Most efficient 12V DC fans?

Mariner777
Mariner777 Solar Expert Posts: 29
Currently have a pair of fantastic vent endless breeze 12V DC only 10 blade fans. They draw from 1-3 amps I think depending on speed. They are great and far better than the little 3 blade car fans I used to have that can barely move any air. Anyone know of more efficient ones? I find they are my most prized possession in these latitudes and would be dying without them... A 300 watt mini split would be awesome but unrealistic dont have the power for that so fans it is...

Comments

  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Most efficient 12V DC fans?

    Those fans are about the best you can get, there is little you can do to reduce the amperage of a fan w/o also dropping air flow.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • DavidOH
    DavidOH Solar Expert Posts: 112 ✭✭✭
    Re: Most efficient 12V DC fans?

    Have you looked at computer fans?

    http://www.mwave.com/mwave/SKUSearch.asp?scriteria=AA76746

    250 mm is about 10 inches.
    This produces 105 CFM while making less than 25 dB.

    You can get speed controllers to vary the output.
  • MiamiSunrise
    MiamiSunrise Registered Users Posts: 22
    Re: Most efficient 12V DC fans?

    I second the recommendation of 250mm computer case fans. They run very slow, almost like a ceiling fan, and move a good amount of air with barely noticeable noise.

    The Vari-Cyclone DC ceiling fans are also pretty good. My only complaint on them is that they have a brush motor, which will (but only after many years of operation) wear down its brushes. They are one of the few fans that is still available with the "Gossamer Wind" curved blade design instead of just flat paddles. The brush motor is good to go from just a couple volts up to 24, and a DC PWM speed control can be used to dial it back.

    If you come across any Rotron Caravel DC fans available from an electronics surplus house, pounce on those. They are NOT QUIET when run full speed... but full speed, they are unloading 550 CFM in your face! Definitely use a 48v fan on 12 or 24, or use a PWM speed control to slow these down, unless you just need serious blowage. The Mixtus series are also really powerful and can be throttled back to be a more pleasant indoor fan, but I've never seen these show up surplus yet - they're probably a very limited production item due to lack of demand (where on earth do you need a 7.9" 550CFM (free air) tubeaxial screamer that can buck 2.7 inches water column of pressure at 96 watts of power?!)
  • rgs03833
    rgs03833 Registered Users Posts: 16
    Re: Most efficient 12V DC fans?

    Hi,

    I use these O2 Cool 10" 12V DC Indoor/Outdoor Fan with Hook. Works really good and the price is awesome! I took it apart and hooked wire in them because it was AC/Portable, but you can use 12V cause it takes 8 D Batteries.

    They have other ones too which is also good and cheap :)

    http://www.campmor.com/o2-cool-10-inch-smart-power-rechargeable-ac-dc-fan.shtml?source=CI&ci_sku=47189&ci_gpa=pla&ci_kw={keyword}
  • Shadowcatcher
    Shadowcatcher Solar Expert Posts: 228 ✭✭✭
    Re: Most efficient 12V DC fans?

    I use two 120 mm Antec case fans in out teardrop trailer, published specs put them at 100cfm each on high.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: Most efficient 12V DC fans?
    rgs03833 wrote: »
    Hi, I use these O2 Cool 10" 12V DC Indoor/Outdoor Fan with Hook. Works really good and the price is awesome! I took it apart and hooked wire in them because it was AC/Portable, but you can use 12V cause it takes 8 D Batteries.}

    I'll second the O2cool fans vote they really move the air and run about 13 watts through a wall wart so likely about 1 amp at 12 volts. Wall wart is 12 volts, I though .8 Amps but don't have one with me, I own 5 and have had only one die after 4 years of service. before I had AC(air conditioning) it's all I used.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Most efficient 12V DC fans?

    I used a Wal-Mart camping fan as an attic fan. It DOES work well, but it produces a fair amount of RF noise. Particularly in the 300-400MHz range, same as my garage door opener transmitter/receiver. Consequently, the opener quit working via the remote. Took a while to figure this one out.

    chinafan1.jpg

    This fan draws a little under 450mA at 12V. I connected it directly to a 15W solar panel. No regulator, no sensor. Sun up, fan runs. Sun down, fan off. Simple!

    dscn5310-1.jpg

    This fan uses a brushed contact type motor. In the R/C world, we simply add some capacitors to keep the spark noise to a minimum. I tried that, no improvement.

    img_1455.jpg

    Ultimately scrapped this fan for this application. I will now only use brushless fans because of the RF issue.

    A couple of computer muffin fans attached to a piece of hobby crafting foam board, and no RF noise.

    dscn6212.jpg

    dscn6214.jpg

    I bought these a while back at an electronics surplus website for a few bucks each. They work well, but can be a bit noisey to the ear if you're near them. The fans get in/out of sync, changing the hum to a bit of an oscillation. Since this was in the garage, not an issue.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Most efficient 12V DC fans?

