# Led Grow Light

#### TomatoMan

Joined Oct 16, 2011
39
Hello the question I would like to ask is about wiring and powering a grow light. The light I am building will be made up of 3watt high power leds. I will be surface mounting these to a sheet of aluminum. I searched the other grow light post here but did not find one that would answr my questions. I will be using 50 red 2.6-3 volts, 10 blue 3.6-4 volts, 5 cool white 3.4-3.6 volts, and 5 warm white 3.4-3.6 volts. I am a total noob about Leds and would like to know the best way to wire them. Should I keep all teh red in one series and blue in its own ect? Also what should I use for a power supply for this light? Thanks for any help you people can give.

#### Wendy

Joined Mar 24, 2008
22,428
The subject has come up quite a few times here on AAC. I have helped with several projects, but no two are quite the same.

Since you are dealing with power LEDs you MUST mount them to a heat sink, a chunk of aluminum to soak the heat generated by the LEDs away. This is critical.

The second thing you need to work on is to find a power supply that will drive all those LEDs. You can use a 12V power supply, I believe a 24V is better. It needs to be very beefy. You quote 50 red LEDs, that means it is going to have to be larger than usual, that or you're going to need multiple power supplies. You will likely need around 250-300W of power. Power is volts X amps.

After you have a power supply picked out I can help you design something to drive the LEDs. You will likely have to build some electronics, there really isn't a way around this, but it will be relatively simple. You will also need a DVM.

I am not in front of my computer, when I am I will point you to some other thread. The reason is there has been a lot of discussion about what the best color mix of LEDs to use. I suspect you will be interested in the subject, you are not the first person (or the 10th) to come to this site to discuss the subject. Your's sounds like the biggest to date however.

By the Way, Welcome to AAC!

#### Wendy

Joined Mar 24, 2008
22,428

#### iONic

Joined Nov 16, 2007
1,654
The Supply I pointed to is just one of many that this supplier has. The specs are:
Output: 28Vdc / 9.0A. (unrestricted convection cooling) or 28Vdc / 12.5A (26CFM forced-air cooling)

The power is between 250W - 350W depending on the addition of sufficient cooling. And even if you did use fan cooling I would not push it past 300W.

#### Wendy

Joined Mar 24, 2008
22,428
Looking at it the Reef LED power supply would be ideal for your application, if it has enough outputs.

One of the things we often do here is point out off the shelf solutions. Your application is a bit larger than most, so it is likely you would need more than one of the units, even with one that can drive 40 or so LEDs. My suggestion is to contact the company and ask.

If you decide to DIY the power supply shown in post #6 is ideal. It will be much cheaper to build it yourself, but it will get very hot. The other companies probably doesn't.

There are types of circuits we do not allow on this site. Without knowing for sure the aquarium companies drivers probably come under that heading.

#### mcgyvr

Joined Oct 15, 2009
5,394
2 BIG differences in the supplies I posted versus iONic's..
Mine are "constant current" supplies specifically for LED's versus he posted "constant voltage" supplies.. Before you go any further you MUST know the difference.

#### TomatoMan

Joined Oct 16, 2011
39
I will need a constant current power supply per Manufacturer's specs. I looked over some of the drivers at the site you posted mcgyver not sure whcih I would need. The prices at the site seemed a little higher it looked like the one for my needs could run well over 100.00. Mcgyver did you look at teh ebay link I posted? Do you think the drivers at the reef site far exceed the one on the ebay listing? I am have been working on a hybred tomato for the past year using outside growing and inside HPS in the off season. The HPS was putting out to much heat my plants were not happy. I am very close with my cross have the appearence but wrong taste at this point. That being said if I succeed I may have to name the variety after one of you LOL.

#### iONic

Joined Nov 16, 2007
1,654
TomatoMan,

What's the (If) Typical Forward Current for these LED's???

#### TomatoMan

Joined Oct 16, 2011
39
ionic led supplier stated 750mA on all four colors Blue, Cool white,Warm white are 3.0-3.6V and the red is 2.6-3.0 volts

#### mcgyvr

Joined Oct 15, 2009
5,394
Mcgyver did you look at teh ebay link I posted? Do you think the drivers at the reef site far exceed the one on the ebay listing?
yes its a constant voltage supply. which won't work without additional current limiting circuitry. Meanwell drivers are EXCELLENT quality. I use 2 at home on my reef setup (2 x ELN-60-48D).
The link I showed has multiple variations and lists which meanwell you will need to use. I believe your needs fit into one of those options.

Quick answer is I would use 2 x PLN 100-48 and do the second to the last wiring configuration (twice) splitting your light into 2 circuits essentially.

#### Wendy

Joined Mar 24, 2008
22,428
yes its a constant voltage supply. which won't work without additional current limiting circuitry. Meanwell drivers are EXCELLENT quality. I use 2 at home on my reef setup (2 x ELN-60-48D).
The link I showed has multiple variations and lists which meanwell you will need to use. I believe your needs fit into one of those options.

Quick answer is I would use 2 x PLN 100-48 and do the second to the last wiring configuration (twice) splitting your light into 2 circuits essentially.
Have you used their stuff before?

#### mcgyvr

Joined Oct 15, 2009
5,394

#### Wendy

Joined Mar 24, 2008
22,428
Never mind, I see where you stated you did.

#### TomatoMan

Joined Oct 16, 2011
39
Mcgyver I checked out the Mean Well driver at 68.00 each I would be at 140 in drivers. I was wondering if there may be a cheaper option at this point. Again I thank you guys for all the help

#### Wendy

Joined Mar 24, 2008
22,428
Depends on how much your personal time is worth.

Advantages with the Mean Well driver:

1. They are much cooler. There will not be any waste heat to get rid of. I can not speak as to their effectiveness, if I used them I would still have a lot of questions to answer.

2. They are simple. This may be a big advantage if you haven't done an electronic project before.

1. They are expensive. In spite of the diagrams they provided there is some question how many 3W LEDs per unit can be driven by one. If it turns out to be less than we originally thought then the price can go way up.

Because of this this it is worth asking lots of questions before buying any merchandise. Call the manufacturer, tell them what you are doing, and see what they recommend.

1. It will be cheaper. Maybe a lot cheaper. I guestimate around \$40, maybe more, but not a lot.