When you shut the ignition off, and the relay opens, you are breaking the circuit from the alternator to the battery. As BobM advised you the other day, that is NEVER a good idea. One day, when the alternator is charging heavily to recharge a low battery, and you do that, the resulting voltage surge will "kill" the internal regulator, and/or the rectifier, and/or the diode trio. Why make it so difficult? BobM, with his diagrams, has shown how to wire up a STANDARD 10SI alternator, which is typically even less costly than the goofy one-wire units. The standard 3-wire alternators will begin charging at a low speed, and will not drain the battery, as some one-wire units do. A standard alternator, and a diode are CHEAP to buy, and are simple to connect, and use. WHY do you guys persist with the troublesome one-wire units???? All you need is the alternator, some simple connections, and a diode (1N5008) in the lead from the #1 "switched excite" terminal to the ignition swith. (If desired, a # 194 lamp will work equally well in place of the diode... Use a dash-mounted "idiot light", or simply mount a side marker light out of sight.) 
That's it, a diode for about a buck, and no need for a $$ relay, and heavy wire and terminals to connect the relay up.
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