How do you change and measure batteries?

To change a battery, first ensure the device is powered off, then locate the battery compartment, which may require a screwdriver or a simple slide mechanism. Remove the old battery, noting its orientation, and insert the new battery in the same position. To measure a battery's voltage, use a multimeter set to the appropriate DC voltage range, connecting the red probe to the positive terminal and the black probe to the negative terminal. A reading close to the battery's rated voltage indicates it is functioning well, while a significantly lower reading suggests it may need replacement.