Controlling lots of DC fans (active cooling)

DrBlaze

DrBlaze

Well-Known Member
So I've got 90 1212's so far and once I've completed all my fixtures that will obviously mean 90 small fans running. I was going to buy a Meanwell 12v power supply for them, but the general purpose ones aren't that efficient or adjustable.

Anyone know of a 12v supply that will allow me to "dim" down a bit (9v-12v or even better 6v-12v)?

I'm going to experiment to find the lowest voltage I can use without droop on the cobs.
 
N

Nutria

Well-Known Member
You want a 12v driver for your 12v fans and you want to control fans speed by varying the voltage?
Shouldn't be a good idea to dim through voltage control, you should use PWM dimming as you do with leds
 
Airwalker16

Airwalker16

Well-Known Member
I'm REALLY surprised you'd choose ACTIVE fan cooling over PASSIVE pin fin heatsinks that don't need a fan at all. That's so many fans to keep track of and places for a malfunction. What kind of heatsinks are you using? Some CPU type?
 
G

goofy81

Well-Known Member
Just do what I do and use a ceiling fan.
4x 20-30w ceiling fans to cool 100+
DC ceiling fans can use as little as 5-10watts

But too to answer your question, I thought about this . There are these tiny fan controller chips on eBay I think , in the end it might be more hassle than it's worth.
Ebay " temperature control speed controller alarm module"

Lots of small dc fans will use quite a lot of power! There'll be messy wiring especially with the sensors. These would really make sense to the guys who just grow with a lot less cobs
You might be better off getting a few long throw vortex fans for the job!
 
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DrBlaze

DrBlaze

Well-Known Member
Got 30 Cooler Master 92mm a while back for super cheap. And about to order a bunch more of these: https://www.alibaba.com/product-detail/portable-laptop-cooler-master-775-cpu_60583509720.html?spm=a2700.7724838.2017115.360.46155250c76oXT

The key is finding them with a square area to mount the cob to, so that there's room to tap. It comes down to price really. I can get these shipped for a third of what pin fins will cost me. That really adds up when you've got a lot of area to cover. Plus you then would need lots of fans running to cool the pin fins. With active cooling you don't really need any other fans in the room, I also turn the fans around so they all pull air up through the fixture. Unless you've got a hurricane going on in your grow room, these actives will keep the cobs cooler than pin fins as well, so I get some free photons allong with the extra thousands saved.
 
DrBlaze

DrBlaze

Well-Known Member
friedguy said:
https://www.amazon.com/eTopxizu-Universal-Regulated-Switching-Computer/dp/B00D7CWSCG/ref=sr_1_4?ie=UTF8&qid=1530223639&sr=8-4&keywords=12v+power+supply&dpID=41jyorZ9%2BQL&preST=_SY300_QL70_&dpSrc=srch

and/or

https://www.amazon.com/Converter-1-25-36V-Step-down-Regulator-Voltage/dp/B074XRYC1M/ref=sr_1_2_sspa?s=electronics&ie=UTF8&qid=1530223764&sr=1-2-spons&keywords=buck+converter&psc=1&smid=A2TKGQERXRZT6A
Click to expand...
Umm thanks but... that's a low efficiency power supply (74%). As far as the buck converter goes, maybe, although this one only handles 5A.
 
Airwalker16

Airwalker16

Well-Known Member
DrBlaze said:
Got 30 Cooler Master 92mm a while back for super cheap. And about to order a bunch more of these: https://www.alibaba.com/product-detail/portable-laptop-cooler-master-775-cpu_60583509720.html?spm=a2700.7724838.2017115.360.46155250c76oXT

The key is finding them with a square area to mount the cob to, so that there's room to tap. It comes down to price really. I can get these shipped for a third of what pin fins will cost me. That really adds up when you've got a lot of area to cover. Plus you then would need lots of fans running to cool the pin fins. With active cooling you don't really need any other fans in the room, I also turn the fans around so they all pull air up through the fixture. Unless you've got a hurricane going on in your grow room, these actives will keep the cobs cooler than pin fins as well, so I get some free photons allong with the extra thousands saved.
Click to expand...
How many watts per citi you running?
 
friedguy

friedguy

Well-Known Member
DrBlaze said:
Umm thanks but... that's a low efficiency power supply (74%). As far as the buck converter goes, maybe, although this one only handles 5A.
Click to expand...
Just giving you an idea. There are obviously more efficient PSUs and buck converters that can handle more amperage.
 
DrBlaze

DrBlaze

Well-Known Member
Airwalker16 said:
How many watts per citi you running?
Click to expand...
Did my first couple fixtures at 40w ea, but now thinking of going down to 30w. I build the fixtures around the ELG-240-36a, which I get for about 1/2 the cost of the HLG's. So 6 cobs run at about 40w, 8 run at about 30w (1 driver per fixture). These are just about the last of Bobby's gen5's.
friedguy said:
Just giving you an idea. There are obviously more efficient PSUs and buck converters that can handle more amperage.
Click to expand...
Yes :) I didn't mean to sound like I was dismissing your suggestion. I hadn't considered buck converters, but they may be a good option.

It might come down to PWM vs buck converter if I can't find a good all-in-one solution. I'm not quite sure what the advantages/disadvantages of either would be (having no experience with either ... and admittadly still a bit high on mushrooms atm)
 
nfhiggs

nfhiggs

Well-Known Member
DrBlaze said:
So I've got 90 1212's so far and once I've completed all my fixtures that will obviously mean 90 small fans running. I was going to buy a Meanwell 12v power supply for them, but the general purpose ones aren't that efficient or adjustable.

Anyone know of a 12v supply that will allow me to "dim" down a bit (9v-12v or even better 6v-12v)?

I'm going to experiment to find the lowest voltage I can use without droop on the cobs.
Click to expand...
The Meanwell LRS power supplies are 89% efficient and they are adjustable from 10.2-13.8 volts..
 
Airwalker16

Airwalker16

Well-Known Member
DrBlaze said:
Did my first couple fixtures at 40w ea, but now thinking of going down to 30w. I build the fixtures around the ELG-240-36a, which I get for about 1/2 the cost of the HLG's. So 6 cobs run at about 40w, 8 run at about 30w (1 driver per fixture). These are just about the last of Bobby's gen5's.

Yes :) I didn't mean to sound like I was dismissing your suggestion. I hadn't considered buck converters, but they may be a good option.

It might come down to PWM vs buck converter if I can't find a good all-in-one solution. I'm not quite sure what the advantages/disadvantages of either would be (having no experience with either ... and admittadly still a bit high on mushrooms atm)
Click to expand...
If you're running a measly 30 watts, you could buy small 110mm 40mm height pin fin sinks for the same as the actives.
 
nfhiggs

nfhiggs

Well-Known Member
Airwalker16 said:
If you're running a measly 30 watts, you could buy small 110mm 40mm height pin fin sinks for the same as the actives.
Click to expand...
Not likely. Pin fin sinks are 15-20 bucks apiece - I can buy CPU coolers all day long for under 5 bucks. I got a box of ten last year for $27.90
 
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