Project: Charging devices with Eolic Energy

ScottWang

Joined Aug 23, 2012
6,926
The forum was created for study and sharing the ee acknowledge from each other, not fighting for personal in different ways, if you still using the offence language again, then our mods will give you ban for a several days to let you calm down, please to be nice to someone who trying to help you and to keeping a good mood for the forum, thanks.
 

Kermit2

Joined Feb 5, 2010
4,162
Your swept area. The size of your fan, will limit your power to about 50 watts in a very strong wind. On average, with a 15 mph wind you will generate about 20 watt hours with a rotor of that small size and losses due to conversion of a DC motor into a generator.

To supply the recharging needs of your phone you must increase the size of your fan blade in order to capture more wind energy. This will also require that your motor/generator be increased in size.
 

GS3

Joined Sep 21, 2007
408
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):
There are several point you need to understand. In that video the kid is not using the original fan motor but a different type of motor with brushes and using a hair blower, which means he is using an air speed you are not going to find anywhere where you are normally sitting, he is generating up to 12 V without load, which means zero useful or usable power. Zero. Connect a load and that voltage sinks like a stone. That video just show a basic concept and is not anything useful. Probably the boy's next assignment is to show he can put some voltage into the DMM by sticking two wires into a lemon.

If you want to get any useful energy from wind, even a small amount, you need to start thinking differently and definitely bigger. You need to put something high up in the air and start thinking of a blade set at least 50 cm in diameter. With good wind you might get a tiny amount of power. Still, it is going to be complicated designing the blades, finding a suitable generator and putting it all together.

Note that wind turbines will typically start getting some useful output at 35 Km/h wind and become really productive at 55 or 60 Km/h. That is a lot of wind which is just not happening most of the time and certainly not in your living room or yard. A poorly designed turbine (or one designed for a computer fan) will perform even worse.
 
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GS3

Joined Sep 21, 2007
408
Your swept area. The size of your fan, will limit your power to about 50 watts in a very strong wind. On average, with a 15 mph wind you will generate about 20 watt hours with a rotor of that small size and losses due to conversion of a DC motor into a generator.

To supply the recharging needs of your phone you must increase the size of your fan blade in order to capture more wind energy. This will also require that your motor/generator be increased in size.
Something is wrong here. There is no way in the world that fan is going to generate 50 or even 15 watts. And if it did that would be plenty to recharge a phone.
 

tcmtech

Joined Nov 4, 2013
2,867
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?
So as an aeronautical engineer I would think you would be familiar with how to calculate basic wind energy values given basic wind speeds and how they would relate to the Betz laws on converting said energy into mechanical motion and how the aerodynamics of a blade for making wind and one that catches wind are totally different and see the basic problem with using your fan as a wind generator.o_O

It also seems odd to me that for someone who has worked as an engineer at Airbus you could have so little understandings of basis electrical principals like volts, amps and watts given the huge amount of electrical and electronics that they incorporate into every aspect of their design. :rolleyes:

Lastly I assume you use written documents to communicate fairly often so the overall neutrality of the wording I use should have been pretty obvious. Unless of course you are just verbally baiting me which if so you had better be a master at it if you want to get me upset. You are not a verbal master baiter are you? :confused:

How's that for talking to you now?:D

Now as for your original fan being converted into a wind generator it would work with some moderate motor circuitry modifications but given your charging requirements of a stable 5 volts @2.1 amps you will need a source that can supply a stable minimum power of 10.5 watts which to be honest my quick references to wind power and what I do know of those fans and their motor designs I would say that unless you have 80+ MPH (~128+ KPH) winds you won't get more than a watt at best from that fan once converted over to be a wind generator. :oops:

Personally I would recommend having someone at Airbus design you a basic wind catching airfoil (that best matches your power requirement after conversion losses are factored in to the average wind speeds you have in your area) that you carve it out of a piece of wood and use that to spin a low speed brush type DC motor to charge a 12 volt battery and then use a common automotive USB power adapter to take that battery voltage and convert it down the the 5 volts and 2.1 amps you need. ;)
 

Kermit2

Joined Feb 5, 2010
4,162
My calculation was an estimate on WIND ENERGY available with a blade radius of 3 inches.

