How do I power my LED's?

I posted before with unknown specs on the lights, but I now have the specs.

I have 50 Red LED's and 20 Blue LED's that I would like to make in an array for a grow light. I was thinking about gluing them with thermal glue on flat aluminum bars that are 2 inches wide in a rectangle with about 1 inch spaces around them because I don't have heat sinks. I think they would be able to dissipate enough heat if I use them in conjunction with a fan.

Here are the specs for the red lights (50):

2.4mV forward current
700mA

blue lights (20):
3.2mV forward current
700mA

If I'm correct, I need 84 watts for the Red LED's altogether; 44.8 watts for the Blue LED's altogether: combined wattage of 128.8 watts.

Previously, I stated that these lights were 3w, each. But I would rather save life on the diodes and run them at this lower power because they still give off a great amount of lumens.

Can anyone give me some directions on how I would construct this array? (what drivers to use, how to wire the LED's together, and how I could make the system plug into my wall outlet (standard USA socket)).

THANKS!



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lemonie6 years ago

If you were thinking of 12V:
10 x 5 red in series = 7A, 84W
6 x 3 blue in series = 4.2A, 50W

Is that right?

L

ammakrom (author)  lemonie6 years ago
Let me see if I've finally figured it out.

If i found a 12v power adapter at wal-mart, I could run that 12V to 10 parallel circuits that each have 5 red LEDs in a series. Since the voltage drop is 2.4v per LED for the reds, they would add up to be 12V total across each string. So I wouldn't need a resistor or anything and each series would be getting 12V.

I think that's right? Correct me if I'm wrong, please.

That sounds right, but you need one that'll give you the 7A.
But these high power things may need a driver - people like steve' know better than me on these things.

L
ammakrom (author)  lemonie6 years ago
I'm so lost haha. Thanks for everyone's help. I think I'm just going to put the LEDs in my closet and forget about it all. I guess I'll just go and buy a HPS light, instead of trying to be cool and build an LED grow light. haha
Run them in series, run them right, and they'll last well over 50,000 hours.
frollard6 years ago
You can't run high power leds totally in parallel - there isn't a high enough current low voltage source in existance.

Were the answers to your question last time not sufficient?
You shouldn't run them in parallel anyway.
Agreed, but if you look at most power leds - they are already internal matricies of seris/parallel diodes - granted they're manufactured to be identical in that sense...

Agreed, without limiting, try to avoid parallel.
Yes, but the big A%^ matrix types are ALSO on a high conductivity backing, so they are close to isothermal.

Steve
true! Any runaway would simply heat its neighbors and keep them in check :D It's nice having engineer folk around, I Just pretend to know everything!
I know this isn't an answer but can someone make an Instructables for this so many people ask similar questions about LED's? I don't know enough to make one myself.
2hot2hack6 years ago
hey mango to you tube and type in 200wat led torch that will hellp you