How to Test a Battery with a Multimeter

Measure voltage, judge capacity and avoid the classic false readings.

Set the multimeter to DC volts 20V range. Red probe to positive terminal, black to negative, read the value: a fresh AA reads about 1.6V, a 3V coin cell about 3.2V right out of the pack.

An unloaded reading can look healthy while the cell is dead under load. For a real check, measure with the device on, or use a battery tester with a load resistor.

For coin cells, test between the two flat faces; corroded or white-coated cells should be replaced — the coating is often the failure point, not the chemistry.