You are correct that generated DC power would be much smaller.

The 20 watt estimate assumed a 15 mph wind and a generator with 80% conversion efficiency.

Read what is posted and I won't have to repeat myself like this.

Don't argue with me...do the math yourself and post your results here.
 

Thread Starter

Elboxd

Joined Oct 19, 2015
15
What you consider an insult was not, you said it yourself, we are dealing wways cultures. Accept it, and your experience will improve.
I was not aware that I denied it at any point. I'm the first asking to leave it at that and concentrate on electronics. Please!

I'm sure, that as an experienced aeronautical engineer, the TS has already worked all this out for himself.
As you can see, I'm having a bit of a hard time here. And please stop with that kind of messages, if you are not going to say something productive please don't comment. As some people say: "The forum was created for study and sharing the ee acknowledge from each other, not fighting for personal in different ways" if I would like to have someone telling me that I'd be working with you and it's not the case.

The forum was created for study and sharing the ee acknowledge from each other, not fighting for personal in different ways, if you still using the offence language again, then our mods will give you ban for a several days to let you calm down, please to be nice to someone who trying to help you and to keeping a good mood for the forum, thanks.
What are you talking about? I'm the FIRST ONE along to leave it at that and some more people came and keep commenting about what happened. Those people are the one that can't just let go. You've eliminated the first comment. Explain the part "if you still using the offence language again".
A few here started focusing on the electronic part until the two guys quoted above of you in this comment kept talking about that. I didn't say ANY MORE SO JUST FOR THE LOVE OF GOD, LET GO!
 

Thread Starter

Elboxd

Joined Oct 19, 2015
15
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.
This really helps, thank you very much.

I didn't see the motor part, hence my confusion.

I have found I site where sell motors and I was wondering if they would be better for this: http://www.nmbtc.com/brush-dc-motors/engineering/select-flat/

What are your thoughts on this?

Thanks again for your reply.
 

alfacliff

Joined Dec 13, 2013
2,458
there are some small fans tht use brush motors that will generate some voltage. the ones that will nt generate are the kind with electronics inside. if you have an ohmeter, the brush type will read low resistance. if you have a volt meter, when connected it will show some voltage when you spin the motor the electronic type have a circuit that simulates ac for the motor, and will not allow any generated voltage to go back out of the fan when it is turned. with an ohmeter, they show very high resistance.
 

ScottWang

Joined Aug 23, 2012
6,926
...
What are you talking about? I'm the FIRST ONE along to leave it at that and some more people came and keep commenting about what happened. Those people are the one that can't just let go. You've eliminated the first comment. Explain the part "if you still using the offence language again".
A few here started focusing on the electronic part until the two guys quoted above of you in this comment kept talking about that. I didn't say ANY MORE SO JUST FOR THE LOVE OF GOD, LET GO!
Although we deleted the post, but what you said the system had the record, you should remember that, if you want us to show what you said, that is not good for you, if anyone insult you, you can't and not necessary to fight back, this is not a war here, you just press the report button to do what you should do, or if you insult other members, our mods team all will dandle it, we just want to keeping the forum have a good mood to discussing the ee issues, if you want to fight, fight for the ee theories, no bad words here, thanks
 

Marcus2012

Joined Feb 22, 2015
384
Please do correct me if I am wrong but don't wind turbines usually have a gearbox to turn low RPM, high torque to high RPM, low torque as wind speed is rarely fast enough to create such high RPM needed for generation?
 

Thread Starter

Elboxd

Joined Oct 19, 2015
15
Your swept area. The size of your fan, will limit your power to about 50 watts in a very strong wind. On average, with a 15 mph wind you will generate about 20 watt hours with a rotor of that small size and losses due to conversion of a DC motor into a generator.

To supply the recharging needs of your phone you must increase the size of your fan blade in order to capture more wind energy. This will also require that your motor/generator be increased in size.
Thank you for your response.
So if I would generate 20 watt hours with a rotor of this side, would that be enough for charging the smartphone? As far as I know a smartphone uses 5 watt hours, right?

What are your thoughts on this type of motors:
http://www.nmbtc.com/brush-dc-motors/engineering/select-flat/

Would those ones help?

