LED EXPERTS - Help me match leds to drivers

BigJohnny · Nov 18, 2017

I am going to build a led supplement bar for my reef tank. I know that I want to use 50/50 450nm and 420nm leds. I found 6w Cree xp-g3 450nm and semiled hyperviolet 420-430nm leds on rapidled.com, but I have no idea how to determine what driver (or drivers since I think the cree are possibly double the wattage and a different type of led) to use. I would prefer to use the same type and wattage of leds, but I wasn't able to find equal 450nm and 420nm. Maybe there is a better website?

I will be using an aluminum heatsink from superbrightleds.com and was planning on just using the 80* optics from rapidled unless there are better options (they look pretty cheap).

Another thing I am unsure of is the # of leds to use and spacing. The bar will be 33" long.

Any advice would be greatly appreciated.

Thanks!

Mandelstam · Nov 18, 2017

Here's a good article on the subject that I found. https://www.ledsupply.com/blog/understanding-led-drivers/

Before you can choose the driver you need to know a few things, how many leds are you using, their voltage, how are you going to power them, do you want to control them with a micro controller, etc, etc.

Mandelstam · Nov 18, 2017

I would power them on two drivers so that I could control the two colors separately.

ReefEco · Nov 18, 2017

Hey BigJohnny - funny, I'm looking to do the same thing for my tank, with a mix of 400, 410, 420, and royal blue LEDs. All the "UV" led's (<430nm) have a max current of under 1,000mA, usually 700-800mA, so you'll need to drive them with a driver that won't blow them out by supplying too much current. As Mandelstam said, you need to know how many LED's at each current you are driving. There are some Meanwell drivers that supply 700mA, which is perfect for your UV Leds, such as:

https://www.rapidled.com/mean-well-lpc-35-700-constant-current-driver/

It lists you can drive 3-15 LED's at 700mA.

You could use the same driver for the xp-g3 royal blue LED's, but they will be brighter if you use a driver that puts more current out, because their max current is higher than the UV's, at 2000mA. So, you could use this driver if you wanted:

https://www.rapidled.com/mean-well-lpc-60-1400-constant-current-driver/

Best practice is not to drive LED's right up to their max current, so, for instance you would not drive 2000mA blue LED's like your's at 2000mA, which is why most people use a 1400mA driver like this for those. The drivers above are all non-dimming versions, but you can get dimming versions as well.

You can also check out ledsupply.com, which has a wider range of LED drivers.

Hope this helps. I'd be interested to see your final product, as I'm going to do something similar!

BigJohnny · Nov 18, 2017

Mandelstam said:
Here's a good article on the subject that I found. https://www.ledsupply.com/blog/understanding-led-drivers/

Before you can choose the driver you need to know a few things, how many leds are you using, their voltage, how are you going to power them, do you want to control them with a micro controller, etc, etc.

Thank you. Still a little overwhelmed but definitely know more now!

BigJohnny · Nov 18, 2017

ReefEco said:
Hey BigJohnny - funny, I'm looking to do the same thing for my tank, with a mix of 400, 410, 420, and royal blue LEDs. All the "UV" led's (<430nm) have a max current of under 1,000mA, usually 700-800mA, so you'll need to drive them with a driver that won't blow them out by supplying too much current. As Mandelstam said, you need to know how many LED's at each current you are driving. There are some Meanwell drivers that supply 700mA, which is perfect for your UV Leds, such as:

https://www.rapidled.com/mean-well-lpc-35-700-constant-current-driver/

It lists you can drive 3-15 LED's at 700mA.

You could use the same driver for the xp-g3 royal blue LED's, but they will be brighter if you use a driver that puts more current out, because their max current is higher than the UV's, at 2000mA. So, you could use this driver if you wanted:

https://www.rapidled.com/mean-well-lpc-60-1400-constant-current-driver/

Best practice is not to drive LED's right up to their max current, so, for instance you would not drive 2000mA blue LED's like your's at 2000mA, which is why most people use a 1400mA driver like this for those. The drivers above are all non-dimming versions, but you can get dimming versions as well.

You can also check out ledsupply.com, which has a wider range of LED drivers.

Hope this helps. I'd be interested to see your final product, as I'm going to do something similar!

It definitely helps. I may have to look elsewhere for drivers though because I'd like both channels to be dimmable so I can fine tune the look. Have you decided on drivers/leds/heatsink/etc yet?

ReefEco · Nov 20, 2017

I'll be getting my stuff from rapidled, and it will be a mix of 400-410, 410-420, 420-430, royal blue, blue, and warm white LEDs - basically for more punch in the low blue spectrum, bolstering the chlorophyll absorption peaks, plus some other blues and warm white for color pop/rendition. I have a bunch of drivers left over from previous builds, so will be reusing those - a mix of inventronics and meanwell drivers. Heatsinks from heatsinksusa.com, like you are doing.

For a 33" strip like you are wanting to do, you could easily just run two different drivers running 5-8 LED's each (like this one: https://www.rapidled.com/mean-well-eln-60-27d-dimmable-driver/ - just remember you will have to adjust the output current, depending on your LEDs), and then put a potentiometer (or hook up to various controllers) for dimming. For your heatsink, make sure to size it appropriately whether you are using passive or active cooling (fans or no fans).

For your application, two of the above drivers would work. One would be adjusted to ~700mA for your 420nm LEDs (max drive 80omA), then the other would be adjusted to about 1500mA for your royal blue LEDs (max drive 2000mA). Here's a video on how to adjust your driver to the correct current:

BigJohnny · Dec 2, 2017

@Mandelstam
@ReefEco

Well I caved and bought a 36" reebrite actinic blue xho during BRS black friday sale and boy is it a pretty fixture. Amazing how much smaller it is than my 21ledusa, but the mounting brackets/reputation is really what pushed me over the edge.

It looks extremely well designed/made and can't wait to fire it up and see the difference. Having said that, it doesn't come with a dimmer and I thought I could use my 21ledusa sunsetter module, but the size of the connectors is slightly different. I think I found adapters that will work but I wanted to ask you led guys on here to confirm that the dimmer will work properly.

Here is the power supply for the reefbrite, and here are the specs on the dimmer. The reefbrite is 24v max 4amps and the dimmer says 12-24v and max 4amps per channel, so I don't see why not........but I'm no expert. I did see that the dimmer premium aquatics sells for reefbrites (doesn't have the built in ramp/timer like my sunsetter does) is rated for 12-24v as well but 6a max. I really would prefer to use the sunsetter instead of buying another dimmer and a timer.

Thoughts?

Thanks!