    2mt,
    sounds like you listen in on that range of frequencies, but i find it difficult to believe it is necessarily stronger there than in many other areas lower in the spectrum as it probably just seems that way to you because that is the area you like to hear. in any case interference is interference. how did the brushless fair as to noise for you and is the air movement sufficient?
  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Most efficient 12V DC fans?

    Be wary of the cheap surplus computer fans. I used a half-dozen of them around my house to move my wood stove heat, so they were going 24/7 5 months of the year. I had to replace the cheapest ones after a year, some others lasted 2 years. The problem is the bearings wear - you trade lack of brushes for something else.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Most efficient 12V DC fans?
    techntrek wrote: »
    Be wary of the cheap surplus computer fans. I used a half-dozen of them around my house to move my wood stove heat, so they were going 24/7 5 months of the year. I had to replace the cheapest ones after a year, some others lasted 2 years. The problem is the bearings wear - you trade lack of brushes for something else.

    The difference between bushings and ball bearing units. Buy the better ones
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Most efficient 12V DC fans?

    The nice thing about computer fans is that they can be had nearly free. I go to my local electronic recycler, and buy them of $.25 each. Even if they fail ( which I have never had one fail) it is no big deal. My only complaint is they do make some noise, but I now often run 24 vdc fans on 12 vdc, much quieter, but still moves a bunch of air, depending on application.

    T
  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Most efficient 12V DC fans?
    niel wrote: »
    2mt,
    sounds like you listen in on that range of frequencies, but i find it difficult to believe it is necessarily stronger there than in many other areas lower in the spectrum as it probably just seems that way to you because that is the area you like to hear. in any case interference is interference. how did the brushless fair as to noise for you and is the air movement sufficient?

    Hi Niel,

    In my shop at work, I have a spectrum analyzer I used to determine the frequency of my garage door opener transmitter. This is the 300-400 MHz range I was referring to. When I powered up the fan in the shop, that part of the spectrum was trashed with RF noise from the brushed fan. Got a pic somewhere. It probably trashes a wide range of frequencies, but noise in this part of the spectrum prevented the low power garage door opener transmitter to be heard by the receiver. So couldn't use the remote unless I was practically standing under the receiver itself. My goal wasn't to find out how bad the fan was, but rather why the opener wouldn't respond to the transmitter.

    The audible noise from the dual muffin (computer) fans can be heard at minute 1:30 on this video, also the hum of cicadas outside:

    http://www.youtube.com/watch?v=FMdDlZaZ8Gg

    While they do produce an audio noise from the fans slicing the air, they produce very little RF noise since they are brushless - no spark gap RF noise.

    The bigger issue is the smaller fans don't move as much air as the larger fan, obviously. So the fix is to use more fans. The more that are used, the louder the audio signature. I had planned on using 4 fans, but 2 were loud enough at this location. They could be heard in the kitchen, even with the garage door closed. Adding more would have made the issue worse. My next plan was to relocate these from the attic access door to the gable end vent. But I've since sold this house recently, and the new house does not have a gable end vent. It's mostly a hip roof, so have to start a new plan to cool the attic.

    Hope this clarifies my previous post.
  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Most efficient 12V DC fans?
    techntrek wrote: »
    Be wary of the cheap surplus computer fans. I used a half-dozen of them around my house to move my wood stove heat, so they were going 24/7 5 months of the year. I had to replace the cheapest ones after a year, some others lasted 2 years. The problem is the bearings wear - you trade lack of brushes for something else.

    They also need periodic lubrication. Peel the label back on the center of the fan, put in a couple of drops of oil (I use Tri-Flow), stick the label back down.

    Even a cheap fan can run for many years with a little PM.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Most efficient 12V DC fans?

    ok i fully understand now. those fans are a bit noisy. you could slow them down to reduce the noise by lowering the voltage some and then maybe add a few more to keep the same or more quantity of air moving.
  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Most efficient 12V DC fans?
    2manytoyz wrote: »
    They also need periodic lubrication. Peel the label back on the center of the fan, put in a couple of drops of oil (I use Tri-Flow), stick the label back down.

    Even a cheap fan can run for many years with a little PM.

    Yup, even after doing that they wouldn't last very long. But that did help for a while. No big issue for me anymore, I installed a whole-house ventillation system which made the little biscuit fans obsolete.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: Most efficient 12V DC fans?

    I am getting ready to replace my whole house ventilation fan (currently using a 120 mm radio shack computer fan which draws about 5 watts). My fan is 4 years old, runs 24/7, and its bearings are getting noisy. It runs on 12 v DC (via a 120 v AC wall wart). My replacement fan will hopefully be a 24 v fan so that it can run directly from my batteries.

    Has anyone tried a fan with ceramic sleeve bearings? They claim to be very quiet and long lasting. A google search for 'ceramic bearings fans' turns up several manufacturers.

    tia, vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Most efficient 12V DC fans?

    The fans that make the least noise by a long way are ones that use magnetic levitation.. 12v versions only cost slightly more than ones with sleeve or ball bearings. and for obvious reasons never get noisy even after years of use ,and have the added advantage can easily be taken apart for dust removal..