Wind turbine Savonious Charger based on Joule Thief - advise for a charger?

falexandru:
Phase two: generator.

Firs fail: the toys motors cant supply the current I need to light the LED in the Jule thief circuitry I made.

Capacitor 10uF to motor terminals may help, why you not connecting LED directly to motor ?

I will mount a 10 uF to the motor.

Few months ago, a friend of mine mounted an white led to a PC fan. It lighted.

The wind turbine is part of the combined generator, that includes the PV charger (separate thread) and perhaps an energy harvesting module in a later stage.

Therefore, the wind, the Sun etc. will all charge the same battery. And the battery will supply current to the LED.

Modular design. :slight_smile:

falexandru:
I will mount a 10 uF to the motor.

Few months ago, a friend of mine mounted an white led to a PC fan. It lighted.

That is my question in post # 46.
If LED is not lighting reverse connection of it.
Basically any motor with magnet should work

I reversed the connections of the toy motor with no result. Maybe I shall check the wiring, connections again.

Ill check mounting the LED directly to the motor, to "debug" :-)).

The motor my friend used was a PC fan one, which is far lower rpm than a toys motor.

I randomly pick up a few motors and speed them quickly by hands, and the LED is always lighting, if is not I change rotation direction.
Jule thief required pure DC, from motor you don't have that.

Then I have to make sure I get a pure DC from my generator.

Maybe using the same concept of Shotky + Zener as in the case of Photovoltaic charger? But the problem is now how to regulate 1 V, in absence of this value in the Zeners range.

And is also more problematic because the available power is much less than in the PV case, I dont like to throw current away.

I came across LT3022, which is manufactured by Analog, which is stated to regulate as low as few hunderd miliV. Looks interesting, although not in line with my "simple design" rule.

Another interesting idea is to use a supercapacitor. Then the motor will charge the supercap and the supercap will charge the battery via Joule thief- in order to reach the required voltage to charge the NiMH (or LiIon).

A nice point in this approach is that I can charge the capacitor during night and discharge it daytime. Or using 2 of them, each for 12 hours.

+++

I searched the internet about supercaps as chargers but no result so far.

I suppose no matter the voltage (usually 1-3 V, very variable), the cap will charge anyway. Then the problem is how to gradually discharge the supercap into the battery.

How about not to use Joule thief, battery will be charged without it ?

OP really needs to look at the physics of what they are trying to achieve.
Small DC motors simply wont work for this kind of application as they are designed to spin
really fast, usually in the thousands of RPM, and a vertical vane wind turbine will simply not spin this fast, no matter what.
You will be lucky to get a few hundred RPM from one .
Small wind turbines use a special type of alternator, usually a 3 phase permanent magnet type with very strong Niobium magnets to get a sufficiently high magnetic field to allow the turbine to produce usable voltages at low RPM.
Do some research on small vertical vane wind turbines and the types of generators they use.

Motor like this gives 2.5V @ 500 rpm ( speed of my drill)

@ted

I am not a fan of Joule thief :-).

I did not find any other simple circuit (on other words - no integrated circuits) to rise the voltage from some 1V to more than 3V.

@Mauried

This is a demo project. Efficiency is far less important than simplicity.

I am considering a brushless motor.

The issue isnt efficiency.
Its all about getting sufficient volts from your motor at the speed the turbine will turn it.
You need to calculate or measure how fast the turbine is going to spin via whatever method you use to spin it , and then source a motor that will provide sufficient volts to light your led at this speed .

From this motor at high speed I have 12V - post # 55

How pure is "pure"?

When I spin my motor I increase the speed in few seconds, keep the hair dryer at (relatively) constant distance to the motor's propeller for few seconds and then turn the dryer off.

I think in real life that might be some wind bursts but the reason why I choose the vertical axis turbine is exactly the fact that in the target area the wind speed is usually 1-2 m/s.

It is something confuse in all this. Why the Joule thief cant work on variable voltage? Or, at least, how much variability is OK?

