bassman999
Well-Known Member
As CobKits pointed out 700ma is only 23 watts, so 4 would be 92 watts.
I wouldnt run less than 200 watts in that space personally.
COB efficiency Spreadsheets
- Thread starter nogod_
- Start date
I wouldnt run less than 200 watts in that space personally.
CobKits
Well-Known Member
i made a graph (i like graphs) 
the following is the relative efficiency increase from a given starting current if you double the number of chips and cut the current to each in half
this was with citi 1212
i did some ultra-low current measurements lately with some multiple chip designs to get the low current data. it seems to fit with the other tests but as always take it for what its worth. overall it looks pretty linear to me.
so starting at 3.2A if you double the number of chips and run them at 1.6A you will gain a whopping 26% in efficiency
but say youre at 1.6A and do the same, you gain a little over 15%
once youre at 0.8A, if you try to double you only gain about 9%
obviously the law of diminishing returns is in effect, and the steps are cumulative
from 3.2 to 0.8A is 1.26*1.15=1.45 (+45% efficiency@ 4X the chips)
from 3.2 to 0.4A is 1.26*1.15*1.09=1.58 (+58% efficiency@ 8X the chips)
its all relative..... so taking 30% to 30*1.45= 51% (in other words not adding 45% to 30% to get 75%)
you save on heat abatement as efficiency goes up as well.
now you see why 700-1750 mA is popular
the following is the relative efficiency increase from a given starting current if you double the number of chips and cut the current to each in half
this was with citi 1212
i did some ultra-low current measurements lately with some multiple chip designs to get the low current data. it seems to fit with the other tests but as always take it for what its worth. overall it looks pretty linear to me.
so starting at 3.2A if you double the number of chips and run them at 1.6A you will gain a whopping 26% in efficiency
but say youre at 1.6A and do the same, you gain a little over 15%
once youre at 0.8A, if you try to double you only gain about 9%
obviously the law of diminishing returns is in effect, and the steps are cumulative
from 3.2 to 0.8A is 1.26*1.15=1.45 (+45% efficiency@ 4X the chips)
from 3.2 to 0.4A is 1.26*1.15*1.09=1.58 (+58% efficiency@ 8X the chips)
its all relative..... so taking 30% to 30*1.45= 51% (in other words not adding 45% to 30% to get 75%)
you save on heat abatement as efficiency goes up as well.
now you see why 700-1750 mA is popular
alesh
Well-Known Member
Just keep in mind that these 'real world' tests are just central beam measurements. There is a reason why people don't compare LEDs by their central beams intensity.
As a non native speaker I've always had trouble with this, but shouldn't it be efficacy instead of efficiency when dealing with PPFD/W ?
percentage x percentage point
always hard to explain something when the two are involved
As a non native speaker I've always had trouble with this, but shouldn't it be efficacy instead of efficiency when dealing with PPFD/W ?
percentage x percentage point
always hard to explain something when the two are involved
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Sounds like I need to run them at 1400ma or buy 8 then correct? Same driver I would be using then? Anything else speculated to come out soon? Now that these citizens are so cheap, contemplating doing a grow very soon instead of waiting for spring.
And also, how much brighter would 4-8 1212's at 700ma-1400ma be than my MARS300? My first grow wasn't great, I think because the plant ended up too big for the light. Hoping this will be a big improvement over that junk.
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ttystikk
Well-Known Member
Lol @'non native speaker'Just keep in mind that these 'real world' tests are just central beam measurements. There is a reason why people don't compare LEDs by their central beams intensity.
As a non native speaker I've always had trouble with this, but shouldn't it be efficacy instead of efficiency when dealing with PPFD/W ?
percentage x percentage point
Your command of English is better than most native speakers I've run across!
ttystikk
Well-Known Member
You just gave a big range; 8 chips at 1400mA is going to produce nearly four time the light as 4 chips @ 700mA.
@CobKits I'm having a lil trouble fully grasping what that graph is telling me; using this example, is it saying that using 8 chips @700mA is almost 15% more efficient than using 4 @1400mA?
I meant to say 4 @ 1400ma OR 8 @ 700ma 1212's would be about equivalent, how much brighter would either of these setups be than my MARS300?
MeGaKiLlErMaN
Well-Known Member
So what's it really looking like around 100-500mA? That's the question I'm personally looking for. Might make a flowering light based around that in the future.i made a graph (i like graphs)
the following is the relative efficiency increase from a given starting current if you double the number of chips and cut the current to each in half
View attachment 3798079
this was with citi 1212
i did some ultra-low current measurements lately with some multiple chip designs to get the low current data. it seems to fit with the other tests but as always take it for what its worth. overall it looks pretty linear to me.
so starting at 3.2A if you double the number of chips and run them at 1.6A you will gain a whopping 26% in efficiency
but say youre at 1.6A and do the same, you gain a little over 15%
once youre at 0.8A, if you try to double you only gain about 9%
obviously the law of diminishing returns is in effect, and the steps are cumulative
from 3.2 to 0.8A is 1.26*1.15=1.45 (+45% efficiency@ 4X the chips)
from 3.2 to 0.4A is 1.26*1.15*1.09=1.58 (+58% efficiency@ 8X the chips)
its all relative..... so taking 30% to 30*1.45= 51% (in other words not adding 45% to 30% to get 75%)
you save on heat abatement as efficiency goes up as well.
now you see why 700-1750 mA is popular
wietefras
Well-Known Member
How do you measure double or five COBs then? That would create an offset the COBs I would assume. Guess you could estimate the error by comparing a double COB measurement with a calculated doubling of a single COB.
