looking to try DIY LED. quesiton about driver boxes.

in order to light up 288 REAL 3w bulbs, do you need 900w of driver? and whats that equal out to in terms of actual voltage being used? 900 or less? cause im always seeing LEDs draw less Watts then advertised but thats how they work correct? any help is appreciated. thanks

It's not all about voltage.
Power (P) = Voltage (V) X Current (I)
P is measured in Watts (Joules/second), I in Amperes.
That energy is not all converted into light, a large proportion is turned into heat.
This heat creates an inefficiency in LEDs which becomes detrimental at higher Power (commonly referred to as "LED Droop" IIRC)

http://news.sciencemag.org/sciencenow/2012/05/how-leds-got-their-shine-back.html

Zhao's group obtained a special substrate from Mitsubishi Chemical Corporation. This substrate, itself made of gallium nitride, encouraged the gallium nitride diodes to grow in a very specific crystalline orientation, close to but different than the polar orientation usually used. It eliminated most of the unwanted electric field. Other teams have made diodes with a nonpolar and semipolar orientation, but none of them have been as successful at reducing droop. Zhao's team created a blue LED with a peak efficiency of 52% at 20 mA. Even when the current is increased by 10 times that, the efficiency drops by less than 14%. A typical LED would lose more than 60% of its efficiency with that much current pumping through it. The team will present its research on 10 May at the Conference on Lasers and Electro-Optics in San Jose.

Click to expand...

http://www.digikey.com/us/en/techzone/lighting/resources/articles/identifying-the-causes-of-led-efficiency-droop.html


Now I haven't been keeping up to date with the latest research, so I suppose the better person to ask would be StarDustSailor or one of the other "techier" people on here.
However, to make a winding story more concise, that is one reason why LEDs are not driven at maximum.
And no, you don't need 900 Watts to drive that many.

Nah, you don't need 900W, you'd melt your LED's. Assuming you drive the LED's at 650mA, and also assuming average voltage drop is 2.5V per LED (reaaaally rough asumptions):

2.5V x 288 = 720V

720V x .65A = 468W

So you're probably looking at ~400-500W depending on the LED's used and how you choose to drive them.

Again, though, these are really rough estimates derived from the information given. I could be wrong, people may chime in, but I advise you to either head over to the ICMag LED forum, or use the search function here to find info on building your own panel (there are some really good threads). I love the community here (best English speaking LED grow forum I can find!), but those ICMag guys seem to have no problem walking newbies through making their own LED panels, whereas here we tend to leave ya alone/meet up on the other side of the swamp once you've built your panel and have plants under it. Sort of tough love attitude, ime.

Good luck!

Well, this link will be helpful to better understand the LED actual watts.
http://singledgrowlight.blog.com/2012/04/09/apollo-led-grow-light-how-to-calculate-its-actual-power/

Are all of your LEDs to be driven at the same amperage? Some colors tend to want more amperage than others (to be efficiently driven)....for example one would often find royal blue driven at 1000mA whereas say 630NM red might be driven at 700mA. What do the spec sheet(s) for your LEDs say? The Voltage forward (Vsubf) for each LED would be different varying with the amperage that you are driving it at.

As Bumping described above - 650mA might have a 2.5V forward drop but if you drive that same LED at 700mA then the forward voltage drop might increase to say 2.7V forward. You usually want to drive an LED at something like 60 - 70% of max amperage with more heat management being needed and higher voltage power supply needed as well for higher amperage drivers.

Heat management (good heatsink, mpcbs, thermal pads, fans, etc) is crucial for light ouput on spectrum and the life of the LED so give that part plenty of consideration.

So do I need different drivers for different colors if they require different amps?

Dirty jersey said:

So do I need different drivers for different colors if they require different amps?

Click to expand...

That's your choice as the designer but ideally one would run each color as efficiently as possible...but that costs money...so it's your choice about how ideal you wish to be. I have tried to use drivers to maximize efficiency for each color.

Another design consideration - do you want to be able to dim the light? Some drivers are dimmable with a simple potentiometer (depends on the driver) so you can run a color from just about nothing to max of the driver. Why would you want to do that? Well, you might have a multi-color panel and not want your 660nm red to be very dominant during veg but do want to dial it up for flower...or maybe you want to use the same panel for the whole grow and want to dial back the amount of light for seedlings...or...

...just design thoughts and not meant to be daunting. You may or may not want dimming but with some drivers - like inventronics - you can add it easily with a pot and a couple of soldered wires....but you definitely don't need it....and in the case of inventronics (if you purchase a dimmable driver to start with) you could always add it easily later if you eventually decided that you wanted it.

Sort of tough love attitude, ime.

Only for the brave ....