Help needed for Mono grow light. Or for the calculations of LDDs and power supply

Hey everyone, I'm building a grow light using monos, Before anyone else tells me I should use COBs, I was not aware of them pre me buying these mono diodes. I will be incorporating some 3590s or 3070s on my light but for now I want to talk about a unit with just Monos.

I just want to check I understand what I need to drive them.
So far the idea would be to use a mixture of spectrums which total 120x 5w diodes.
The monos are all 1000mA max current which I plan to run at 700mA.
If I understand right I am adding up the total forward voltage which would be 680.4 VF ?
If I multiply that VF by the amps I get the total wattage (draw)

So 680.4 X 700mA = 476.28watts?

I plan to drive these using these Mean well LDD-700H dc dc led driver 700mA
because they have the biggest output voltage, 2-52v so I can use less LDDs to drive all strings.
Am I correct in thinking that having a VF of 680.4 I can divide that by 52v = 13.0846, so I would use 14?

here is a link with the detailed specs of this LDD-700h
http://nuohan.en.alibaba.com/product/1555849827-215686700/Mean_well_LDD_700H_dc_dc_led_driver_700mA.html?spm=a2700.7803228.1998738836.185.wBgkAX

Next I would want a power supply to power these.. I am looking at 2x 350w which would be more than enough? This is what I was looking at..Mean Well LRS-350-48 Single Output Switching Power Supply
Here is a link with specs
http://nuohan.en.alibaba.com/product/60301897916-801096942/Mean_Well_LRS_350_48_Single_Output_Switching_Power_Supply.html?spm=a2700.7803228.1998738840.10.wBgkAX

So would two of these pair with 14x LDD-700h to power them?

I have to point out that obviously the different diodes have different VF so I am using this as an example calculation to make sure I'm using the right numbers. The exact calculation of number of LDDs may be different once I work out each string of each nm range. I just didn't want to go that far if I were adding, multiplying or dividing the wrong numbers. I assume all diodes per string must be equal in VF, a string of 4.6 a string of 6.8 ect..

An example, the 660nm reds have a VF of 4.6, to use 48 diodes would make 220.8VF so divided by 52v I would need 4.24 so 5x LDD-700h for the reds running 11 per string in series?


Am I correct in the way I'm working this out or am I miles away or using the wrong values entirely??
I would appreciate anyones advice who knows the crack to point out my errors.
As I stated I already own the LEDs, I also have some heat sinks. This will be my next purchase and I don't want to take the word of any sales person I'm purchasing from. I will probably buy some of those LDD boards from rapidled to make a neater job with less soldering.
Sorry if my post is a bit of a mess, it reflects my mind. You should see my notes!! I cant make sense of them and I wrote them.

Cheers for any input folks. @SupraSPL @Growmau5 @Anybody else with the knowledge of an LED guru
C.W

When you go calculate amps-

1 amp=1000mA
1 mA=1/1000 amps

Double check your fV figure, 680 doesn't sound right.. example

8 unknown leds in series draw 3.5V each at 700mA (or 0.7amperes),

The total voltage equals the sum of volts used from all load sources, so 3.5 x 8=28V

This means each led would draw ~2.45w=3.5 x 0.7, and that you would need to source a constant current power supply that provides around 28V at 700mA, so a source with a range of 15-30V would be perfect for this example.

I like the LRS and the 350 is what I SHOULD have gotten instead of the 150 (live and learn).
What you are missing is... it puts out 48v and when you pass that to the LDD units there is a voltage drop of 5v or so.
Now the LDD will accommodate as many little LEDs as you want up to the 42v or so at constant current 700mA.
You can't use 52v in your calculations because to get that you need a 56v (max input voltage for LDD) supply.
The LRS-350-48 puts out 7.3A max so you could only run 10 LDD units at 700mA.
(Edit: forgot that part - 10x700mA for 7A )

I've only done COB off LDD drivers, but hope that helps with your calculations.
Doesn't matter what you put on a LDD (provided over the minimum voltage out) it will give whatever voltage you want but will keep the current flowing at that 700mA level unless you put in a PWM dimmer. Even then it still pumps it out at same current but turns them off/on really really fast and give the appearance of being lower light level (voltage & current remain the same).

Thanks @Scotch089
the diodes I have are as follows.
660nm @4.4-4.6fV X48 using highest value =220.8
630nm @4.6-4.9fV X12 =58.8
620nm @5.2-5.4fV X12 =64.8
445nm @7.0-7.2fV X24 =172.8
3000k @6.4-6.8fV X12 =81.6
4500k @6.4-6.8fV X12 =81.6
total = 680.4v
total watts= 476.28w ......
Cheers Scotch, I will re look at working out those wattages that way round in a moment.

@HalfBee The LDD I linked does say the input range is from 9-56VDC and the output range is 2-52VDC below it says 97% efficiency so is that what you mean, taking off the 3%+ it would then be 48VDC. Thanks for pointing that out. So I will need more than I thought overall, running a diode less per LDD. Awesome.
Also so your saying I could have a mixed bunch of different fV on the same string and it will run them all at the V needed as long as the current for all is the same, which it is. As in I could have a string of a few 660nm @ 4.6fV with a few [email protected] all running at 700mA?
Again, cheers both of you.

