Installing the Turbine

Well after a long delay I finally got the turbine up on the garage roof.

In spite of all my previous design advice I over engineered my turbine.

It became quickly apparent that the design was far too powerful for the blades. Even in a pretty solid breeze, the turbine would not come up to speed due to the resistance of the coils as they tried to generate power. Adding extra resistance to the load helped but it is not a good solution.

The voltage of a wind turbine is determined by
1. magnetic strength,
2. number and thickness of coils and
3. rotational speed.







The latter is all we can control. Unless of course we redesign the turbine.

It is important to understand that voltage is very important, in fact even more important than power (current). Without the required voltage, batteries simply can not be charged. Lead acid batteries need a minimum of 2.25V DC per cell to charge. Times six = 13.5 Volts minimum to charge a 12v lead acid battery. Below that nothing happens. No charging, nothing.

Most literature suggests that you charge a battery to 14V DC so you need at least that and a bit more for overhead with a control circuit to switch off charging when say 14v DC is reached.

I decided to approach the problem differently. I could increase blade size/diameter or even make another set of coils or even remove half the magnets.

But why not use the over engineered turbine to our advantage.

We found that by running all coils (five) it was too much for the blades to rotate but it did provide great protection against high winds by providing a high level of braking.

If we could engage coils depending on wind speed than we could maintain our voltage and bring in coils as the wind increased to provide more power.





This would need a small PIC computer to control it but if it worked would be a great solution.





But first to test. Originally I had the bridge rectifiers mounted behind the turbine and passed one heavy wire down the centre of the turbine. This was + Positive. I connected the - Negative to the turbine at the top and used the tower as my ground.

I have now cut the connection from the coils to the rectifiers and connected a wire to each coil (5) and ran the five wires down the centre of the turbine.



I then built a rig that would allow me to switch in and out manually each of the coils.




Have a look at the rig. I had an old bit of aluminium lying around (old tail fin) so I cut some holes for lights and switches.


I used 50W downlights as loads, each pair in series to allow for 24v DC.

I ran coils 1 and 2 straight to a bridge rectifier and into the "Normal load" of two lights in series. ie 24 v and 100W



I then had a switch for the three remaining coils which I could switch to a bridge rectifier and
then onto the load individually.


I included a fourth switch that switched in the second set of lights in parallel . This would effectevely halved the resistance and doubled the load. i.e. a good brake.

See the back of the control board. Wires from coils to switches, switches to rectifiers and output or rectifiers all common to plus Volts and ground (blue). Aligator clips on AC input of first coil to measure Hertz or RPM.

RPM needs to be devided by 8 as there 16 magnets giving 8 cycls per revolution.