Final answer:
The statement is true; a test battery, referring to battery testers, measures various indicators of a battery's health, such as internal resistance, by using a load resistor to test the terminal voltage under a load.
Step-by-step explanation:
The statement, "A test battery is based on a combination of several tests that can then measure an array of predictors," is true. A test battery, in the context of the passage which discusses battery testers, refers to a device or series of tests designed to assess various aspects of a battery's health. For example, battery testers like those shown in Figure 21.13 and Figure 21.15 utilize a load resistor to intentionally draw current to gauge if the terminal voltage falls below an acceptable threshold. This kind of testing effectively measures the internal resistance of the battery, which in turn indicates the battery's condition. If the internal resistance is high, it implies that the battery has weakened, as shown by a lower terminal voltage. Similarly, a take-home experiment with flashlight batteries can reveal the functional differences between new and old batteries.