Doubt about red wire coming out of the alternator

[VELOCIRAPTOR]

I'm new to this forum, so I introduce myself and thank everyone for the help that I'm sure you can give me. I am writing to you from Madrid and I recently purchased a Morini 350 from 1977 that I am restoring. Surely I will have many doubts and I hope that with your help I can solve them.
The first of them is as follows: Two yellow cables come out of the alternator that go to the rectifier, a green one that goes up to the coils that feed the spark plugs and a fourth red cable that apparently, without going through the rectifier, feeds the battery.
I have very little knowledge of electricity, but I think that to charge a battery the current has to be continuous and not alternating, so I don't understand how this red cable, which I understand carries alternating current, can charge the battery.
Sorry if the wording of the message is not good. I don't know much English and I used Google translate.
Greetings to all.

[morini_tom]

The red wire is a 12V positive DC feed from the battery to the alternator centre tap. It does not carry AC from the alternator.

The yellow wires are AC which go to the regulator and from there a brown wire connects to the fusebox. So charging is via the yellow and brown wires, not the red.

The green wire is as you say the feed to the transducers ('coils'). An important note here- Never EVER put 12 volts onto the green wire. You will kill the transducers.

[norbert]

But what is the reason for tis cable, feeding the alternator with 12V? Am I right to suspect, that you can take it of without consequences for charging the batery?

[Daddy Dom]

¡Hola y bienvenido!

Estuve en Madrid en enero, es una ciudad preciosa.
DD

[BumbleBee]

I think it's like this...
Imagine two sets of alternator windings. Both have red wire on the top and yellow wire on the bottom. Generating electricity separately. The regulator rectifier unit is in the "yellow side" of the circuit to make DC for the battery and other DC circuits on the bike. Now join both reds together where they meet the windings, so now you only need one red wire. The alternator output comes from those three wires (two yellow and one red). You have two sets of alternator windings making electricity in parallel.

[tigerbillsbikes]

Just curious. Will the engine start with a dead battery or is there a certain amount of voltage needed to operate the electronic ignition?

[Ming]

On a standard system, ignition is separate from power, you can run without battery and lights. But, a flat battery will stop the regulator from working as it needs a reference voltage.

[tigerbillsbikes]

My alternator is not charging and therefore the battery is very low. Will that affect the running or better yet ignition function?

[Ming]

Er - if your battery is low, regulator will not work. Ignition is not connected to the battery, as I said. Or do you have a modified system ?

[tigerbillsbikes]

It's a stock system. I'm new to Morini's and wanted to find out if the bike will still run with a dead battery. For instance, a Boyer on a Norton has to have a certain amount of battery voltage before it will start. Then again Bultaco's have a ignition coil on their stator (like a Morini) and as we know they are designed to run without a battery. Two examples and of course there are many others. I was wondering if a low or dead battery in a Morini affects the strength of the ignition. Therefore, should the charging system be weak or completely defective and causing a low or dead battery will the bike (Morini) still run normally?

[Ming]

Perhaps ”yes, it will still run as normal” is more comprehensible.

[MickeyMoto]

The ignition system is self contained. No battery required. Four components. Magneto coil, two transducers and the bit on the end of the camshaft for ignition timing. All good, until one of the components breaks down.

[tigerbillsbikes]

That answers my question. Thanks!

[Ming]

Ah, perhaps I was typing with a French accent?

[MickeyMoto]

Mais oui, monsieur. Mon dieu, Mon dieu!