Have just been given one of these - found lying in the back of the shed at the yard. It’s cleaned up nicely, and seems to work - however, it is missing the turntable (probably still in the shed somewhere), but I think I can get round that if I can’t find the original. However, talking to our fitter, he said that it needs some unit on the back of the alternator so it can only be used when the engine is running, but he didn’t know exactly what it was. I’m assuming that it’s just a high power relay, triggered from the D+ terminal of the alternator, so it’s only energised when the alternator is pumping out current (Same as a split charge relay in a car / caravan). Does this sound about right?
Gary