JorgeGonzales
Well-Known Member
He is saying the Tj might be slightly hotter for the Citizen at the same Tc. Cree seems to be the worst of the bunch, but they don't publish specs.So you say the vero is the better COB in this instance?
He is saying the Tj might be slightly hotter for the Citizen at the same Tc. Cree seems to be the worst of the bunch, but they don't publish specs.So you say the vero is the better COB in this instance?
i edit my post to make it clearer....So you say the vero is the better COB in this instance?
That's bridgelux at 1400ma vs the 1080 citizens test with. That's not really comparable. The charts I posted have the lpw at 1050 which is a much better comparison against the 1080ma current given for the citizens.Yeah, the larger Citizen 1818 is a respectable .17 C/W. The fairest comparison is with the stabilized DC performance chart and Citizen spreadsheet set to Tc=85C, which leaves the Tj at 100+:
View attachment 3699846
Spoiler alert, the Citizen still comes out ahead. They have excellent temp/current droop moving up.
Thanks for clearing that up.i edit my post to make it clearer....
Gotcha so it will work better with a pinned heat sink because it runs a bit warmer correct?He is saying the Tj might be slightly hotter for the Citizen at the same Tc. Cree seems to be the worst of the bunch, but they don't publish specs.
I posted that for @guod, since he mentioned thermal resistance. Comparing Tc is the fair way to take that out of the equation.That's bridgelux at 1400ma vs the 1080 citizens test with. That's not really comparable. The charts I posted have the lpw at 1050 which is a much better comparison against the 1080ma current given for the citizens.
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I'm focusing on lpw at current. At 1080ma on 36 volt cobs. The 5000k bridgelux put out more lpw. The 4000k put out 5 less lpw on a version you can't get anymore and the 3000ks put out 10lpw less on the same version. Do you not think the increase in efficiency in the new version bridgelux will make up the 5-10 lpw on the 3k and 4Ks, and increase the gap in the 5k? Bridgeluxs 4000k spectrum has more red than the citizens so the actual spectral output is better on the bridgelux than the citizens (for flowering cannabis) at a 5lpw loss. I would take 5lpw loss at a better spectrum. Adding blue to boost lumen output is nice on paper but not in practice when red is more beneficial than blue for our uses. The new bridgelux should pull even further ahead so this argument will be pointless lol. I wouldn't doubt that the new 54ish volt veros will probably give the 1818s a run for their money with lpw and a better spectrum.I posted that for @guod, since he mentioned thermal resistance. Comparing Tc is the fair way to take that out of the equation.
Which is why you need to go back and focus on Tc=25C on both data sheets
You know, it works as a system. Thermal resistance is measured in C/W in this case, which is how many degrees the temperature goes up per watt of heat dissipated.Gotcha so it will work better with a pinned heat sink because it runs a bit warmer correct?
Ok so then I am confused again wouldn't the vero run cooler if both are cooled the same according to what you just explained?You know, it works as a system. Thermal resistance is measured in C/W in this case, which is how many degrees the temperature goes up per watt of heat dissipated.
The system looks like this:
led-> case -> thermal interface material -> heatsink-> ambient air
So you add up the thermal resistance between all those bits, and the lower the number, the cooler the cob stays. Bridgelux has a very low led -> case thermal resistance, but it's only a fraction of the whole.
Do you have digitized SPD data for Bridgelux? Because you can't eyeball either relative or absolute amounts of color with any degree of accuracy. Just trust me here. You may be right, or not, but it's a minor side issue.I'm focusing on lpw at current. At 1080ma on 36 volt cobs. The 5000k bridgelux put out more lpw. The 4000k put out 5 less lpw on a version you can't get anymore and the 3000ks put out 10lpw less on the same version. Do you not think the increase in efficiency in the new version bridgelux will make up the 5-10 lpw on the 3k and 4Ks, and increase the gap in the 5k? Bridgeluxs 4000k spectrum has more red than the citizens so the actual spectral output is better on the bridgelux than the citizens (for flowering cannabis) at a 5lpw loss. I would take 5lpw loss at a better spectrum. Adding blue to boost lumen output is nice on paper but not in practice when red is more beneficial than blue for our uses. The new bridgelux should pull even further ahead so this argument will be pointless lol. I wouldn't doubt that the new 54ish volt veros will probably give the 1818s a run for their money with lpw and a better spectrum.
