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Some questions about my 12v wind turbine project Answered

Hi! My name is Ashaz and I am 14. I am making a 12v wind turbine for a project at home. I am using ideas from various sites including YouTube and Instructables.

I have some questions.

1) I want to charge a 12v battery but want to prevent overcharging. Should I buy this to make sure it stops? It says I need a 220v input.

2) If I was to buy the module, how do I use it? The instructions are a bit hard for me to understand.

3) I want to keep costs low so should I go for a cheaper motor than the XD-3420?

Thank you for your help in advance.


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Josehf Murchison
Josehf Murchison

1 year ago

That circuit wouldn't work for what you want, that circuit turns a transformer on and off to charge the battery and stop charging.
Even though this is a solar charger module you want something more like this.
As for the motor I would go for an axial flux generator you can build yourself. it will work better than a motor.

Jack A Lopez
Jack A Lopez

1 year ago

I think it is premature to worry about overcharging a 12 volt battery, or even to worry about charging a 12 volt battery, before you have a power source capable of doing this.

I think the way to do this, is to start with a wind turbine and a generator, and then try that with some different sized resistive loads, to get a sense of how much voltage and current your generator can supply.

I mean, the voltage output for this kind of machine, a permanent magnet motor, is NOT going to be constant. Instead it is going to have a open-circuit voltage, roughly proportional to how fast the shaft is spinning. Also the voltage while supplying current, will be lower than that, perhaps by a voltage drop equal to the current multiplied by the resistance in the windings. Or, well, that is just a guess.

Regarding the permanent magnet DC-motor-generator you mentioned, XD-3420, I never heard of that one, but I looked it up via DuckDuckGo,


and I found some prices here,

and here,

This looks like a good price to me, for the amount of power throughput (max 30 watts). Curiously, it looks like this seller, Banggood, is selling the same motor at two different prices, 19.38 USD, and 16.30 USD. That is what this site is telling my browser, at the time of this writing.

The pictures of these motors look slightly different too, at those different links. In particular the cheaper priced one appears to have some threads, and a hole, in its shaft. Those features might be helpful, depending on how you are planning to connect this shaft to your turbine.

Although, heaven only knows what will actually show up in the mail, if you buy one of these things.

Regarding what I was saying about open circuit voltage being proportional to speed, did you notice the little table with the words:

Voltage Speed
DC12V 3000RPM
DC24V 6000RPM

This kind of suggests the expression,

voltage = (1 volt/ 250 RPM)*speed

The open circuit voltage, seen at the terminals will be something close to this. For example, 2.0 V, when spinning at 500 RPM, 4.0V when spinning at 1000 RPM.

The next thing I am wondering about, is how fast (in RPM) can your wind turbine make a shaft turn?

By the way, since you have not bought a generator yet, this might be a number to consider, when shopping for such a generator. You know, try to estimate how many volts you will get, per RPM of shaft turning speed.

The final thing I wanted to mention, is to not get discouraged when the explanation seen in an eBay listing for some module or gizmo, seems confusing or incomplete. Usually it is because the seller's explanation is lacking. That same battery protector, is being sold by some other eBay seller, here:


and that different seller was thoughtful enough to draw a wiring diagram, showing more of the complete picture... which includes a mains powered DC supply, that gets shut off via the relay on that board.