Hello everybody,
I'm posting this after carefully reading for about 3 weeks the board (the old one too) in search of a complete answer. My findings ended up in only bits and pieces of information on this matter. I want to build a axial flux generator but it seems that the closest I can get to Neodynium magnets are HDD drives. So I got closer and after many trips to local computer shops I managed to get 81 magnets. The quest was long and tidious, in some places having to convince people that i'm not a freek building some illegal instalations (they get suspicious when someone needs so much high-tech garbage) but some of them were patient enough to find why I need them. Some even wished me luck.
But it seems to me I need more than that since I couldn't find any plans on this matter yet. Some people tried different setups with HDD magnets but there's only bits of info's out here. I may have to make them myself and that would be fine with me but when you deal with questions like how many magnets, what kind of placement, how many coils and how many windigs things get complicated.
After all this reading I would try to build a dual rotor axial flux generator. Here comes the questions ... How many magnets should I use? I'm thinking of 12. How many poles? Well, since I gathered them so hard and they are so many sizes/thicknesses/shapes I don't feel comfortable breaking them in half. Or maybe I should, i'm not sure yet. 24 poles with the magnets lined along the circumference sounds good to me. A dual rotor with 12 magnets, 24 poles, 3-stacked should be fine. The problem is that the magnets have different shapes & thicknesses. I could use them wisely to match the total magnets height but will the smaller ones cause any field loss?
As for coils I think I'll go with 9. Is this OK? There will be 24 poles ...
The shape of the coil would be round but I'd rather make them larger (longer legs). That's another matter I need expert advice at. As well as the number of windings. Of course I'll make a test coil first and post the results out on this board for further debates.
My aim is to charge a 12V battery to run some 12 V lights and a small inverter for a couple hours a day. It shouldn't be more than 150W load I presume. All this should be done at low wind speed. The average windspeed here is around 12 mph.
I try to keep my expectations low here.
Since I'll order my rotor/bearings/etc to be made in a factory out here, I will need exact plans on the whole thing. Plans I'll have to make by looking at the pictures posted on this board. There has to be a better source... Can anybody help?
My main concern is the low magnetic flux due to smaller magnets, coil shape and rotor/bearing/furling related mechanics. Unfortunately, Hugh Piggott's book is out of reach here in Romania. I have to say I always liked to build things but that doesn't mean I got to welding or anywhere near a lathe. On top of that, everything's metric here so wish me luck, I think I'll need it.
Thanks,
Claude