The main idea is to control Repellers through Arduino, so current should be given to Repellers only when Arduino checks for some situation to be true. I would love to save the power and make my devices use less power wherever necessary.
As for using repellers in parallel or serial, i actually wrote there are two repellers in this arrangements, thats why i used 6+6, its nothing to do with serial and parallel. I am actually interested in knowing what kind of power will be ideal for this arrangement where 2 different repellers are connected to Arduino device?