series two turbines together

[Jason Wilkinson]

 My friend has lost his inverter   (aims 2500 watts) he has now magna sine 4024
panels are configured from 12v to 24v.  but the two turbines are 12v 
 He " somehow"  tried to put them in series .  What i've seen is with a good gale both put out power
 but as the wind drops one slows down to the point where it almost stop while at the same time the other seems to overspeed.
   Apart from building two new 24v stators , is there any way these two 12v (10 footers)  can be made to work at 24 volts ?
  Jason

[Flux]

Series operation is not going to work.

In a gale I suspect both would have worked on 24v individually better than in series. The problem will be that the low wind performance will probably be poor or useless.

The real options are boost converters, step up transformers or new stators. In the unlikely event that the stators are delta connected there would be the option of changing to star.

Another option that may work but is not without problems is to connect one turbine to each half of the 24v battery so that each is charging 12v. The big snag here is that the charging may be too unbalanced and the batteries get out of step. There are equalizer devices available that keep the batteries in step and this would work perfectly well, not sure how the cost would compare with new stators.

If the wind contribution is not large compared with the solar it might just work well enough anyway if the batteries are equalised regularly. Watching the voltage sharing or sg of the 2 halves of the battery would be needed. Depends on the desire for manual intervention.

Flux

[Jason Wilkinson]

Thanks Flux,  my pal feels if both gen were on the same shaft they would work  ( i don't know) .
And yes,in the high winds they both charged the batt  working individually, but as whe wind drops ?  looks like he'll have to wind new stators  at least one for now
ps is there any merit /gain/point in salvaging the wires in them both to make one stator  or do we look for new wire ?
 Jason

[Flux]

Yes he is right, if both were on one shaft it would work. Having wind turbines in series is a bit like solar panels in series with one shaded. With wind the problem is so much worse as both turbines never see the same wind at the same time.

I am not sure how your stators are made, if they are axial flux machines and potted in polyester resin it may be possible to salvage the wire. If potted in epoxy then probably not. If they are iron cored machines then it is unlikely that you will be able to reclaim the wire.

Even if you do manage to reclaim it, it may not be much use as you need twice as many turns of half the csa wire, it is very unlikely you will have room for twice the turns of the same wire. Unless the original was delta there is little way round it going from 12 to 24, you would have more options going the other way.

To be honest you will save a lot of effort and frustration by going for new wire. You need half the csa, if using the AWG system then 3 numbers less. Wind with twice as many turns or perhaps 5% less than twice as the diode drop and line loss will be less at 24v, especially if the original machines showed any hint of stall.

Flux

[Patrick Lemaire]

The problem is potentially your doubling the voltage. The windings inside your windmill may not be able to handle the voltage.  Either the copper wires are too small or the isolation on the windings to thin.  I suspect one of the windmill is fried...