Sandwich, the line-following robot, uses a 9 V battery for power. In fact, most of my robots use 9 V batteries because the batteries are so small and lightweight. In this chapter, you're going to learn how to test a 9 V battery (see Figure 7-1) and find out about the differences in battery brands and chemistries.
Figure 7.1. Alkaline 9 V battery
How many volts in a nine-volt battery? Yes, it's sort of a trick question. Although the answer is somewhere around nine volts, the actual voltage varies based on what the battery is made of and how much of the battery's power has been used up.
During this stage, it's not necessary ...