So after a few fits and starts, I've finally gotten a bicycle powered alternator built, using an old alternator from a car. One wouldn't think that the wiring would be that difficult but, after every wiring configuration that I can logically concieve of, it still doesn't produce power. Below are a few pictures of the design.
Now I know that the two smaller wiring tabs are the connections for the field current to the rotor coil, and the sampling current. The large post is the output that runs back to the battery for charging. The way I was trying to wire it, there's a 14g wire from the + terminal on my marine/RV battery to the field current tab, and a 4g wire from the output post on the alternator back to the positive terminal on the battery.
For starters, I've read elsewhere on the web that, when current is supplied to the rotor coil, the outside casing on the alternator should produce a magnetic field strong enough to stick small pieces of metal to, like screws or paperclips for instance. None of the alternators I've been able to get for free have done this. Does this rule of thumb hold true to your knowledge or is it some BS Wive's Tale??
I also wonder if supplying current to the "sampling current" tab is necessary for the alternator to produce power. In vehicle alternators, the sample current tells the regulator how much voltage is in the battery so it knows when to increase or decrease current to the rotor coil to keep the battery between 12-14 volts. I figured if there was no current supplied to that tab, the internal regulator would always read a sample current of zero and thus, be fooled into sending the maximum amount of voltage to the rotor coil (14V?).
Another question I had was whether or not some sort of ground is required to close the circuit. One thing I tried was running a wire from one of the mounts to the neg. terminal on the battery. Is this even necessary? I haven't heard about any of these homebrewed alternators having a ground wire involved.
I've tried everything I can think of to get these alternators to work and the only thing I can think of being the problem is that I have three dead alternators in my possession. They all came from automechanics that didn't know if they worked or not. Nevertheless, once I get ahold of an alternator that I KNOW actually works, it would help to have all of these questions already answered so I don't have to waste all of that time experimenting and risking getting zapped!
Thanks for any and all useful input you may have.
Getting a bit large on file size on those photos. I will leave it this time but please read the info on resizing photos for more friendly download. Lots of our users are on slow connections. Also resectioned to a more appropriate section.