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1, were you only talking abound bridgelux in that post because the v22 and bridgelux are one in the same.Do you have digitized SPD data for Bridgelux? Because you can't eyeball either relative or absolute amounts of color with any degree of accuracy. Just trust me here. You may be right, or not, but it's a minor side issue.
OK, I will use your first example. At 5000K, Tc=Tj=25C (which is a borderline dishonest way to rate lm/w on an LED) the V22 makes 5730 lumens, correct?
The Bridgelux makes 6382 lumens, or 170 lm/W. Got it? Good.
It would in theory, yes. But only by .17-.08 C/W in the case of an 1818 vs Vero 29. So .07 C/W, so maybe 2 degrees running 50W at 50% efficiency. As much as .25 or so C/W with the 1212 vs Vero 29. But more efficiency can make up for greater tyermal resistance.Ok so then I am confused again wouldn't the vero run cooler if both are cooled the same according to what you just explained?
So all this back and forth over minutiae at the end of the dayIt would in theory, yes. But only by .17-.08 C/W in the case of an 1818 vs Vero 29. So .07 C/W, so maybe 2 degrees running 50W at 50% efficiency. As much as .25 or so C/W with the 1212 vs Vero 29. But more efficiency can make up for greater tyermal resistance.
It can matter, but we cool for our cobs, not somebody else's, if that makes aense. The Cree PCT paints a pretty bleak picture for thermal resistance, from memory. Almost enough to matter, but they are very efficient so it's a bigger percentage if a smaller percentage of heat watts.
Anyway.
It's worth it if you learned something.So all this back and forth over minutiae at the end of the day
We are talking about the V22 here, and even at Tc=85C, which is as fair to Bridgelux as you can be with it's better thermal resistance, the 1212 poops on it.at 50 Watt the vero29 has a temp-lift of 0.08x50= 4°C
the 1212 at the same watts has temp-lift of 0.34x50=17°C
the Cree cobs stay in the same range as the vero and nichia is like citizen on
thermal resistance
they maybe cheap but you have to pay for better heatsink to get the same junction temp
and by the Way we have only a handful manufactors of phosphors for leds. and they are all cooking the same water at a CRI of below 90.
do you know what makes the cree and vero to have a lower thermal resistance than citizen/nichia?the Cree cobs stay in the same range as the vero and nichia is like citizen on
thermal resistance
.
There is no dog fight. I don't have allegiance to corporations. They aren't sports teams.1, were you only talking abound bridgelux in that post because the v22 and bridgelux are one in the same.
2. Still not a valid point. If stick a 5000k 1212 on a driver that pushed on 1050ma it will put out 155lpw according to their data. If you put a v22 on that same driver at 1050ma it would be putting out 157lpw yeah? So exact same power consumed bridgelux comes out on top with the 5000ks. 5 under with more red in the 4000k and 10 under in the 3000ks with more red in the spectrum.
Have you experimented using both? I have and do run both so at least in practice I know which works better, but I also have the data. Again bridgeluxs new versions come out in the next couple weeks so will see if you still even have a dog in this fight at that point.
I'm not saying citizens are bad, just that bridgeluxs spectrum is a bit better for our needs(flowering) and i woud be very surprised if the efficiency across the board doesn't do a good job of overtaking the citizens with the v22s and possibly even on the vero 18s. The vero 29s should kill the 1212s and we'll see how the my do against the higher voltage 1818s and bridgelux is also doing a 54v version on the 29s.
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