DIY COB LED Calculator

bggrass · Nov 16, 2015

I'm a long time lurker here, not many posts, but I've learned a lot from the community. So I created a calculator to make it easier for users to look up different configurations.. Big credit given to SupraSPL for starting all this, and his spreadsheets, that I used for the actual numbers in the calculator. I have attached a screenshot. The actual calculator is in a dropbox as RIU does not recognize the file when I try to attach it to this thread.

I added a few cobs to it, I think currently the most used ones, but if someone wants different cobs as a selection, just post the spreadsheets here and I'll add when I get a chance. The prices are current as of today, but if they change, just post here and I'll update. If you guys come up with a need for a calculation in the calculator, post your suggestions, as long as I can implement it, I'll add the additional box for it.

https://www.dropbox.com/s/gla2g2d5apbf3dt/DIY COB LED Calculator.jar?dl=0

WwW1962 · Nov 16, 2015

excellent smithers..here's some math for ya 36 10w XML's 3.5-3.7 v 1-3mA
might have to split them into 2 drivers..thank you lets see if it works

bggrass · Nov 16, 2015

WwW1962 said:
excellent smithers..here's some math for ya 36 10w XML's 3.5-3.7 v 1-3mA
might have to split them into 2 drivers..thank you lets see if it works

LOL! Hi Witch.

WwW1962 · Nov 16, 2015

Hey Buddy

i got a thread here WWW's DIY LED's and experiments take a look its only 2 pages

WwW1962 · Nov 16, 2015

my math came to 126 volts needed @ 3.5 volts each, minimum , whattya think ?

bggrass · Nov 16, 2015

WwW1962 said:
my math came to 126 volts needed @ 3.5 volts each, minimum , whattya think ?

Seems right. How many amps you gonna run them on?

Edit: you'll only get those 10watts a piece if you run them at closer to 3amps, but might not be the best idea. RS has a thread on mono chips here. You might wanna ask there. I don't know much about the monos

WwW1962 · Nov 16, 2015

bggrass said:
Seems right. How many amps you gonna run them on?

Edit: you'll only get those 10watts a piece if you run them at closer to 3amps, but might not be the best idea. RS has a thread on mono chips here. You might wanna ask there. I don't know much about the monos

45% @ least so 360watts of light watts max about 150-180w would that be right ? im guessing
dimmable driver so i dont cook them all on ignition LOL

bggrass · Nov 17, 2015

There was a little bug with the prices that I noticed today. It has been fixed. Same link for the updated one.

klx · Nov 18, 2015

This is awesome, thanks!

Not sure if it's possible but something that would definitely help out designing a light would be some form of PPFD calculations at different footprints. For example if you could choose 2x2, 3x3...as a footprint and the spreadsheet would calculate the PPFD for the selected configuration.

bggrass · Nov 18, 2015

klx said:
This is awesome, thanks!

Not sure if it's possible but something that would definitely help out designing a light would be some form of PPFD calculations at different footprints. For example if you could choose 2x2, 3x3...as a footprint and the spreadsheet would calculate the PPFD for the selected configuration.

I can add a total PPFD box, and a PPFD per sq/ft, based on user square footage input, and cob configuration selection. Only I need to make sure I'm using the right values for umol/s/W for each cob. I found a chart that I'm looking at, hopefully it is not outdated. I looked into Alesh's excel sheet and SPDs but haven't got the time to think it through. So I have:

Cree cx 3000K 80CRI = 4.66umol/s/W, only the cxb3590CD in the calculator is 3500K and I'm not sure how that changes.
Vero 4000K V2.0 = 4.62umol/s/W

If someone can confirm those numbers, I'll add it.

SupraSPL · Nov 19, 2015

The 3500K probably has a slightly lower QER than the 3000K but I have no idea how much lower so I have just been going with 4.65. I tried to get the 3500K SPD from Cree so we could estimate the LER and QE but so far they have produced it. I think Johnson Grow Lights will have some data on that soon because one of their lamps should be getting tested in an integrating sphere soon.

bggrass · Nov 19, 2015

SupraSPL said:
The 3500K probably has a slightly lower QER than the 3000K but I have no idea how much lower so I have just been going with 4.65. I tried to get the 3500K SPD from Cree so we could estimate the LER and QE but so far they have produced it. I think Johnson Grow Lights will have some data on that soon because one of their lamps should be getting tested in an integrating sphere soon.

View attachment 3546399

Thanks Supra.I'll go ahead and add the current values in, if anything changes later, it will be an easy fix.

bggrass · Nov 19, 2015

SupraSPL said:
The 3500K probably has a slightly lower QER than the 3000K but I have no idea how much lower so I have just been going with 4.65. I tried to get the 3500K SPD from Cree so we could estimate the LER and QE but so far they have produced it. I think Johnson Grow Lights will have some data on that soon because one of their lamps should be getting tested in an integrating sphere soon.

View attachment 3546399

Supra, just to verify my math, so the numbers come out correct, I haven't done the PPFD numbers yet:

totalWatts x efficiency = PARwatts,

PARwatts x umol/s/W = totalPPFD,

totalPPFD / squareFootage = PPFD per sq. ft

alesh · Nov 19, 2015

bggrass said:
Supra, just to verify my math, so the numbers come out correct, I haven't done the PPFD numbers yet:

totalWatts x efficiency = PARwatts,

PARwatts x umol/s/W = totalPPFD,

totalPPFD / squareFootage = PPFD per sq. ft

That D in 'PPFD' means density. Doesn't make much sense to divide density by area.

bggrass · Nov 20, 2015

alesh said:
That D in 'PPFD' means density. Doesn't make much sense to divide density by area.

Ok. How do we calculate it then alesh?

EDIT: Should I just do, totalPPFD box and a PPFD per cob box and leave the area calculation out? Would that make more sense?

Shredderthirty · Nov 20, 2015

so can you run 4 CXB3590 36v ANNNND 4 Vero 29 in series on a hlg-185h-c700??

alesh · Nov 20, 2015

bggrass said:
Ok. How do we calculate it then alesh?

EDIT: Should I just do, totalPPFD box and a PPFD per cob box and leave the area calculation out? Would that make more sense?

Nah I was just pointing that you've got the terms mixed up.
PPF - photosynthetic photon flux - total photon output in a range (400-700nm or 380-780nm)
PPFD - photosynthetic photon flux density - total photon output in a range (400-700nm or 380-780nm) per area
So you can convert lumens to watts, then watts to moles of photons per second and that could be converted to average density.

But no wonder that people are confused even mfgs can't get it right - just found this gem.

bggrass · Nov 20, 2015

Shredderthirty said:
so can you run 4 CXB3590 36v ANNNND 4 Vero 29 in series on a hlg-185h-c700??

Based on voltage forward, all 8 cobs seem to fit on that one. Not sure if there are other factors that play though.

Shredderthirty · Nov 20, 2015

bggrass said:
Based on voltage forward, all 8 cobs seem to fit on that one. Not sure if there are other factors that play though.

yeah that's what i was thinking... anybody else think i just had some "less than perfect" connections to make this problem?

bggrass · Nov 20, 2015

I didn't recognize you initially shred. Your moniker is a little different than the GC one.

DIY COB LED Calculator

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