Perform a load test with alkaline batteries for the most accurate result. A load test measures the battery's power when it's in use. Higher-end multimeters have 2 load settings, 1.5V and 9V. For a AA, AAA, C, or D battery, set the voltage dial to 1.5V. Set the voltage to 9V for a 9v battery. Hold the black probe to the negative end of the battery and the red probe to the positive end to test the battery's milliamps.^[9]

• A fresh 1.5V battery will read 4 milliamps, and a fresh 9V measures 25. A 3.6v battery should read around 8 milliamps.  Readings below this indicate a dead battery. At 1.2-1.3V is typically when most 1.5V batteries start to become weak.
• This particular test won't work on a lithium ion battery because multimeters don't have load test settings for their voltages.
• Add a multiturn potentiomenter, decade resistor box, or rheostat in parallel with the battery for to dial in your exact load. Be aware of not overloading your device you are putting in parallel.