There are several point you need to understand. In that video the kid is not using the original fan motor but a different type of motor with brushes and using a hair blower, which means he is using an air speed you are not going to find anywhere where you are normally sitting, he is generating up to 12 V without load, which means zero useful or usable power. Zero. Connect a load and that voltage sinks like a stone. That video just show a basic concept and is not anything useful. Probably the boy's next assignment is to show he can put some voltage into the DMM by sticking two wires into a lemon.

If you want to get any useful energy from wind, even a small amount, you need to start thinking differently and definitely bigger. You need to put something high up in the air and start thinking of a blade set at least 50 cm in diameter. With good wind you might get a tiny amount of power. Still, it is going to be complicated designing the blades, finding a suitable generator and putting it all together.

Note that wind turbines will typically start getting some useful output at 35 Km/h wind and become really productive at 55 or 60 Km/h. That is a lot of wind which is just not happening most of the time and certainly not in your living room or yard. A poorly designed turbine (or one designed for a computer fan) will perform even worse.
Thanks for your response.
My bad I didn't see that he was using a different motor.
My question is why would that voltage sink?

Let's say I have winds of 60 km/h for at least 5 hours. Almost a constant velocity. With the current system, how many volts could I storage in a rechargeable battery?

What are your thoughts on this kind of motors:
http://www.nmbtc.com/brush-dc-motors/engineering/select-flat/

Thanks again.

Something is wrong here. There is no way in the world that fan is going to generate 50 or even 15 watts. And if it did that would be plenty to recharge a phone.
True.

My calculation was an estimate on WIND ENERGY available with a blade radius of 3 inches.

You are correct that generated DC power would be much smaller.

The 20 watt estimate assumed a 15 mph wind and a generator with 80% conversion efficiency.

Read what is posted and I won't have to repeat myself like this.

Don't argue with me...do the math yourself and post your results here.
I do get the confusion because you said: "The size of your fan, will limit your power to about 50 watts in a very strong wind."
 

Thread Starter

Elboxd

Joined Oct 19, 2015
15
Although we deleted the post, but what you said the system had the record, you should remember that, if you want us to show what you said, that is not good for you, if anyone insult you, you can't and not necessary to fight back, this is not a war here, you just press the report button to do what you should do, or if you insult other members, our mods team all will dandle it, we just want to keeping the forum have a good mood to discussing the ee issues, if you want to fight, fight for the ee theories, no bad words here, thanks
Please, just leave it at that. Let's focus on electronics. Can we?
 

Kermit2

Joined Feb 5, 2010
4,162
You simply need a larger blade (swept area) to extract enough power for your phone.

Like I said there is about 20 watts of energy in a 15 mph wind across your blade diameter of 6 in.
You CAN NOT extract more than about 50-60 percent of that with a PERFECT wind generator.
A real generator will extract about 25-40 percent of the power.
So, you could get around 5 to 8 watts using a very efficient generator and those 6 in. Dia. Blades

You need bigger blades on the generator. Period.
 

AnalogKid

Joined Aug 1, 2013
8,532
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
No, it isn't. What confuses me is that he uses a completely different motor and you can't see that. I pointed out in post #2 that some motors can be used as generators, but yours cannot.
His can. Yours cannot.
He does not use the motor in the fan.
Not at all.
He does not use it.
No, he doesn't.

He uses a permanent magnet DC motor that has brushes.
His motor has mechanical commutation brushes.
The fan motor does not.
It is called a brushless motor because it does not have brushes.
There are no brushes or other mechanical commutation in the original fan motor.
The original fan motor can not be used as a generator.

Are we there yet?

ak
 

AnalogKid

Joined Aug 1, 2013
8,532
Elboxd: When I started this thread I apologized for any mistake because English is not my mother tongue.

Les: I am surprised that a world class aeronautical engineer would have taken insult at what he said.

me: I am surprised that he is trying to sell us that f*** was an error in translation. I'm not surprised that he is surprised that no one is buying.

