 x 30w leds (150 watts is the limit of the power supply), the power supply and driving circuitry will cost 70 to 90 bucks maybe. Each LED will be independently dimmable by a 5v PWM control source (which I would recommend doing since you do not really want to drive the power supply at its limit assuming that is 150 watts).

 

[zachts]

Although not recommended, using constant voltage supply is possible with some precautions. My DIY build uses 27 10 watt multichip LEDs on 3 rails of 9 emitters each. Two 12 VDC power supplies provide the juice with manual dimmers downstream to keep the voltage a couple of volts below the rated maximum forward voltage (Vf) of the LEDs I'm using. It's a parallel set up with all the emitters getting the same Vf from the dimmer that's feeding them. Been running for 2 years with no LED failure. Only hiccup is I cooked one of the dimmers a couple of weeks ago, but that's not because of poor dimmer quality, it's because I was running too many LEDs on that dimmer. I'll be fixing that forthwith. I should probably wire some fuses into the circuit as well!

Although the first photo below shows the voltage output from the dimmers at 5.0 & 4.9 Volts, I've actually been running at 8 to 8.5 volts for about a year. I recently installed a couple of larger power supplies to provide a bit more headroom in that department. It was a week or so after this, that the Royal Blue (RB) dimmer on the left failed. No surprise really since I had a total of 8 LEDs on that, so it's been running at near maximum 8 amp rating for a while. No idea why the 10K dimmer is unaffected, especially since it's running 10 LEDs.

Center rail has 4 6000K Whites & 5 Blues. Outer rails consist of 4 Royal Blue & 5 10000K White.

The roasted dimmer. 2nd dimmer at top of photo was a spare I patched in after removing the cooked one. MOSFET started overheating & smoking after only a minute, so that one's shot too. I have 5 new dimmers coming in the mail so I'll be able to split the load for the outer rails to keep dimmer current within the rating. Should have known better in the first place & not run them at the limit.

EDIT: I think if I were to start another build, I'd probably opt for fewer & larger emitters, 50 watt or so, with optics, mounted higher from the water surface. Less wiring.

What is doing the current limiting on you rig? if you are just using those PWM dimers and the LED directly wired in to the PSU it is a wonder you've not cooked the LEDs or started a house fire. That burned dimmer should be an indication something is wrong. You need resistors on the LEDs to run off a constant Voltage supply........

 

[mikmikjg]

The only PWM dimmer I could find that works at that high of a voltage is a no brand Chinese one, and one for each driver would be another $45.

Forgot to mention that if you use dimmable drivers like the MeanWell LDDH they are dimmable via a 5 Volt PWM signal, that is to say they are controller ready.

They would be plug and play with an inexpensive light controller like the Storm which has 6 output channels (5v PWM), sun up/down smooth ramping, lunar cycle, cloud pass simulation, and of course lightning and storm effects for whatever thats worth. I think it runs about 65 bucks

 

[perkint]

Agreed. Something like the LDDs and an arduino would be cheap, easy and work with any 38V power supply that can handle the wattage.

Or even head over to the DIY section and have a look at the boards O2surplus designed. 5 drivers on board, switchable current by jumper (various settings between 300mA and 1.4A), aduino and RTC on board. Cracking boards

Tim

 

[mikmikjg]

or even head over to the diy section and have a look at the boards o2surplus designed. 5 drivers on board, switchable current by jumper (various settings between 300ma and 1.4a), aduino and rtc on board. Cracking boards

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