Wiring Trispark regulator on 750 GT

[Chasbmw]

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

[Craig in France]

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

[Chasbmw]

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

[Craig in France]

<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 ...

[Chasbmw]

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

[Chasbmw]

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,