# 12v Wind turbine

#### Alan Garvey

Jun 11, 2017
3
Hi, I was wondering if anyone could help with a slight problem I have with my wind turbine installation. The power is generated through an A/C generator and rectified at the base of my turbine and sent to a 12v battery bank at 13.5v. This is all fine and dandy, apart from the fact that I am in a low wind area and hardly get enough rotation to get past 12v. I was wondering if there was a way to harness all the power generated until a release threshold of 13.5v. Then the power could be released to the battery and I would not have to expect the blades to be turning too fast. Alternatively, maybe 2 6v batteries could be charged in parallel and released at 12v when full. I'm not good with circuits so would need help with any circuit I would need to make.
Thanks in advance for any help.
Best Regards,
Alan.

#### Bluejets

Oct 5, 2014
6,854
Trouble is largely wind power sucks when it needs to blow.
Power out is power in minus any losses so your current 12v charging system appears to be up the creek without a paddle.
You may, as you said, arrange for the alternator to provide enough for an alternative regulator for the 2 x 6v batteries in parallel except for one important point.
You need 12v supply to the rotor and the regulator to function correctly.
Another thought may be to leave the existing system and provide a step-up inverter to charge the 12v battery but again, the rotor requirements come into play.

#### Bluejets

Oct 5, 2014
6,854
As pointed out, it will intefere with the alternator regulator which uses battery pd as a reference and rotor potential.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
The problem is that there is a mismatch between the alternator, the blades, and the wind speed. (And it's largely an impedance mismatch)

The alternator needs to run at a certain minimum speed to generate a useful voltage. Furthermore, it needs to be operating at a higher speed with sufficient torque from the blades to generate it's maximum power.

At a given wind speed, you will require a certain swept area to get a given power (allowing for a stack of conversion inefficiencies). In addition, the configuration of the blades needs to be such that they will give the required rotational speed.

And after all of that, you need intelligent control to maximize the per available to charge the batteries.

Typically the swept area is constant, so if this is insufficient, there's not a lot you c can do.

If you can control the blade pitch or the field current you have additional methods of control. In a small setup you probably don't, so an MPPT regulator is the remaining option.

Since you have AC, the MPPT regulator could be a servo controlled autotransformer, but these days a DC to DC converter with microcontroller control is typically used.

#### Alan Garvey

Jun 11, 2017
3
I've taken all your points into account and it seems that the problem is I don't have a constant voltage. But the wind lately is so slow that I can pretty much guess that the blades will never reach more than 6v of generating power. I'm sure some kind of controller with a value of say 4v would cope with an excess of 2v fluctiation over that. Below 4v it would never kick in. What do you think? Could I have a DC to DC converter from 4v to 14v?
Please explain what a microcontroller control is and do I need it?

#### Bluejets

Oct 5, 2014
6,854
Basically a microcontroller takes sensor inputs and depending on the internal program, turns on or off external devices. Your problem is as outlined in the beginning of my other reply ie you simply do not have enough grunt and no added piece of anything is going to help short of a set of blades the size of a 747.

#### Alan Garvey

Jun 11, 2017
3
I see. So if I convert 4v to 14v then the wattage would not be enough. That's understandable. I did see this on ebay http://www.ebay.co.uk/itm/Adjustabl...611747?hash=item1a2cd9a8e3:g:~i0AAOSwa~BYObtt
It has a wide fluctuation range. But I can see now that converting 4v to 14v must have some serious losses.
Just noted that the input current for this device is 3A. That would mean 3 X 4 = 12 watts. If I measured 12 watts while the blades were turning then it would be viable. Although it says 12v (max), sorry just seen that.

Think I've decided that it's not viable after all. Will just wait for a hurricane. He, he, he

Last edited:

#### davenn

Moderator
Sep 5, 2009
14,233
Just noted that the input current for this device is 3A. That would mean 3 X 4 = 12 watts. If I measured 12 watts while the blades were turning then it would be viable. Although it says 12v (max), sorry just seen that.

that's just the max it can take before failure is likely to occur

your input current could be much less than that, so the rest of your comment doesn't mean much

#### 32Vwasbetteronboats

Feb 18, 2017
80
Maybe if you scale up in size a A continuously variable transmission (CVT) from a motorscooter keep your generator RPM consistent.

Something from the Centrifugal governor idea

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