part 2. Sorry guys... Ive checked literally everything. The question I have is what tells the voltage regulator that it needs to put more or less power out?

thanks in advance

 

"Power" is actually determined by the electrical draw from the system and the battery's state of charge. The output voltage is regulated by the regulator and it determines when voltage is too high. It can't increase voltage-it can only reduce it. Regulating, in this case, is basically preventing voltage from going too high.