No... what I said was...
The LRS ONLY puts out 48v - That is all you can give the LDD for input.
What comes out of the LDD is less than 48v probably by that 3% or such (not sure where I read about the drop in voltage by using the LDDs but know it has to be factored into output equation).

HalfBee said:

No... what I said was...
The LRS ONLY puts out 48v - That is all you can give the LDD for input.
What comes out of the LDD is less than 48v probably by that 3% or such (not sure where I read about the drop in voltage by using the LDDs but know it has to be factored into output equation).

Click to expand...

Cheers.. I'm good at misreading stuff! thanks for clearing that up. Looks like I was reading the 52.8v from the voltage adjustment range

Originally I was looking at the SE-350 and that has an adjustment range of 41-56v The company I was speaking to recommended the LRS as a more economical option. But since my watts are only going to be 476.28w I can start looking at 2x a smaller power supply which may be cheaper still. I'm not even sure why I wanted 2x 350w when they do lots more options.

Yeah, you could adjust it upward and overdrive the LRS up to 52v, but that would make it run hotter. But at 48v it runs rock steady. They are cheap enough to not have to push them. Could go 350 and a 150 (LRS-150-48 puts out 3.3A so you'd only get 4 of the 700mA on that one). Hope you get it worked out, interested in seeing what you wind up with...

HalfBee said:

Yeah, you could adjust it upward and overdrive the LRS up to 52v, but that would make it run hotter. But at 48v it runs rock steady. They are cheap enough to not have to push them. Could go 350 and a 150 (LRS-150-48 puts out 3.3A so you'd only get 4 of the 700mA on that one). Hope you get it worked out, interested in seeing what you wind up with...

Click to expand...

Thanks, I am just looking through the full range now. It seems a lot of the lower Watt units don't have the 48v so I will ponder on it. Appreciate your advice, I don't want to push anything too hot. The LRS 350s are only about $20 as apposed to the SE which were $36. In my country they are a hell of a lot more than that. The LDDs are only $3.40 each, they are double that from somewhere local.

EDIT I have found some good calculation examples on rapidled so I will rework all my calculations out for each string. http://menarilighting.com/rapidled/documentation/LDD-H-4 Board.pdf

Right I have reworked my calculations to take into account the fact that the LRS will put out 48v into the LDD-h-700s which will then lose a further 3v giving me 45v per LDD.
Working out the max LEDs available per string and the Vdrop for each.
I can have 9x 660nm per string so need 6 strings
9x 630nm 2 strings
8x 620nm 2 strings
6x 445nm 4 strings
6x whites 4 strings

So I need 18 LDD-h-700s
total Vdrop across all strings=759v X 0.7 = Total watts of 531.3w

I hope I'm right with those numbers.
Again thanks for the assistance folks
Ah shit, I have made the assumption that I am using maximum LEDs per string which I am not, that would total 136 diodes and I'm using 120....
Think I will just max them now I have typed that... I'm running out of note paper!!

EDIT
Actual Vdrop= 680.4v
Total Watts 476.28w as originally calculated

This is a partial list of 48v meanwell power supplies (and pricing at that time)
As you can see as you move up in Watts the higher the price (and more Amps they can drive)
There are more, but I was bargain hunting and something like the HEP series is way over the top but designed to operated in harsh environments and you get what you pay for...

Thanks @HalfBee There are some seriously expensive power supplies!
I have been reading through some pdfs on rapidled about how many LDD-700h I can power through the LRS-350-48
I cant see anywhere were it says the amps limit the amount, There are calculations to figure out how many watts you can have per string and how many watts per driver but nothing on the amps. Is it as simple as a 7.3Amp power supply can provide 700mA to 10 LDDs or am I been thick?

No.. that is exactly right... 7.3A powers up 10 @ 700mA (with 300mA to spare)
With their 4Up boards that's 2 full boards plus 1 extra with only 2 LDD 700 on it (and a 300 if you fancy it)
Or you can order a 5Up board for different source and get by with 2 boards for the LDDs.

Don't sweat getting every drop of juice from them... keep it simple...

HalfBee said:

No.. that is exactly right... 7.3A powers up 10 @ 700mA (with 300mA to spare)
With their 4Up boards that's 2 full boards plus 1 extra with only 2 LDD 700 on it (and a 300 if you fancy it)
Or you can order a 5Up board for different source and get by with 2 boards for the LDDs.

Don't sweat getting every drop of juice from them... keep it simple...

Click to expand...

Awesome! So I can run 2x LRS-350s each powering 9 LDDs and everything will be dandy. That seems like the best value and they have them in stock so i can order early this week.
I'm glad you brought up the 5Up boards, I wouldn't of known about those. I will have a search now and see where I can get them. This is all starting to make a bit more sense to me. Although I'm sure I will continue to use the wrong terms here or there.
You've been a real help HalfBee. Cheers!