# Project: Charging devices with Eolic Energy

#### Elboxd

Joined Oct 19, 2015
15
Good evening, everybody, I'm new here so if I made any mistake, I apologize in advance.

I've been thinking in a project from a while now and I want to share it with you seeking for your help and wisdom.

Basically, I want to build a small wind turbine in order to charge a smartphone or a tablet and so far I have the following:

1. I found a rather big computer fan and these are its specifications:

Name: Yate Loon D14BH-12
More: 2-pin, 12V, 0.7A @ 2800RPM, 140CFM, 48.5dBA

Here is a photo:

So my question is:

- If this fan needs 12V in order to work and it's RPM is 2800, could I use it the other way around? I mean, Use the wind in order to create energy.

Note: I made a small test connecting a small LED and I made the fan spin and it turned on a little bit for a little while (about 2-3 seconds) and it's obviously because of the poor spin I created.

I live in a pretty windy city and I wanted to know what would happen if I'm able to reproduce those 2800 RPM? Would that create 12 volts?

- If so, how can I know the amperage? Because the smartphone needs ~2.1 amps and 5 Volts DC to charge.

- So, If I get those 12 volts, would it be necessary to reduce them to 5 volts? or can I send 5 volts to the smartphone and 7 volts to a secondary battery that I could use later on in order to charge the smartphone when there is no wind?

Note: I could use a smaller fan in order to get those 5 volts.

- Another question is: The wind is not going to be constant, a moment it can have a high velocity and a few seconds later it may not be windy at all so the fan will produce different voltage, Am I right? If so, How can I regulate the output of voltage and amperage in order to not blow my smartphone?

This is by far the main questions I have.

I apologize for my English.
Hope you can help me, guys. Thanks in advance.

#### AnalogKid

Joined Aug 1, 2013
10,951
The fan you have will not work as a generator when the shaft is driven. Some motors do become generators when driven, although they are not as efficient as a device designed from the ground up to be a generator. But what you have is a brushless DC motor. It uses an electronic circuit rather than brushes or other contacts to commutate the coil, an essential part of a DC generator. Even if you opened up the fan ans somehow powered up the switching circuit, it is designed only for being a motor.

If you remove the electronics and connect directly to the stator coils, there should be some current output. but it will be pretty weak.

Also, it is not the case that just because a motor needs 12 V to run, it might produce 12 V when driven. The physics of motors and generators do not work that way.

ak

#### Elboxd

Joined Oct 19, 2015
15
The fan you have will not work as a generator when the shaft is driven. Some motors do become generators when driven, although they are not as efficient as a device designed from the ground up to be a generator. But what you have is a brushless DC motor. It uses an electronic circuit rather than brushes or other contacts to commutate the coil, an essential part of a DC generator. Even if you opened up the fan ans somehow powered up the switching circuit, it is designed only for being a motor.

If you remove the electronics and connect directly to the stator coils, there should be some current output. but it will be pretty weak.

Also, it is not the case that just because a motor needs 12 V to run, it might produce 12 V when driven. The physics of motors and generators do not work that way.

ak
Thank you very much for your response.
I've heard that before (the efficiency part). There is no way to buy the fan with the generator integrated? Just as the one I have but instead of being a motor, it would be a generator. Or do they sell generators only?

I understand the second part. I'm going to do some tests in order to check the Voltage and Amperage output.

I'm thinking about adding that additional rechargeable battery and my question is: If this motor generates 12V of output, can I redirect 5V to the smartphone/tablet and the other 7V to the rechargeable battery? If not, I can use a smaller fan, right?

#### tcmtech

Joined Nov 4, 2013
2,867
Yep you are definitely in way over your head with this concept.

I would recomend doing some reading on wind energy and how much wind speed applied to a specific area it take to make a certain amount of power.

After that do some reading on how generators work and what the definitions of a voltage, amperage, and electrical power are plus how the efficiency of energy conversion from one form to another is factored into all of it.

