A flashlight of the old fashion kind is basically a battery case with a switch and an bulb on one end. This will be my model for my case, a cylinder with the cells stacked one on top of the other.
This is not a new idea, and many people look for a piece of pipe or similar material for the case, just the right size can be hard to find, and the walls are often so thick that the case is bulky. Here we will make our own tube using the clear plastic from a soda bottle.
A few other elements are required for a complete case:
- caps for the ends to hold the batteries in.
- contacts and leads
- some sort of spring assembly to keep the cells in close electrical contact