Build Your Own LED Grow Light

[Amy Gardner]

The watt meter reads 186 with the driver on full - but as this is draw from the wall I need to work out how that translates to power at the boards so I can use it to adjust things. I think I can do that with the info above. If not I’m just going to come back and request someone do yeh math for me!

That's easy

If you have 4 bds, that can max at at 60w/bd so that's 240w max they can run at, ish

And yer meter says yer running at 175w currently

175/240 = 72.9% of theoretically max

Excellent thansk Chris.

This is highlarious because literally what you describe there is exactly what I thought I was saying initially, in my first question m. So I already had the equation just maybe not expressing it very well bc of mixing up terminology (in my words not in my mind).

 

[DrDoob]

I believe what PGR said is the power supply isn’t 100% efficient, so if your wall meter says 175w your boards may be only getting 150w or so. But I’m high and could’ve read it wrong.

 

[Amy Gardner]

So 5 boards rated at max 60watts each, is max 300W (ish)

The driver maxes out at 200W.

So that’s 66% (ish)

And then I need to factor in the efficiency thing, like Doob says there.

Except I think it works a bit differently to what Doob said.

With the driver on full it pulls 186 from the wall according to the meter. It’s tempting to think this is already accounting for the 94% efficiency - because the max out put if the driver is 200 and 186 is about 94% of that (93% ish, actually). But then I’d be making the mistake of conflating draw from the wall with driver output again - and I’m almost back where I started.

At the very least I now understand that this driver cannot power the boards harder than about 65%. I wonder if that’s a problem considering all the extra diodes I have. I know Graytail runs his like this and his garden doesn’t lie. By his reports the lower nugs on his plants are way denser under this kind of set up than they have ever been.

I’ll at least be fully confident to crank it at max during flower

And I am getting a better understanding what I have going on with my set up, thansk everyone.

 

[Amy Gardner]

I believe what PGR said is the power supply isn’t 100% efficient, so if your wall meter says 175w your boards may be only getting 150w or so. But I’m high and could’ve read it wrong.

Except I think it works a bit differently to what Doob said.

Ok been re-watching some LED gardener and what you say is right Doob.

So that means my driver doesn’t pull its full 200watts from the wall. On full it’s pulling 186, so PGR’s estimate that I’m getting about 166W to the boards is about right.

Finally getting it. I’m bummed and a bit confused that the driver isn’t able to pull the full 200watts ...

 

[Chris Scorpio]

Ok been re-watching some LED gardener and what you say is right Doob.

So that means my driver doesn’t pull its full 200watts from the wall. On full it’s pulling 186, so PGR’s estimate that I’m getting about 166W to the boards is about right.

Finally getting it. I’m bummed and a bit confused that the driver isn’t able to pull the full 200watts ...

Do you know the max mAh it is supposed to have, the bd not driver

I'd say the 700ma is too low

 

[Amy Gardner]

the max mAh it is supposed to have, the bd not driver

its 1.2A

 

[PurpleGunRack]

All right it has already gone outta hand here, let's start clearing up a bit

ALL boards and drivers WATT ratings are DC, NOT the watt you draw from the wall (AC)

You ALWAYS pull MORE power from the wall than you put into your boards!
Picture: The driver takes a cut to translate AC to DC.



@Amy Gardner What boards are you using ?

I think you might have nominal and max mixed up, 1,2 ampere max seems like a very low max....

Actually, I'm 99,99% sure you've got them mixed up -> 640 diodes running at less than 200w , I run my 352 diode lamps at 200w and my QB288 V1 at 135w.

I believe what PGR said is the power supply isn’t 100% efficient, so if your wall meter says 175w your boards may be only getting 150w or so. But I’m high and could’ve read it wrong.

You're right

It's not that big a difference though, when using HLG drivers we rarely dip below 90% driver efficiency.

With the driver on full it pulls 186 from the wall according to the meter. It’s tempting to think this is already accounting for the 94% efficiency - because the max out put if the driver is 200 and 186 is about 94% of that (93% ish, actually). But then I’d be making the mistake of conflating draw from the wall with driver output again - and I’m almost back where I started.

This is a great example of why it's so hard to calculate these things on paper

My guess of 167w was based on LOWER voltage than the boards max rating going to the boards, but it's the other way around here, your boards get a HIGHER voltage than the max rating.
Since I've already arrogantly established that 48V and 1,2A are the nominal ratings, it makes a little sense to me that the voltage is higher than 48V, now I'm thinking your boards are more likely ~54V and maybe as much as 3,0A max

So that means my driver doesn’t pull its full 200watts from the wall. On full it’s pulling 186, so PGR’s estimate that I’m getting about 166W to the boards is about right.

That was just my guesstimate of the actual wattage based on the max ratings and how lower current usually means you get lower voltage than max, but if the max rating really is the nominal rating the equation becomes false


If you pull 186w from the wall, the boards get: 186w AC * 0,94% driver efficiency = 174,84w DC

175w DC / 5 boards = 35w DC per board

35w DC / 0,7A = 50V per board

Now we've established that you can put a max of 50V and 0,7A (or 35w DC) into each board with the driver you have.