From there you will need to work on getting a solid understanding of how they relate to each other and how that relates to the input power requirements of a device.

#### ISB123

Joined May 21, 2014
1,236

#### AnalogKid

Joined Aug 1, 2013
10,951
There is no way to buy the fan with the generator integrated? Just as the one I have but instead of being a motor, it would be a generator?
Why do you think someone would build anything like that? What kind of equipment or application would need a device that blows cold air over hot things most of the time, but sometimes is in the presence of such a stiff wind that the fan blades start to turn and the device generates electricity. What would the market be? The world consumes hundreds of millions of small fans each year, and none of then have built-in generators. There probably is a reason for that.

ak

#### tcmtech

Joined Nov 4, 2013
2,867
Oh now I'm staying!!!

So what part of my reply don't you like?

The part that addresses the reality of your ignorance or the part that suggests how to break down what you want into different ares of understanding and so you learn about them and how they all work together?

BTW what exactly is Eolic energy?

Mod Comment: Removed Ad Hominem Attack.

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#### AnalogKid

Joined Aug 1, 2013
10,951
I understand the second part. I'm going to do some tests in order to check the Voltage and Amperage output.
I'm thinking about adding that additional rechargeable battery and my question is: If this motor generates 12V of output, can I redirect 5V to the smartphone/tablet and the other 7V to the rechargeable battery? If not, I can use a smaller fan, right?
1. My guess is that they will be trivially small.
2. The motor will not make 12 V of output.
3. Even with direct access to the coils, it will not make even 1% of the current needed to run a phone. The blades are optimized to be a fan, not a windmill. Completely different aerodynamics.
4. AGAIN, your concept of the relationship between the fan motor ratings and it's potential generator output are woefully uninformed. Even if the motor worked that way - and it does not - the device physics would not do what you want no matter how hard you wished. Consider this. The same size fan is available with motors that run on 5 V, 12 V, 24 V, and 48 V DC, plus 115 and 230 V AC. How does you view of reality account for that?

ak

And watch you mouth. You have received, for free, excellent advice from two different people that answers directly your questions, written for your level of understanding, and have chosen not only to ignore it, but to act like a recalcitrant three year old who needs a nap. You are asking a group of experienced professionals for charity. Show some respect.

#### Wendy

Joined Mar 24, 2008
23,397
They are right. A DC box fan uses a sequencer chip among other things. It is not in the design in the slightest to generate electricity.

You will need a simple DC motor that is not part of a fan to do this, and then connect it to a prop.

Most of us at one stage or another has taken on of these fans apart. I recommend it as a learning experience.

#### Elboxd

Joined Oct 19, 2015
15
They are right. A DC box fan uses a sequencer chip among other things. It is not in the design in the slightest to generate electricity.

You will need a simple DC motor that is not part of a fan to do this, and then connect it to a prop.

Most of us at one stage or another has taken on of these fans apart. I recommend it as a learning experience.
Thank you very much.

I do understand the electronic components within the motor and that it lacks brushes but what confuses me is the fact that there is a video in youtube of a 14-year-old boy that uses a pretty similar fan to mine and is able to generate up to 12V. That's why I'm pretty confused because you tell me that it's virtually impossible.

I have to add that the output is in DC so all I would need is a Voltage regulator rather than a converter.

This is the video (is in Spanish):

#### Lestraveled

Joined May 19, 2014
1,946
temtech gave you good advise. I will give you some more advise, be more humble when you ask for help. Loose the attitude (ego), it is preventing you from learning. If you wish to stand on the shoulders of giants, you must learn how to ask politely.