True, but still. Especially in situations where you might expect issues due to different beam angles or offsets it's reason to be extra careful with interpretations.
Even with a sphere the comparisons could still be "incorrect" though. Cree COBs get binned for efficiency and those bins can be 10% "wide". So when comparing two COBs you could have perfect sphere measurements and still measure almost 20% difference or 0% difference were on average a 10% difference would be "typical".
CobKits
Well-Known Member
i know nothing aobut that fixture and how bright it is, its not even a remotely similar spectrum so not sure how apples to apples we can compare
CobKits
Well-Known Member
minimal gains below 500 mA it seems. hard to tell without a sphere or an array with measurements
bassman999
Well-Known Member
Im not the authority here, but I run low current but make up for it with multiple sources of light, and keep canopy relatively even and dont let plants get tall.
I dont want larf at the bottoms and have done well so far
Without checking. I thing you could run (12) of the citi 1212 cobs off a single hlg-320-700 or ( 8 )cobs off of the hlg-320-1050
Bigdaddy212
Well-Known Member
Can someone post a link to the chart of how many driver can power the cobs I'm having a hard time finding it and have been looking for awhile
bassman999
Well-Known Member
Bigdaddy212
Well-Known Member
Thanks Bassman that's the one but there is an updated one with the 240's on there I'm hooked on the 240-1750
Bigdaddy212
Well-Known Member
Thanks CobKits that is the one I was looking for now for the next dumb question how do you determine wattage use per driver per cob I've got 24 cobs on 4 240 1750 and 2 185 1400 going all 1750's and taking the 1400 to 6 cxa3590. Hate to ask again but how is that configured
CobKits
Well-Known Member
go to cree pct:
you'll see that at 1750 each cxb is 35.5 V. 4 of these would be 142V
the HLG-240H-C1750B is 143V. so it can handle it
im unclear what youre saying
presumably the 4 HLG-240H-C1750B already have 4 CXBs on them and then you have 2 more HLG-185H-C1400B with 4 cobs each, and you are upgrading these last 2 to HLG-240H-C1750B to run them a little hotter.
as for the HLG-185H-C1400B you can run 3 cxbs per driver at 1400mA ea, or 4 cxbs per driver at 1400ma ea. you cant run 2 because the cob voltage is too low for the driver. you cant run 5 because the driver doesnt provide enough voltage to run 5 cobs
hope that helps. another option is to throw some higher voltage cobs on the 1400s. 50V cobs at 1400mA are about the same power (62-68W) as the rest of the cxbs you are running at 1750. so all your cobs would be somewhat equally intense which might be a little easier to manage
1818s are pretty cheap for this, the new veros in 50V are also a good option if the color you want is out yet
you'll see that at 1750 each cxb is 35.5 V. 4 of these would be 142V
the HLG-240H-C1750B is 143V. so it can handle it
im unclear what youre saying
presumably the 4 HLG-240H-C1750B already have 4 CXBs on them and then you have 2 more HLG-185H-C1400B with 4 cobs each, and you are upgrading these last 2 to HLG-240H-C1750B to run them a little hotter.
as for the HLG-185H-C1400B you can run 3 cxbs per driver at 1400mA ea, or 4 cxbs per driver at 1400ma ea. you cant run 2 because the cob voltage is too low for the driver. you cant run 5 because the driver doesnt provide enough voltage to run 5 cobs
hope that helps. another option is to throw some higher voltage cobs on the 1400s. 50V cobs at 1400mA are about the same power (62-68W) as the rest of the cxbs you are running at 1750. so all your cobs would be somewhat equally intense which might be a little easier to manage
1818s are pretty cheap for this, the new veros in 50V are also a good option if the color you want is out yet
Bigdaddy212
Well-Known Member
presumably the 4 HLG-240H-C1750B already have 4 CXBs on them and then you have 2 more HLG-185H-C1400B with 4 cobs each, and you are upgrading these last 2 to HLG-240H-C1750B to run them a little hotter.
That is correct and then take the two 1400 to an additional 6 cxa's cause I have to do something with these and run another setup mostly 6 cobs on a rail to 12 girls
That is correct and then take the two 1400 to an additional 6 cxa's cause I have to do something with these and run another setup mostly 6 cobs on a rail to 12 girls