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I have a 750 GT with a new 200w three wire alternator (2x yellow, 1x red). I want to use a Trispark MOSFET regulator, Trispark say that I should ignore the red wire from the alternator and just connect the 2 yellow wires to the regulator.

What is the purpose of the red wire? I see it being connected to the + lead at the battery, before the ignition switch?

Any views from people who know more about the magic of Ducati electrics

Charles

Hmmm.

As I understand it, because the AC power outputs of the original two and three wire alternators are not the same, they require different regulator-rectifiers.

Or, to be strictly accurate, it's actually the other way round: the early reg-recs do the rectification in a different way to the later ones - half wave vs. full wave. This means the outputs and the wiring of the two alternators are correspondingly different.

Or at least they used to. But I can't say whether this still holds true for modern replacement items such as yours. However, here's a wiring diagram that you might like to show Trispark. It comes from the 860 workshop manual and illustrates the differences in the reg/rec associated with the change over from the three wire alternator to the two wire alternator.

HTH

Craig

Thanks for reply Craig……..

Looking at the diagrams it seems as if on the original regulator, the connector to the red wire is simply a pass through to the + terminal of the battery and doesn’t actually do anything within the regulator itself. As you say, worth a conversation with TRi Spark

Chasbmw wrote: ↑Fri Mar 10, 2023 4:01 am <sniP> Looking at the diagrams it seems as if on the original regulator, the connector to the red wire is simply a pass through to the + terminal of the battery and doesn’t actually do anything within the regulator itself.

Correct.

When using a modern reg/rec, you may have to isolate this cable. But best not to take my advice, but refer to the manufacturer instead ...

I’ve sent an email to Tri Spark with your copy of the wiring diagrams, so interested to see what response I get

Cheers Charles

Not much help from Trispark, this was their response, at least I now know that the alternator is called a split phase winding with a centre tap!
The charge control light is not an issue for me as it will be handled by a Monsoon charge indicator LED.

Hello Charles,

Thanks for your email. Your bike has a 3 wire alternator but as you said it is not 3 phase. I believe it's called a split phase winding and has a centre tap.

I think you should consult with an electrician with some experience installing the type of alternator with a conventional regulator like ours.

The other thing to consider is the warning Light control in the original regulator is not catered for in ours.

hope that helps,