I'm trying to come to a non-physicist understanding of the charging of an alternator. I understand all the parts involved. What I don't get is how DC current coming from the diode assembly to the battery's positive terminal can charge the battery. I don't need to understand the electrochemical reactions in general. My question is a logical one and I'm probably off on the logic. For a 12 volt lead-acid battery the negative terminal is at 0 volts and the positive terminal is at 12. The diagram that I have studied shows a pulsed 0 to 12 volt DC current between the diode assembly and the positive terminal and it is this pulsed DC current which supposedly recharges the battery. But if the positive terminal is at 12 volts then this current flow is the same as it would be as if it was coming from the negative terminal (and thus draining the battery).
Perhaps electricity is just not easy to understand. What would work for me is to say that the voltage coming from the diode assembly is actually higher than 12 volts because it is stepped up when the current is induced in the stator. So in this case the current flow would be reversed from the usual flow of the battery. But this is not what I have read so far. There are limited good articles on this and most brush over how this is accomplished or else the technicalities are beyond my understanding. Any help would be appreciated.