I have created a circuit. The batteries are in series, and the igniters for my rocket are in parallel. There are three igniters. When I check the voltage that will be going through the various igniters, the voltage appears to fluctuate. It goes from 0 volts to 2.5 volts to 6 volts to 18 volts. On other places where the igniters will be placed, the voltage will just stay at its correct voltage which is 18 volts. When I test fire this circuit and place the igniters into their places, the igniters ignite at different times. How can i get them to ignite at the same time? They have to ignite at the same time. I think the possible reason for this is that the batteries are in series. Do the batteries have to be in parallel?