I'm modding a Nerf gun (Rapidstrike to be exact), and I put a 3S Lipo in there with 1000 mAh. The circuit right now is a rev switch, trigger switch, switch behind the pusher, battery, pusher motors, and flywheel motors. The switches are 21 amp switches and the motors are all 12V motors. I want to put an LED strip in the blaster, however the LED strip is assumed to be rated at 4.5V (I ripped it out of a Harbor Freight light and it took 3 1.5V batteries. There were no resistors inside the light.), and I'm unsure how I can include the strip in the circuit safely. I assumed I could put a resistor in there, however I didn't really know how to calculate what kind of resistance I needed. I'm familiar with Ohm's law, however I have no idea how I'd calculate the current to be able to get the resistance. In addition, I assumed I could just throw a resistor in by the LED strip, but I'm not sure if this is the proper way to do it. I have an image of how I assumed it might work, but please correct me if I'm wrong:
If this is correct, how much resistance would I need? If not, how can I wire it properly? I have very little electrical engineering experience, so I figured I'd ask the experts here for guidance.