Heat from 1200W of 1212's/vero 29's/cxm-22/cxb3590 compared to 2x 600W?

CobKits

Well-Known Member
oh right i forgot about that

i think that cooling the cob proper would be more efficient than trying to harvest heat from the cob which will likely dim it.

also isnt the voltage related to delta T across the peltier? is ambient temp on the cold side enough?
 

BobCajun

Well-Known Member
oh right i forgot about that

i think that cooling the cob proper would be more efficient than trying to harvest heat from the cob which will likely dim it.

also isnt the voltage related to delta T across the peltier? is ambient temp on the cold side enough?
I think so, you need a certain temperature differential, depending on the unit. Harvesting energy from a heat sink is obviously not practical or cost effective. It was just a thought, which I later found to be misguided. Their only real use is for small coolers I guess, meaning like drink coolers, they're called power coolers. For COBs, heat sinks and possibly heat pipes to help, but they're also very costly and probably not even necessary for the wattages commonly used.
 

Raging Stalk

Active Member
No, the easiest way is to have the cob to create as little heat as possible and use a more efficient heat source if additional heat is needed.
 

tikdo

Member
i run 2x 600 watt hps in a 3 meter long room it gets warm but i can keep it around 25c steady with a few fans and intake and outtake fan. with out the fans tho it would b around 30-35c in my room that is
 

goofy81

Well-Known Member
Hi, I can chime in from this from my "real experience".
I previously had 6k of hps to close to 6k of LED (~5800).
Heat is definitely still there but no where near as much. I'd say my room is roughly 6-8c cooler most of the time (room used to hit 40c on the hottest of days and now with LED maybe 32-33c max).
I did have one problem however, my humidity seemed a little bit higher than when I used HPS. Most likely due to hotter air holding more water (it's "relative"humidity afterall).

LED was definitely worth it for me, as that temperature drop was huge to plants.

Anyway, as always. Everyone's room and outdoor climate is different. But living in one of the hottest developed cities in the world. I was very very with LED.

Edit. When I had HPS all my ballast were in a separate room, and even now all my LED drives are in a separate room.
 

mahiluana

Well-Known Member
where it still produces light
if you drive 10 cobs @ 10% of the typ. current, you have ~ the same heat production
than 1 cob @ 100% typ. current. ~ The difference is more light output.
To run a chip @ 10% current can easily double efficiency eg. 100lm / w ---> 200lm / w
To emit the same amount of light you need only 5 cobs @10% to substitute 1 cob @ 100%.
You will spent only half of the power, but still ~70% of this power will be changed into heat.
 

Raging Stalk

Active Member
if you drive 10 cobs @ 10% of the typ. current, you have ~ the same heat production
than 1 cob @ 100% typ. current. ~ The difference is more light output.
To run a chip @ 10% current can easily double efficiency eg. 100lm / w ---> 200lm / w
To emit the same amount of light you need only 5 cobs @10% to substitute 1 cob @ 100%.
You will spent only half of the power, but still ~70% of this power will be changed into heat.

Uh no, that's incorrect.

Your numbers and assumptions are wrong. For example a Vero 29 3000k 80cri goes from 155lm/w at 1710ma (100% nominal) to 258lm/w at 250ma (15% nominal) which is a significant increase in efficiency of 66%. That means all of those 7 cobs produce 66% less heat in total than the nominal run cob using the same amount of watts for either the 7 cobs or the 1 cob.

I immediately knew when Yodaweed liked it. He is always wrong.
 

Raging Stalk

Active Member
maybe off the back but the light they emit will also turn into heat so 100W of either setup in a room will produce the same overall heat

Well the plant will use more of the light energy to create more plant material so it would still be less over all heat even from the light portion.

Splitting hairs here but the point is, more cobs the better.
 

Raging Stalk

Active Member
well same heat, more usable photons

I was going to disagree but I see the point as it is literally the same amount of heat just in a different form. My position was the concern of the heat we need to remove form the cob.

Actually we should be saying energy since they are interchangeable with light and heat.
 

mahiluana

Well-Known Member
He is always wrong.
:peace::bigjoint:I think he`s a good man with an golden instinct - like me.

produce 66% less heat in total
You wanted to say more lumens, but you said less heat - so the winner is...........Yodaweed.

If i do the same calculation for the measured cree2530 - I can run this chip @300mA(162lm/W)
or @1600mA(93,6lm/W) light efficiency rise 73% .

So i measured the heat @300mA and there was a lot. ^
As i use my light as a waterheater i`m pretty and shure to pretend that it is ~3 times as efficient as your light emitter with trad. cooling. :fire:
 

Raging Stalk

Active Member
Nah nah, I see what you are saying and am still not convinced that your efficiency test is correct for some reason. It isn't what I am seeing with my Veros being run low on simple aluminum plate. And yeah, I was thinking about doing the same thing using an aluminum container and water to figure out the efficiency.

Only thing I can think of so far is the transfer resistance between the cob surface and water container not being adequate. Also, there will be even more losses for heat since the water was transferring heat back into the air based on its specific heat capacity. Maybe the calculator isn't correct?

Vero 29c 10.3w is 308lm/w at 163ma 63.3vf according to the Bridgelux product simulator. 3000k 80cri LER has been said to be 322 which would put them at a crazy 95.6% efficiency. So watt for watt, the Veros are far more efficient than the cree2530.

And nothing wrong with recycling the heat. I am just trying to minimize the amount of heat generated which means more of the electricity I use goes to light.
 

CobKits

Well-Known Member
Only thing I can think of so far is the transfer resistance between the cob surface and water container not being adequate.
at low currents the difference between Tc and Tj are reduced (some datasheets have a Tj-c resistance measurement in deg C/W)

vero and citi calculators show only 1-3 deg bump in Tj at 25C Tc and 300 mA
 

Raging Stalk

Active Member
at low currents the difference between Tc and Tj are reduced (some datasheets have a Tj-c resistance measurement in deg C/W)

vero and citi calculators show only 1-3 deg bump in Tj at 25C Tc and 300 mA

He is using a cree chip though. Ceramic vs aluminum base.

Oops, forgot the rest,

Maybe that's part of the special sauce with this gens chips, better thermal transfer. Vero 29c are 0.04c/W resistance. The Tj temps I have been reading are only a few degrees off case temps but I expected as such by properly using as5 and classic cpu overclocking techniques from years gone by.
 
Last edited:
Top