Off Grid 12 Volt DC Ceiling Fans

[Jafo]

So my long quest for an old style wind up ceiling fans has been a bust. I see a lot of diagrams, museum pieces and theory, but no actual product to buy. So I started looking for low power, 12V ceiling fans. What do you all think of this?:

Global Electric 42-inch Non-Brush Ceiling Fan for RV, Rustic Bronze with Wall Control, Black Blades



1amp at 12v (12 watts), looks like it would be a perfect solution. You could run the thing all day on even the smallest battery bank. Does anyone have any experience with these things?

[hierony]

To be honest, I would not trust anything that moves air and rotates but doesn't give some measure of how much air (cfm), and at what speed (rpm); noise levels (measured in decibels, dB) is also likely of interest to you. Assumptions can prove spendy. I would expect this fan at that power to be somewhat weak, moving a little air and fairly quiet--but no guarantees. If you can track down the manufacturer, you might call them to ask about these details. Amazon reviewers some to like it though.

I would suggest little axial fans--much smaller, cheaper ($10-20 each), various voltages/powers/cfm, and actually characterized. Here are two different models that might meet your needs: a 39 dB/61 cfm model, and a 30 dB/2.6 cfm model. A reference for different decibel levels might be handy.

[hierony]

Well this study is interesting--gives you an idea of good/bad ceiling fan use and typical power draws & cfm numbers. Doesn't say anything about noise though. Still, food for thought.

[Jafo]

Well, I just asked the manufacturer what the CFM and RPM specs are. Let's see if they reply. It is the beginning of a holiday weekend, so I wouldn't expect anything until next week, but you never know.

[Jafo]

Well, here is their reply:

"the RPM for this model is :1st speed 168 RPM, 2nd speed 150 RPM, 3rd speed 133 RPM, 4th speed 115 RPM, 5th speed 98 RPM and 6 speed is 85 RPM. The blade pitch is 17 degree. Sorry we don't have DFM testing result. Please let us know if there is anything further we could do to assist you. Thanks & Best Regards,

Global Electric Products, Inc"


So it appears the fastest speed is 168 RPM.


I don't think that sounds all that bad really for a fan that size.

[hierony]

Using some crude numbers based on estimated geometry and those rpms, you should get something like 300 cfm at the slowest and 600 cfm at the fastest. No guarantees, naturally

From perusing ceiling fan specs, 12 watts is not an uncommon power--a number of fans draw that much (or less) at slow speed. Normal cfm for ceiling fans is all over the place: 1000 cfm to 6000 cfm (for the high speed), so 600 cfm is not unreasonable for a tiny 12 watt motor running on 12 Vdc.

I found the previously-linked study interesting because it highlighted good usage patterns for ceiling fans that I did not know about: use it to move air *while* the room is occupied; perceptible air flow is only directly below the blades (so put the fan right above where you want to feel the air); plus some other details.

[MT Rod]

It is interesting, I have been researching this type of fan for about the last 2 weeks. If everything goes as planned I should be visiting a factory in about 10 days.

I thought it might be important to have a fan that is reversible, and has a remote control. Do you think that is important?

I'm also looking at some very interesting 12v LEDs that I plan to bring back to the US this summer. I'll try to start a thread in a few days if anyone is curious/interested.

Rod
rodyurtlocker.com