Batteries provide the needed power to use many of the portable devices that we own. Sometimes, you need to know how much juice is left in the cell before it runs out. Here is a way to use a digital multimeter in order to determine the life of a battery.
Collect the battery or batteries you wish to test. These can be out of your devices, or you have a drawer full of them and you need to identify the live ones.
Note the batteries voltage. For AA, AAA, C, D, this is 1.5V. For 9V, it is, surprisingly, 9V.
Set the digital multimeter to measure voltage. You want to measure DC voltage, and the maximum will be the battery's rated voltage.
Measure the battery's voltage. If the voltage matches its rating, it is a live battery. If it is slightly less, then you are looking at a used, but still usable battery. If the voltage is smaller than 2/3, such as 1V for a 1.5V battery, then it is likely not to work.
If you use used batteries that still have life in them, try to get more around the same charge level. You always want to use like charge levels in your batteries.