Thank you for all your comments. I've never used this site until a couple of days ago so I am a bit green.
The alternator I have built has 48 magnets revolving around 36 coils with laminated metal cores it was originally going to be 48 coils but I didn't have the room. I'm glad I didn't has it is hard enough to turn now. On bench test I only have to move it gently and I have over 12 volts, with a little effort I can light 2 50 watt bulbs. In fact I have made it to efficient. I have built it from nothing so every part had to be made. including the water wheel. Because I sell as a sideline the odd wind turbine, water turbine and solar panel I am often asked from people with a small stream do I have a water turbine that they could use. But the only thing they could use is a water wheel. So this is why I am developing it. The idea is to direct drive it so there are no losses in gearing. So I can assure you all that 12 RPM is the speed that it was doing when I tested it on the water wheel. At the moment I have dismantled the alternator and am trying to improve it. And was thinking if I totally redesigned it and build it like a brake disc alternator would it be more or less efficient. As I have no experience of brake disc alternators I don't no of their efficiency over coils with metal cores. I will add some pics at a later date. Once again thank you for you comments
Please continue in the other thread. Otherwise it gets too hard to track it all. For you and everyone else. Further comments locked on this post to encourage that.
Original Story
http://www.fieldlines.com/story/2007/10/30/18109/338