If I mount a capacitor (as advised) to the motor, then some sort of equilibrum between the current sent to cap and the current sent to Joule could be achieved. That is my understanding, but I may be wrong.

A joule thief can offer higher voltage even when closing and opening the circuit by a push button. Why it cant do the same when the voltage varies with the wind speed?

@mauried

Think to the project as a sort of "close garage challenge": I have only usual components: a handful of diodes and transistors, resistors, wires. That is fun and is also learning.

I have a toy motor in my hand. No Hall sensor or similar. How can I measure the spinning speed? We have to imagine a method. What I have in mind is to place two wires ringshape near two sides of the motor and measure the current by an multimeter. Or use some sort of optical method. Lets be innovative and imaginative.

Good engineering is simple engineering. Exceptional engineering is fun engineering. :slight_smile:

To answer your question you need to look at oscilloscope, If motor capacitor does not help you need a bigger motor.

try bigger capacitor.

OK, I will mount my (portable) ossciloscope to motor terminals (cap added) and spin the rotor by hair dryer.

I also got my brushless motor today. But I need to make a circuit (6 Schottkys is the simpliest I could find) to milk DC out if it, as far as I know.

Make a picture what you see on oscilloscope.

falexandru:
Here it is the pic:

  • background: the circuit which works ok
  • grey ferrite ring - which does not work (wired)
  • blue ferrite ring which does not work

The length of the wires in blue and grey cases were 80 cm and then 40 cm.

The length of the wires in the white ferrite ring 30 cm.

You might have better luck with magnet wire, and with smaller toroids [so the windings are closer together, and more compact].

Also, [referring to another post] on those motors/generators you said "don't work", did you attach a meter to them to see if they are outputting anything [and whether your getting AC or DC]?

And whenever you say "it didn't work", I think, what does that mean. Why do I think that? Because, I don't know for sure if your aware of the concept of "a multitude of variables". It would be more informative if, instead of saying "doesn't work", you told us what the "failure mode" is. Even if it seems obvious or redundant. For instance, when you were trying the various cores [toroids], did you just hook it up, then decide it wasn't working if the LED didn't glow, or did you try reversing the wires on the primary [or secondary] to give it another try...then, even after that, did you check to make sure the power source was adequate/functioning/consistent -- i.e. with the goal of limiting variables as much as possible. And, in case you don't know what I mean by variables: The power source is a variable [in fact power source voltage is a variable, power source consistency is a variable, power source current capability is a variable], proper inductor hookup is a variable, LED polarity is a variable [i.e. is the LED connected properly]. If any if these variables are not consistent -- if more than one fail at a time, and if those failures are not consistent, then you can easily be misled.

One example of limiting variables is to use a Bench Power Supply when doing something like, testing Toroid Cores to see if they "work" or not. A bench power supply is far more likely to be consistent, than, say, a motor being used as a generator. Test the toroids with the bench supply, with parameters set to as closely model the real world power source [whatever that winds up being], as possible, then, when you have a set of cores that worked with the Bench Supply, you can have more confidence that if, when you try them with the real world power source, when they fail, it has more to do with the real world source.

Another example: when trying different power sources, use the same Joule Thief setup, each time.

If you try to "save time" by testing a bunch of things at once, when things don't work, it's hard to be sure what the source of the failure is.

@ReverseEMF

Thank you! You are right!

I guess is the time to plug in my power supply and to use a more consistent vocabulary to a more detailed description.

Unfortunately, the OlyMEGA forum is currently down for upgrades. I took apart a bunch of old CFLs and scavenged toroids out of them, and wrote up with pictures how to properly phase the coils.

The dots are for transformer phasing. With a bifilar winding such as you have there (ie, the two wires are twisted together), the matching ends will have the dots on them. Basically, when an AC signal is on the positive half going in, the same end of the secondary will also be on the positive half.

From your picture, you have the windings connected correctly.