Proposed COB DIY Build - Advice sought from DIY EXPERTS

[Mazoz]

Hi All


So after days (yes days) of searching I have found a combination that may work. Mind you i have only tackled the COBS and the driver. I'll wrap my head around heat management later.

I was hoping that the more experienced DIY LEDers could give me some advice on the following proposed light build:

I have selected the following COB:

https://www.digikey.co.za/product-detail/en/BXRC-40E4000-C-73/976-1430-ND/6152440

I will purchase six of these COBS



I have selected the following driver to run it:

https://www.digikey.co.za/product-detail/en/HLG-320H-C1400B/1866-2500-ND/7704058

What do you guys think? By my calculation each COB should output 47.74 watts per a COB for a total output of 286.44 watts.

By my calculation the Driver I have selected will run six of the COBS no problem and leave me with 24 v to play with? Can i scavenge the remaining volts from the driver to run a fan?

Are my calculations correct? And will this be able to grow 2/3 plants through a full cycle? Bear in mind I am very financially constrained and this is the best I can do on my proposed budget for parts. I

 

[Chip Green]

Are my calculations correct?

You have correct calculations.

 

[Mazoz]

You have correct calculations.

Yay!!!

Will this work 12 sq ft area? How many plants could I do with it?

 

[mahiluana]

Can i scavenge the remaining volts from the driver to run a fan?

i wouldn`t mix up leds and fans in a row !!!
- if you want to fill up the remaining volts up to max. open circuit voltage,
i recommend to add 4 x 10W chip in a warmw. spectrum,
to get some reds into your 4000K led build - for blooming.

Any chip with i.e. Vf = ~12V and can stand 1000mA is fine // 2 in series 2 parallel helps to reach full load of 320W.
Parallel to a 10W chip you then may try, to drive a 12V fan, if he is made to work in a 500mA range.(6W)

You have to fix all on a heatsink able to sink ~240W of heat.

may be you are also interested how to wire chips in a row without wires

 

[Mazoz]

i wouldn`t mix up leds and fans in a row !!!
- if you want to fill up the remaining volts up to max. open circuit voltage,
i recommend to add 4 x 10W chip in a warmw. spectrum,
to get some reds into your 4000K led build - for blooming.

Any chip with i.e. Vf = ~12V and can stand 1000mA is fine // 2 in series 2 parallel helps to reach full load of 320W.
Parallel to a 10W chip you then may try, to drive a 12V fan, if he is made to work in a 500mA range.(6W)

You have to fix all on a heatsink able to sink ~240W of heat.

may be you are also interested how to wire chips in a row without wires

View attachment 4090273

Lol like I said parralel scares me. Why would putting a fan in series with the cobs be a bad idea?

I anticpated the heat at driving the selected cob at 1400ma that's why I want to use that extra space to run the fans.

I do have a soldering iron so I might as well get used to soldering and you are right the only way to do this is to try.

Still not comfortable with parralel wiring...I might consider better cobs to pair with the drive I selected so that they run more efficiently

My reasoning is that if I buy a better drive now the hlg 340 then I will be able to save a bit when upgrading the cobs

 

[klx]

Yay!!!

Will this work 12 sq ft area? How many plants could I do with it?

That is not enough light to max out 12sq ft. Get 6 Vero 29Cs instead and run them at 1400mA and add a dimmer if you want, but it will give you the option of fully maxing that space out. You will find that more light does actually = more yield.

 

[Mazoz]

That is not enough light to max out 12sq ft. Get 6 Vero 29Cs instead and run them at 1400mA and add a dimmer if you want, but it will give you the option of fully maxing that space out. You will find that more light does actually = more yield.

Okay bro. Did i mention the grow cab has a 400 HPS/MH as well. Was hoping to combine it with the LED and then have enough light cover for the whole grow cab which will be scrog.

Anyways i went looking for a new chip to match tot he selected driver and i found this:

https://www.digikey.co.za/products/en/optoelectronics/led-lighting-cobs-engines-modules/111?k=976 1467 ND


Much better what do you think? Pair 4 of these with the same Meanwell HLG 320H - C 1400B driver described earlier in the post and i will get an estimated 70.98 watts per a COB for a total watt 283.92.

Is the spectrum right though? Thoughts?

 

[Mazoz]

i wouldn`t mix up leds and fans in a row !!!

may be you are also interested how to wire chips in a row without wires

View attachment 4090273

I only see solder there... is this safe? If it is....goodbye wires....

 

[mahiluana]

Why would putting a fan in series with the cobs be a bad idea?

if you wire a dc motor in series to leds - you will get a pulsed current and flux.
even in parallel you will cause a steady changing Vf.
it works, but is not desired in a constant current circuit.

I like, that you want to fill up your mean well to full power -
and save the money for a fan driver (5$), but imo 24V * 1400mA is also bit too much,
to spent it for fans.

there is another argument not to do it in series...
as you want to get your Vf as close as possible to the max. open circuit voltage
you have to be carefully with dc motors, also because they need a lot of current, when you start them. Cold led chips also have significant higher Vf when you start them in the morning.
Then it can happen, that your driver is not able to pull enough current through your lamp -
and starts blinking (dimming down the driver helps but isn`t 110% as we like)

so if you want to squezze out the max. of power, add some smaller chips (there are i.e.
10W CREE Vf 3,5V * 3,5A )
with those little ones you could reach the max. // step by step adding them to your series.

You still do not reach the recommended 400W / 12sqf with 1 x hlg-320

 

[mahiluana]

I only see solder there... is this safe? If it is....goodbye wires....

it`s a watercooled build - and to bring 125W of led chips this close together is not recommended for pasiv- or aircoolers.



BTW that`s the cheapest, most effective heat sink I know - aluminium sq tubes 8$/m
as i`m harvesting weed&hot water - i can pay 60% of the lamps electricity bill with the savings of my hot water bill.

If you can afford 180$ for a heatexchanger 80L your lamp will be paid after 1 or 2 years,
but a 80L water tank also works fine for a basic set up and can be find for free.

With a relative small investment in a tripled energy efficiency you often are able to have big savings during years.

I plan to save the world with these lamps - as in my future a building is heated by a greenhouse
and renewable electricity.

 

[klx]

Okay bro. Did i mention the grow cab has a 400 HPS/MH as well. Was hoping to combine it with the LED and then have enough light cover for the whole grow cab which will be scrog.

Anyways i went looking for a new chip to match tot he selected driver and i found this:

https://www.digikey.co.za/products/en/optoelectronics/led-lighting-cobs-engines-modules/111?k=976 1467 ND


Much better what do you think? Pair 4 of these with the same Meanwell HLG 320H - C 1400B driver described earlier in the post and i will get an estimated 70.98 watts per a COB for a total watt 283.92.

Is the spectrum right though? Thoughts?

Ah ok in that case then yeah all good. Regards spectrum, I use 4000k for veg and 3000k for flower but honestly I dont think it makes a lot of difference.