XS400 SE (4G5) Project

[tstidham]

Because it operates like an old style alternator with a field coil to excite the process. I don't know how mechanically adept you are or your age, but back on the day on older cars, sometimes when you first started the car, the BAT light would be on because the alternator wasn't turning fast enough to generate enough voltage. Those alternators were wired for self exciting the field coil. So you would rev the engine to make the light go out and then all was good.

 

[Bulisti]

I do understand that. But what I don’t understand is how power is coming through even though the field coil wires aren’t connected. Logically, there shouldn’t be any current then. So the field coil isn’t in operation since its wires aren’t connected anywhere, and yet I’m still getting normal voltage on the three yellow wires — about 20V at idle and easily 50–60V at higher revs.

 

[CaptChrome]

how power is coming through even though the field coil wires aren’t connected

Probably because the rotor that the field coil is part of has some residual magnetism even though there is no current in the field winding. Just like if you take a steel or iron rod (like a nail), wrap a coil of wire around it and connect the wire to a battery, the rod will become magnetized. The magnetic field of the rod will not be as strong as when the battery is connected, but it will be magnetic.

 

[Bulisti]

How long does that magnetization last? I mean, several hundred kilometers have been driven without the field winding wires connected, and it still gives normal readings from the yellow wires

 

[Bulisti]

Let’s bump this thread up a bit since I’ve finally received the part I ordered. So, I ordered the voltage regulator from this link: https://www.ebay.com/itm/364615115887. Now I’ve started installing it, but the connectors are different (because the previous owner had tried a different type of voltage regulator).


There are 7 wires coming from the stator: 3 white ones (which are for the coils), 1 yellow, 1 blue, 1 green, and 1 brown. I got wiring instructions from the seller (see the attached image).


Electrical wiring isn’t really my strong suit, so I’d appreciate some help. The three white wires will of course go to the white wires on the regulator. The green goes to the field coil, the red to the battery – but should I connect the regulator’s ground wire directly to the chassis/battery negative, or to the brown wire coming from the stator? Also, where should the yellow and blue wires from the stator be connected?

 

[Revvy Kevvy]

Hey Bulisti, I am next door to you in Sweden near Gavle, if you and I get these things working next summer you wanna meet up for a road tour?