#### Elboxd

Joined Oct 19, 2015
15
temtech gave you good advise. I will give you some more advise, be more humble when you ask for help. Loose the attitude (ego), it is preventing you from learning. If you wish to stand on the shoulders of giants, you must learn how to ask politely.
Sir, believe me, I asked politely and no, I don't want to "stand on the shoulders of giants"

I'm grateful for all of your responses, please don't misunderstand me, I know that you are going to defend the guy above because he is an older member of the forum than me but, and as I said before, if you'd had a project in my field of knowledge, I just wouldn't tell you that you are "way over your head". I wouldn't try to minimize your ideas.

The Funny thing is that all of the sudden, more people are answering to this thread.

Is not ego, as I said, I just can't handle his attitude.

If something that I said bothers you, I apologize. But please understand that all I wanted was help in electronics, not someone telling me that I'm "way over my head".

#### Wendy

Joined Mar 24, 2008
23,397
You will see many impossible things and scams on the internet, so be careful what you buy into.

The chip inside sequences 6 coils, and the magnet on the inside of the hub is dragged along by the magnetic field. You can generate juice this way, but unfortunately all of it is going the wrong way through a chip that is not designed for that duty.

#### Wendy

Joined Mar 24, 2008
23,397
The guy you are referring to is a semi retired engineer with a pile of experience over you. He donates his time to help people.

You come here asking advice, be aware you need to be polite doing so. The people helping you are not required, and we do insist on manners here.

Eolic energy is not a normal term for wind energy.

#### Elboxd

Joined Oct 19, 2015
15
The guy you are referring to is a semi retired engineer with a pile of experience over you. He donates his time to help people.

You come here asking advice, be aware you need to be polite doing so. The people helping you are not required, and we do insist on manners here.

Eolic energy is not a normal term for wind energy.

God, this will never end, is it?

I'm an aeronautical engineer and work in Airbus for 13 years already. Does that give me the right to talk to anybody the way he did?

Just stop it, if you don't like what I said, just delete my comment and his comment as well, this is getting quite redundant.

Again, if you feel offended, I apologize WITH YOU. But again, as I've already said before a few times, I can't handle people like that. Don't you understand my example? If you don't then tell me and I'll delete that comment myself. Just please, let's focus on electronics.

Again, thank you very much for your responses and kindness.

PD: When I started this thread I apologized for any mistake because English is not my mother tongue.

#### Lestraveled

Joined May 19, 2014
1,946
I think this is a cultural issue. In an American point of view, tcmtech was not being disrespectful to you. I am surprised that a world class aeronautical engineer would have taken insult at what he said.

#### Elboxd

Joined Oct 19, 2015
15
I think this is a cultural issue. In an American point of view, tcmtech was not being disrespectful to you. I am surprised that a world-class aeronautical engineer would have taken insult at what he said.
There is a difference between an insult and minimizing ideas, but what both want to do is to try to make you feel less. It may be a cultural issue, here in France we respect others ideas.

Just please, leave it at that. IF deleting this thread would help, please do. It's becoming quite boring.

#### Wendy

Joined Mar 24, 2008
23,397
What you consider an insult was not, you said it yourself, we are dealing with cultures. Accept it, and your experience will improve.

#### Philip_Freidin

Joined Oct 20, 2015
2
In the link to the video you posted, at 20 seconds in, you can see that the motor he is using
is not the motor that you usually find in a box fan (your picture at the beginning). So he is
using the fan blades and hub from that type of fan, but replacing the motor with a standard
DC motor with brushes.

With experience, you will recognize it just by looking at the case of the motor (cylindrical
grey metal (steel) with pressed in tabs on side of cylinder (holds internal magnets in
position), relatively thin spindle coming out one end, and if we could see the other end
of the motor, we would see two terminals, and some vent holes).

DC brush motors can be run as generators, but they are not designed for that use, and
as others have written, they are not very efficient generators.

I hope this un-confuses you as to why he can generate power with what he is showing.

#### blocco a spirale

Joined Jun 18, 2008
1,546
I'm sure, that as an experienced aeronautical engineer, the TS has already worked all this out for himself.

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