In order to reduce the size and stiffness and number of wires that are needed to wind each coil, I prefer to connect the coils of a 12-volt stator in parallel rather than in series. This means each coil has more turns of thinner wire to achieve the correct voltage at the desired speed.
We could simply connect all of the coils in each phase together in parallel, but the reality is that they will produce a slightly different output signal (in voltage and in phase/timing) which would lead to some parasitic currents between the coils.
For this reason I prefer to rectify each coil separately. The rectifier diodes block any mutual currents. Connect in parallel the outputs of all the rectifiers, using DC buses, positive and negative, which conduct the current to the battery.
I start by connecting all of the ‘starts’ of each of the coils together using a ring of wire. This ring can also be made tight enough to hold the coils in position against the island in the stator mould.
Next I connect a tail of flexible wire to the finish of each coil and lead it out to the rectifier box. The rectifiers are usually single phase because they are cheaper to buy. But it does not matter at all which wire goes to which rectifier unit. Each coil finish just has to be connected to the AC terminal of one of the rectifiers.