Not sure about your smoke alarm battery? Wondering about the mystery batteries in your kitchen drawer? Check them with a multitester to find out instantly if they still have juice.
Set the voltage selector to the 1.5V setting (1.5 volts) and touch the red probe to the (+) end (with the nub) and the black probe to the (-) end of 1.5-volt batteries.
Read the battery test scale. Red is bad and green is good. This battery is bad.
Set the voltage selector to the 9V setting (9 volts) and touch the red probe to the smaller (+) connector and the black probe to the larger (-) connector (as marked on the battery label).
The indicator is in the green area, which means this battery is still good.
Multitesters have many uses, and one of the handiest is testing common household batteries. A weak or dead smoke alarm battery in a fire, or a dim flashlight bulb during a blackout, can be downright dangerous. Pull out that multitester and check those vital batteries so they're ready when you need them.
Insert the black probe into the (-) terminal, and the red probe into the (+) terminal. Rotate the voltage selector switch until it points to the voltage you're testing, and then test batteries as shown in Photos 1 and 2.