All COB Users - Lettuce Grow Challenge!!

muleface

Well-Known Member
See my oasis cubes above?
That little trick having your oasis or rockwool cubes sitting on some perlite let's the roots grow out of the bottom of the cubes rather than being air-pruned. Then you just separate your cubes, shake the perlite off and drop them right on the bottom of your NFT channels :hump:
so i didn't have any perlite, but i do have vermiculite, so i filled a rectangular bin with it, dumped water on it and made a quick sand kinda mix, then i put my rock wool cubes on it. is it a big disaster, you bet, but the cubes seem to be sitting on top of it, so maybe it will work.
 

PicklesRus

Well-Known Member
so i didn't have any perlite, but i do have vermiculite, so i filled a rectangular bin with it, dumped water on it and made a quick sand kinda mix, then i put my rock wool cubes on it. is it a big disaster, you bet, but the cubes seem to be sitting on top of it, so maybe it will work.
I have a flood drain tray that has raised ridges. The trays sit ontop of the ridges but there is a little stagnant water in the valleys and the roots sit in there and soak it up. They are only fresh water seedlings though.
 

PicklesRus

Well-Known Member
The first lettuce grows I'm starting will be under my new fixture:

4 x Bridgelux EB Strips powered by a Meanwell HLG-120H-700a

A little disappointing, some of the LEDs (16 of them) between two of the bars aren't lighting up. The dark LEDs on the right are actually lit but a cord is hanging down blocking their view. If you notice I have a stepping spectrum of color, from 3500k in the back to 5700k in the front.

image.jpg image (1).jpg image (2).jpg
 

PicklesRus

Well-Known Member
was asking if the voltage of the driver was enough to light all the leds.
Ah, yeah it should be.

I should have tested them right out of the box, instead I mounted them to the heatsinks first so I don't know if it's something I did or if it's just faulty.

Weird though, they came in 2 foot boxes and were bent like a U shape. First I thought I got the wrong stuff until I opened the box.
 

PicklesRus

Well-Known Member
is that voltage issue? or is it bad leds?
Being that it's my first DIY build I can't help but think it was something I did wrong.
I emailed Bridgelux as I think Digikey just passes the warranty issues onto the customer.
Hopefully it works out for the better - warranty from Canada usually screws us over if something goes wrong I'll end up getting stuck with shipping charges more than just buying new strips.
 

PicklesRus

Well-Known Member
was asking if the voltage of the driver was enough to light all the leds.
The first time I powered it on, three strips came on immediately and one took a second to light up - it was missing 8 of the leds.
The next time I powered it on, two of them took a second to come on and one was missing 16 leds...

The wiring seems so simple, I don't know what went wrong.
 

muleface

Well-Known Member
as an IT guy, when something isn't working, i rip it down to the smallest amount of parts to get a positive result. So my first step would be disconnecting all the leds and running the driver to each one separately. yeah, it'll be a pain, but it will keep you from beating your head against the wall
 

PicklesRus

Well-Known Member
I'm thinking the same, but I can't run the LED on the driver by itself - the strips are 44.22v and the driver put outs a minimum of 107v I think, so I'm not sure what would happen if I did that but I dont think it would be good.

What I did do, was try removing all connectors from the DC circuit and wiring the strips directly to eachother. That didn't make a difference.

I have a multimeter, I would like to test the strips but I dont have a battery for my meter.
 

muleface

Well-Known Member
you have another driver you could test with?

I'm still pretty new at this too, but that driver seems undersized for this. Looks like the leds are 31 watts each, and driver is a 120w.
 
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PicklesRus

Well-Known Member
you have another driver you could test with?

I'm still pretty new at this too, but that driver seems undersized for this. Looks like the leds are 31 watts each, and driver is a 120w.
Strips:

44.2v @ .7A = 31w x 4 = 124W

44.2v * 4 = 176v, the driver says it will put out 215v @ .7a

215v @ .7a = 150w. I'm confused now.
The driver says 120w max, but how can it max at 120w when it's 215v @ .7 which is 150w....
 

PicklesRus

Well-Known Member
Strips:

44.2v @ .7A = 31w x 4 = 124W

44.2v * 4 = 176v, the driver says it will put out 215v @ .7a

215v @ .7a = 150w. I'm confused now.
The driver says 120w max, but how can it max at 120w when it's 215v @ .7 which is 150w....
The datasheets actually shows its rated at 150.5w
 

PicklesRus

Well-Known Member
you have another driver you could test with?

I'm still pretty new at this too, but that driver seems undersized for this. Looks like the leds are 31 watts each, and driver is a 120w.
I sized the driver by adding the forward voltage of the LEDs in series, that totalled 176v - I added a cree 336v cob to use up the rest of the space on it, but I haven't hooked that up yet.

It should work fine - I think the LEDs are damaged.
 

PicklesRus

Well-Known Member
I sized the driver by adding the forward voltage of the LEDs in series, that totalled 176v - I added a cree 336v cob to use up the rest of the space on it, but I haven't hooked that up yet.

It should work fine - I think the LEDs are damaged.
Hey so I contacted Digikey and they confirmed the strips were shipped incorrectly (bent instead of flat) so I'm getting a whole new set for free :cool:

I will get my multimeter to see how much voltage is left on my string now - I since have found a cheaper option for supplies in Canada here: Canadian LED component Suppliers and updated www.ledbuilder.org's quick links to show the Canadian shipping info.

Hey - I never asked, am I allowed to grow lettuce with strips, or is this a COB only kinda party? (Are the LEDs on strips technically miniature COBs?)
 
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