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# Need help with DIY LED GROW LIGHT Answered

Hello people, i have never made led light before. i bought 3w led chips from ebay. 3 colors. red, deep red and royal blue. also bought led drivers 100w. i wired led-s by google)) and twhen connected this driver they dont turn on . i tried 1 led and of course it burned on this driver but when trying more leds it doesnt light up at all. what is the problem? can anybody help me? thank you

## Discussions

i tried 5 3w leds , 2 leds too but nothing. everything i have connected good. i dont understand the problem :(

What voltage do you get with no leds connected, ie free running volts.

What to the hieroglyphics on your LED driver say? In particular I am interested in the scribbles next to the glyph labeled "OUTPUT".

From the picture it kind of looks like it says:

DC: 27 - 38 V
DC: 3000 mA +or- 5%

By the way, the usual way LEDs are powered, is by pushing a constant current through them.

It looks to me like, for the driver you have shown us, this driver tries to keep its output current at a value close to I = 3000 mA = 3.0 A, and the, "+or- 5%", is a measure of how closely it can achieve this goal.

It turns out this is too much current for your 3W LEDs, and the reason I know this to be true, is if I multiply a current of 3.0 A, by a typical LED voltage, like 2 to 3 volts, I get 6 to 9 watts, which is twice to three times the, 3W, power rating of the LED.

So, I think that is your main problem; i.e. you picked a LED driver that drives with more current than your LEDs can take. I suggest next time, choose one that has a constant current output of around 1.0 A = 1000 mA, or maybe get one that is adjustable over a range of current, like for example, from 0 to 2000 mA.

I mean, for a driver with adjustable output current, it comes with a little knob on it you can turn, for to adjust the output current.

My other recommendation is to get a some resistors that could be used as test loads for setting up your LED drivers for the first time. I mean, what I have in mind, are resistors sized at around 1, 2, or 5 ohms, with power rating of about 10 watts each. That way you could string a bunch of these resistors in series, and give your driver something to push current through, without risk of overcurrenting the LEDs. The idea here is that you could test the driver on some components that will dissipate the same amount of power, but that are cheaper, and harder to kill by overcurrenting them.

This idea might be more applicable to an adjustable current driver. That is to say, you use the test load, made of resistors, for to set the output current where you want it. Then connect the driver to your actual load, which is a series string of LEDs.

How many leds in series with 1 driver?

I used 10 X 3W grow leds on the driver pictured and its still going strong after 3 years.

Total of 30 leds shared equally on 3 drivers.