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Energy Options => Wind Power => Topic started by: Speaker0311 on August 17, 2014, 06:22:05 PM

Title: ?'s on ceiling fan turbine
Post by: Speaker0311 on August 17, 2014, 06:22:05 PM
Has anyone built a turbine from a ceiling fan?

I'm looking to attempt this but I would like to get a few questions answered first.
1. Is it a waste of time?
2. When adding permanent mags does more magnetism=more power generation?
3. Is it better to stack more thinner mags or fewer thicker mags or does it matter?
4. If you have built/tried to build one what problems and or solutions did you come across?
5. Would a small electric motor be a better/worse option, something like off an air compressor?
I'm not looking to power the world with a homemade wind turbine, but I would like to be able to charge a small 12 volt battery bank that would see very limited use. Maybe a small light bulb in my chicken coop or something along those lines.

Thanks guys.
Title: Re: ?'s on ceiling fan turbine
Post by: Comrad on August 18, 2014, 05:10:08 PM
I'm a little curious about this one. When you say a ceiling fan, you literally mean the thing that hangs from your bedroom ceiling, about 4 foot across?

I'd be curious about the strength of the actual unit itself, especially if you're taking something that's meant to hang from a ceiling and using horizontally. Its bearings work on an almost entirely axial load, a horizontal wind turbine usually uses something like a tapered roller bearing, allowing it to deal with both axial and radial loads. Usually you can get away with something a little less suited, since its only a small unit, but I would still question the use of a ceiling fan. Something like a pedestal fan would probably be more appropriate.

To answer your questions, in my opinion:

1: Nothings a waste of time if you feel that what you've done was worth while for either practical results, fun in building something, or serving as a learning experience. But, I doubt it would work real well.

2: More magnetism does lead to more power generation, but, then you're putting greater load on your turbine. In a purely theoretical sense, it doesn't really matter, you'll get the same generation since you'd be spinning faster with less load for the motor to fight against. For a motor with a magnetic field perpendicular to the direction of rotation, the general former for output voltage is emf =  vBL with v being your angular velocity, B being your field strength, and L being your rotor length. You can only create power by inputting an equivalent level of power, this is the conservation of energy principle. As you increase your magnetic field, B, you'll have to fight harder for your magnetized rotor to cross the field, meaning you'll turn slower, still giving you roughly the same amount of power. If this wasn't the case, everyone would just chuck huge magnets on little devices and create a heap of power. The best option is to play around with it a little and check your efficiencies. I'm guessing you're not going to be precision machining this device with special engineered materials, so, you want to keep your rotational velocity pretty low, that way you don't have to worry about over speed on bearings, things flying off, etc... So, put a magnetic field around it that allows consistent generation, without the unit having to spin too fast.

3: For your purposes, it doesn't really matter.

4: I've made wind turbines before, but I've not built one from a ceiling fan, but, what I said in the first paragraph says what problems I'll imagine you'll come across.

5: A ceiling fan is an electric motor. Any electric motor can be a generator, and any generator can be a motor. They its just whether the electricity is applied to create a movement, or a movement is applied to create electricity. The thing to look out for is whether you're using an AC or DC motor. A ceiling fan will almost certainly be AC. You'll need to convert this to DC before you can feed it into your battery bank. You'll also need a charge controller for your batteries to stop them from back flowing into the turbine and turning it into a motor, and to prevent over/undercharging. You can buy units that'll do this for you, or you can make them yourself. To convert AC to DC you'll need a bridge rectifier, which is basically 4 diodes arranged such that a positive signal is always generated, however, it does still vary in amplitude, so you'll need to use some capacitors to level the voltage out to a nice smooth output. Then you'll need to use some filters and whatnot to make sure you're charging your batteries at that oh-so-sweet 13.4 volts that they love so much.

I hate being the kill-joy for people's ideas, but, in my opinion, it's more work than its worth. If you still want to give it a go, by all means, do it, it should be a lot of fun, and I'd be keen to see some photos/video of it in operation. However, for simplicity, you can't go past a solar PV system. They're so much easier. There's no moving parts, and they require almost no maintenance. You'll still need a charge controller, but you need it either way, and if you compare the cost of a PV system versus the cost of trying to modify this fan, its probably going to be cheaper to go the solar route.

Let us know how you end up going with it.
Title: Re: ?'s on ceiling fan turbine
Post by: Skunkeye on August 20, 2014, 11:45:32 PM
I think Comrad is right when he says it's probably not worth the effort.  For one, ceiling fans aren't sealed against weather in any way.  Even most "outdoor" fans are meant to be installed in a protected location, where they won't get rained on.  The blades are flimsy affairs that probably won't stand up to much abuse from shifting winds and may not last long in the weather in any case.

For what it would cost to turn a ceiling fan into a durable turbine that produces useful energy, you'd be close to the cost of a small turbine, anyway.  I've seen turbines rated for a couple hundred watts in the $250 range.  I'd be suspicious of the quality of such a turbine, but could it be any less reliable than a homemade ceiling-fan turbine?   ;)

As a learning exercise, it could certainly be fun, but from a practicality and durability standpoint, you'd probably be better off just building completely from scratch.
Title: Re: ?'s on ceiling fan turbine
Post by: Perfesser on December 18, 2014, 08:01:57 AM
I understand what you're trying to do and why you were thinking the fan but this might be more practical - and tested.
Title: Re: ?'s on ceiling fan turbine
Post by: Speaker0311 on December 22, 2014, 04:01:14 AM
IT'S ALIIIIIIVE.   Well generating voltage anyway I got the magnets installed and did a little reconfiguring on the housing to fit it all and now I'm using silicone to waterproof the whole thing. spinning it by hand (no blades installed yet) I'm getting up to around 20 volts. The plan now is to finish the blades and build a frame to mount it on my barn roof wired somehow into a charger for aa's and the like for the wife's photography uses. I know I need to go through a bridge rectifier to get 12v dc but after that I haven't figured out the next step to get me to charging small batts's.   Also I like the washing machine idea and building a  VAWT might be a later project (I have 3 more fans to play with)  but this is what I have now so this is what we are going with. Cost so far on magnets, silicone, threaded pipe, around $25.
Title: Re: ?'s on ceiling fan turbine
Post by: trekker111 on December 22, 2014, 07:15:11 AM
Pics? Directions?

Title: Re: ?'s on ceiling fan turbine
Post by: Speaker0311 on December 23, 2014, 06:07:40 AM
sorry didn't take pics, but if you go to youtube and search for how to ceiling fan wind turbine you will find several good video series on how to make them work. muddymuddymudman makes a very in depth(allmost too much) series on how to do it.
There seem to be a few variations but the general idea is the same. I got a youtube downloader and got a few of them, watched all of them several times then adjusted their plans to fit my fan.

The only helpfull things I didn't find there: Use SHOEGOO instead of epoxy (this is also the USMC's secret weapon and can be found in the shoe dept of walmart), and I recommend buying the small 1/16th thick neodymium magnets 100 for about $10. They will allow you to get magnets very close to the stator and can make more than enough force to stop the blades from spinning if you use too many. Which means you can play with amount to get it right for your turbine. 
Title: Re: ?'s on ceiling fan turbine
Post by: Bad_apple on August 06, 2016, 10:31:41 PM
This project has been on my list for a while. Might just be time to get on it. I have also seen this done with treadmill motors as well as washing machine motors. Nice to se a fellow marine!