Alternator wired wrong ??

Any of you following my build thread knows my first start up was a success except for the restored alternator not charging. I sent it out to be tested and it tested fine. The guy says one of the small studs should have power to it to "excite" the alternator but I dont see a wire in the harness that goes there, so what am i missing ?
I guess this should be in the tech section.... oops

 

here are a few pics i took of my wiring before my build, hope this helps.

 

Original pic shows the two small wires on the other small stud from where you have them now. Some Motorola's had the diode trio going to only one small stud so it did make a diff.

 

Unlike generators which use permanent magnets to create a field, alternators use a dc voltage coming through a regulator to a coil inside the alternator (kind of like an electromagnet) for excitation. The greater the load imposed on the alternator, the higher the excitation voltage goes to build a stronger magnetic field to accommodate the load, up to a point. You can reach saturation if you load the alternator beyond its rated output, and then weird things happen. Do you have an external regulator? If so, those wires, or that wire, should be connected to the small post in most cases. I have seen other wiring schemes, but this is usually the way these are set up. I took another look at your alternator and I agree with Walt. Your wiring is incorrect on the small posts, but I hope the explanation above helps you understand how an alternator works as opposed to a generator

 

Why does mine have two power leads to the big stud ?

 

John, this site has answered a lot of my questions, read the electrical section, tells all about the wiring you are looking for, hope this helps you.

http://www.myedocs.com/onlinefiles/Jeep/Manuals/53-71 Jeep CJ & DJ SM.pdf

 

The large stud is connected to your battery. This allows the alternator to charge your battery as this is the output stud. However, you have several other things in your Jeep that need to be powered. Sometimes these loads are connected to the same wiring at the battery terminal, and sometimes they are connected at the alternator, or both. Since loads can be connected anywhere along this circuit, since it is the same point electrically, they are generally connected wherever it is most convenient. When this is done, however, usually there is an in-line fuse assembly of some kind or another placed in the circuit. The most common way to feed the fuse block assembly is to come off the alternator or battery post, go through a fuse assembly (in-line fusible link) or a main fuse on the fuse block and then the circuit splits to feed other fuses which supply power to all the loads in the vehicle. Hopes this helps...

 

Just an FYI the reason the alternator wasn't charging was that the amp light had no power. Once hooked up to the B on ignition switch it started charging. Around 14.5 volts at idle

 

That will do it every time. That is why it is designed to turn on the charge light when you turn the key on before start.