AND - I've been doing electronics for money for 50 years, and I'm not even close to the oldest or most experienced guy on this forum. Still, if I were on a mechanical engineering forum with a question, I wouldn't be throwing F-bombs at total strangers. That way lies folly.

ak
 

tcmtech

Joined Nov 4, 2013
2,867
Like I said there is about 20 watts of energy in a 15 mph wind across your blade diameter of 6 in.
You CAN NOT extract more than about 50-60 percent of that with a PERFECT wind generator.
A real generator will extract about 25-40 percent of the power.
So, you could get around 5 to 8 watts using a very efficient generator and those 6 in. Dia. Blade.
Here's what I go by http://www.engineeringtoolbox.com/wind-power-d_1214.html and their calculator says you are off by a factor of about 10 times too high in practical application.

Given a ~15 MPH wind speed ans a 6" dia blade set the numbers they come out with are ~1.6 watts assuming a very generous 50% conversion efficiency.
Realistically given the blades are wrong and those tiny brushless DC motors are pretty weak when made to work as a generator I stand by my estimate that he would need a 80+ MPH wind to get his 10.5 watts of charging power from one once all the conversion losses are factored in and a very generous assumption that one of those little motors could even produce that much power to begin with.

Realistically I would say a ~2.5 foot (.75 meter) dia blades set driving a 20 - 30 watt stepper motor as a generator in ~15 MPH (24 KPH) winds would give him enough usable power to charge a battery that could be used to charge his phone using a USB power adapter in between.


But what do I know, I'm just a mean jerk. It's not like I haven't played with DIY wind power and electronics for over 2.5 decades of my life now. :rolleyes: :p
 
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Kermit2

Joined Feb 5, 2010
4,162
Well snit.

I too, get a different answer when I use pi X radius[2]

Instead of pi [2] X radius. Oops! :) got cut on my rusty math, so now I need a tetanus shot.
 

Thread Starter

Elboxd

Joined Oct 19, 2015
15
Nothing personal but this forum is quite toxic... Let me show you some examples:

My calculation was an estimate on WIND ENERGY available with a blade radius of 3 inches.

Read what is posted and I won't have to repeat myself like this.
Don't argue with me
...do the math yourself and post your results here.
And then he realizes his mistake and tries to apologize with an "Oops!" after being pretty arrogant. That is just so annoying and disgusting.

NOTE: I'M NOT BEING RUDE OR CURSING, I'M JUST STATING THE FACTS.

I wonder why can't you just talk without sounding arrogant or pedantic.


No, it isn't. What confuses me is that he uses a completely different motor and you can't see that. I pointed out in post #2 that some motors can be used as generators, but yours cannot.
His can. Yours cannot.
He does not use the motor in the fan.
Not at all.
He does not use it.
No, he doesn't.


He uses a permanent magnet DC motor that has brushes.
His motor has mechanical commutation brushes.
The fan motor does not.
It is called a brushless motor because it does not have brushes.
There are no brushes or other mechanical commutation in the original fan motor.
The original fan motor can not be used as a generator.

Are we there yet?

ak
Another one... I'm not a 2-year-old boy nor I have a mental problem. I do understand that and I stated it in the post number 32:

Thanks for your response.
My bad I didn't see that he was using a different motor.
My question is why would that voltage sink?

Let's say I have winds of 60 km/h for at least 5 hours. Almost a constant velocity. With the current system, how many volts could I storage in a rechargeable battery?

What are your thoughts on this kind of motors:
http://www.nmbtc.com/brush-dc-motors/engineering/select-flat/

Thanks again.


You should read mate.

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

Les: I am surprised that a world class aeronautical engineer would have taken insult at what he said.

me: I am surprised that he is trying to sell us that f*** was an error in translation. I'm not surprised that he is surprised that no one is buying.

AND - I've been doing electronics for money for 50 years, and I'm not even close to the oldest or most experienced guy on this forum. Still, if I were on a mechanical engineering forum with a question, I wouldn't be throwing F-bombs at total strangers. That way lies folly.

ak
I'm not trying to sell you anything, in fact I don't care about what you think but I must correct your ignorance.

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

I was talking about the "Eolic Energy-Wind Energy thing". I don't know why would you think that I was trying to sell "GTFO" thing as a mistake. Maybe some reading problems. Understandable.

And about the forum thing: Good for you mate. Are you chill now? Can we proceed with the electronic project? Great. Buckle up.
 
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