So we are off grid and have a 24v system and right now we're strictly solar. We're wanting to add a wind turbine so we have power on a cloudy day but I'm having trouble finding permanent magnet dc motors that have a high enough voltage to rpm ratio to give me 24v at a normal wind speed. Is there any way to get around this? I found this diy article (attached) but it doesn't explain enough for me to know exactly how to build it. If anyone has any ideas on what I could use to get 24v at around 400 rpm or could explain better how to do the steps in the article (for someone who only knows a little bit about electrical stuff) I would really appreciate it!
I bought a book years ago for like $50 called "Homebrew wind power", which details all the steps to making your own turbine. I think they run the website otherpower.net or something as well. I skimmed through the book briefly when I got it, but have been waiting until I moved out to my property to start work on it. So I'm not an expert on the subject.
While you're building your alternator, I believe it's the size of your copper wire and the amount of times that you coil the wire that determines the voltage. As long as you or someone near you is able to cut and weld metal, work with fiberglass resin, and carve the blades, you can build a turbine based around your needs. The book is also pretty good about explaining theory behind all of the steps they take when building.
A 7' diameter turbine from their book will generate around 275 watts at 400 rpm.
I have used a stepper motor for the generator and get 24 volts with a good wind. This motor has 2 phase AC output so it needs a rectifier to convert it to DC. I am using 14" blades.
You could also try a 90 VDC servo motor which may be easier for you to find. Old treadmills use this motor. The trick is to match it to a set of blades to give you the output you want.
As per my experience while you have to build your alternator, it's the size of your copper wire and the amount of times that you coil the wire that determines the voltage. As long as you or someone near you is able to cut and weld metal, work with fiberglass resin, and carve the blades, you can build a turbine based around your needs.