35w DC * 1,06 = 37,1w AC per board (37,1w * 5 boards = 185,5w)



To calulate percentages we need the actual V and A max ratings on your boards

 

[Amy Gardner]

Ok the numbers I gave originally for the boards were:
48V and amperage range of .48-1.2A
As I said when I first posted them, those numbers are from the manufacturer and I feels a bit wired that you’d assume that I just got that wrong

ALL boards and drivers WATT ratings are DC, NOT the watt you draw from the wall (AC)

Yes I did get that from your earlier post

You ALWAYS pull MORE power from the wall than you put into your boards!

and I got that too!

I’m sure I understood your earlier infor better that you think I did - and my problem is in the execution

So those equations you’ve posted there are all very helpful.
I can run them again now with the right numbers

Thanks for taking the time

 

[PurpleGunRack]

A few months ago I randomly bought 4 HLG QB132 Quantum Boards and a HLG-185H-C1400B not totally sure why I bought this combo but I’m sure I read it was good somewhere.

I don’t know the difference between a watt and an amp, but I think these lights could support up to 300w and this power supply only supports up to 200w. So I think I can’t really crank it to up 11 but am running efficiently? It seems like plenty of light for my 2’x2’ tent so I’m happy, just wish I could do math.

I made the frame from some used openbeam kit I found out in the garage. It’s about as Frankenstein as it gets but seems to be functional.

From HLG's website: 36V DC. Max current 2000mA

288w DC is their max and your driver can give them 200,2w DC

Your driver puts out 1400mA, and is 1V short of the combined max V of the boards.

69,5% of max rating, that's just fine especially with that many diodes, no need to look for a driver with higher A output, and the next step of HLG series driver is probably 2100mA.

When running boards with out heatsink, it's important to stay below the max temperature, and in all applications it's recommended to stay below the nominal/performance temperature.

 

[PurpleGunRack]

Ok the numbers I gave originally for the boards were:
48V and amperage range of .48-1.2A
As I said when I first posted them, those numbers are from the manufacturer and I feels a bit wired that you’d assume that I just got that wrong

I'm not assuming you got them wrong
Often the manufacturer is putting the wrong specs on or mixing up nominal and max, or basing a max w on nominal V and A etc.
They like to keep their ratings on the low side rather than the high side, if you fry a unit at lower than max rating they're in a world of legal shit and have to recall the entire batch.

We've ascertained, without any doubt, that you actually put 50V into your boards at lower than max A rating, so a max rating of 48V is physically impossible.

What model are the boards?

 

[Amy Gardner]

They’re boards that Graytail designed himself. So I just PM’d him to double check that the numbers I got from the manufacturer are good.

I’m runnIng them close to the way he runs his, which is the aiming for efficiency thing. (Why I was curious about the conversation about that, which started all of this).

I’ll wait till he gets back to me and report back.

 

[PurpleGunRack]

Ahh ok, that changes it up a bit, do you know what diodes they use?

I just assumed it was Samsung LM561c/LM301b in which case 640 diodes running at 186w is quite low.

Still a discrepancy in the V and/or A max rating though, if you get 50V at 0,7A you should get higher V at 1,2A...

 

[Amy Gardner]

Yes they are! The LM561c

 

[PurpleGunRack]

Yes they are! The LM561c

OK, that's good

They're running without heatsinks, right?

 

[Amy Gardner]

without heatsinks, right?

 

[PurpleGunRack]

Keep on keeping on


(or get some heatsink and a HLG 240h -48A )

 

[Amy Gardner]

OK so I went back and spent some time with my notes and confirmed my specs etc.
I was confused by your talk about the voltage yesterday because one of the early things I learnt is that voltage requirement drops when you run a board at lower current. This I learned from LED Gardener - he runs a demo in one of his vids with a multi meter and a constant current that shows how voltage drops when lower current goes to the board.

My boards are definitely 48V: the diodes are 3volts maximum with 16 in each series making 48volts, which varies according to current (43-46 at lower current).

I can also confirm, again , that they are 480ma to 1200ma. Apparently I could run them as crazily high as 1600ma with really good heatsinks, but I’m happy running for efficiency at the moment and I’m seeing amazing results out of other gardens running their boards this way.

This conversation has helped me get a better handle on what I’m doing with them so that’s been a good catalyst for pushing me to the next level of understanding. I think that now I could almost work out my own setup when I need to upgrade it a bit (with some nice new Samsung strips ).

I also understand why folks criticise the efficiency approach which was the question that started this conversation - I was wondering why. I understand why now so that’s good and I think I’m comfortable with the efficiency (not to mention the lack of heat!). Undersatnding is good.

And while from some perspectives 700ma from the driver may seem too low, I do have almost 50% more diodes than I need for the space

 

[Pennywise]

The boards are great for efficiency, I tend to run mine at 100% it raise the lights up for better penetration. The higher the light the broader the light spreads out penetrating a little deeper.

 

[Chris Scorpio]

I really think the biggest challenge us diy QB people face is the correct driver for your bds

Correct watts and Ma for the correct bds

Many of us have learned the hard way

I like the option if running my lights, again my choice, at 110% or max the bds can take, again, if I want to

Hated only getting maybe 70% from mine originally because I got the wrong driver

 

[Mayne]

The boards are great for efficiency, I tend to run mine at 100% it raise the lights up for better penetration. The higher the light the broader the light spreads out penetrating a little deeper.

optical illusion,