THE FORUM IS NOW AT buildyourownwindturbine.com

Hi I started winding the coils for our 3.6m turbine using 35 turns of 1.5mm 3 in hand. It's going to be 24v I would like 48v but would have to upgrade our batteries and they are only new hoppecke opz 600 at a price of 4200 euro and we can't aforde the same again also if we added another 12 batteries the AH would be 800 at 48v and that's to much for us.


So here is the first photo the coil winder setup.

Any one have any tips on joining the 3 wires together they seem a bit bulky I saw on otherpower that they used strips of copper and crimped them and then soldered.

......................................................
Sunday 4th Nov 07
Coils wound and ready for soldering I made two bad ones one was to loose ant the other one was to light I must have miscounted it is a good Ida to weigh them.

The coloured tape is to help me with the wiring.

Hi Jimmy, the 35 turns will run pretty fast at 24 volts so I won't be great in low winds but it will be good at the top end with less tendency to stall the blades and good efficiency and less heat in the stator.

Crimping first would be good but probably not entirely necessary. Another way to do it is to tin the wires, lay them together and wrap them tightly with a smaller diameter wire before reheating and finishing the solder join.

A friend sent me this description of how he tins wires with a crucible and the hot solder melts off the coating. It sounds a bit scary to me.

"Another thought. About soldering wires to join coils. I find scraping somewhat fiddly and burning off the enamel insulation seems to make it clag on even tighter.
Most "magnet wire" is now sold as "solderable" but it requires a much higher temperature than for normal soldering. Solder pots are expensive so I have made one at trivial cost.
I cut a length of copper tube then flatten one end to make it leak-proof. Drill through the flattened part and fit a handle. Fill this crucible with solder and melt with a blow torch. It needs to get up to a high temperature but eventually you find that dipping small pieces of wire into the molten solder will result in a nice bright tinned surface.
I then tin all coil ends to be soldered and join them with a soldering iron. Works well!"

You might want to try it but I would not blame you if yo ujust scrape off the enamel instead :-)

Thanks Hugh I must have misunderstood your advice on the stator is their anything that can be done like bigger blades or high grade magnets that will make it do the opposite as we live I a low wind area.

I thought I had suggested 40 turns - maybe I forget but that's what makes sense to me. Seems like you could fit 40 turns of 3 in hand 1.5 mm diameter wire. sorry if I confusef you somewhere along the line.

Yeah well I wrote in haste earlier today.

I found the message where I suggested 35 turns now. What i said was that you could use 35 turns of 1.5 for high speed, or 40 turns for low speed and thinner wire. When I wrote the above earlier today I did not spot that the 40 turns would be 1.5 sqmm which is 1.4mm diameter, and not 1.5 diameter as I thought in haste.

It's getting pretty muddly altogether and I think I have a handle on it at this moment so I will spell out a few things of interest to all I hope.

The Gyreum machine had 110 turns for a 48 volt output (single wire 1.5 diameter) but you may remember that I had to jack the magnets a long way apart to get the right speed. I was looking for about 120 rpm cut-in for 48 volts output.

I would now recommend a smaller number of turns, say 80 for the 48 volt machine (using 1.7 mm diameter) or 40 for the 24 volt machine (using 2 in hand 1.7 mm diameter). I thought Jimmy had a stock of 1.5 mm diameter wire, and I suggested 35 turns as this would work with 3 in hand 1.5 wire at somewhat higher speed. But he reminds me that low winds are his priority, so I would suggest the 40 turns would be better. For that he could use 2x1.7 diameter or 3x1.4 diameter wire.

The payoff with more turns is that it works better in low windspeeds but with the possible downside of stalling as the windspeed rises, especially if the battery voltage is low at the time. Stalling means the turbine gets 'stuck' at a certain low output although the wind is good for a higher output. I have this problem with my AWP at home and I actually put a resistor in series when the battery voltage is low and bypass it with a relay as the voltage rises. The resistor prevents stall and actually gets me more power output in those conditions.

Fewer turns has the advantages that stall is pretty unlikely and that the copper losses are lower, so that for both reasons it will work better in high winds and or at higher battery voltages.

I'd like to be able to offer a recipe that works perfectly in all windspeeds, but to be honest that would require a special controller that changes the turbine voltage. Without such a controller we have to make the best compromise for the anticipated use.

I hope this makes some sort of sense, but don't be afraid to ask me if in doubt about what to do. there are such a lot of things to consider when optimising the design.

all the best,

hugh

Thanks for that Hugh (anyone want some high speed 24v coils) I suppose I could try joining more wire and doing another 5 turns but I would be concerned about the solder joints and heat. So I think I will go for the 1.7 wire and I like the sound of the resistor and relay if I understand it right that would mean I could have a lower power drop say 2-3% from the turbine to the batteries. We are on a slope half way from the top of the hill with a clear view to the south and have sitca forests to the west and east.