Owning and understanding the workings of a multimeter can quickly pay for itself. The average household uses dozens of batteries to power all sorts of devices, and batteries are not cheap. You may be throwing money in the rubbish bin by discarding still usable batteries, whereas multimeter owners are able to run a simple multimeter battery test to salvage usable batteries and thereby lower their shopping bills.
Set the multimeter to the direct current (DC) setting, and the scale to 12 volts (V).
Touch the red probe to the little round button on top of the battery marked with a plus sign.
Press the black probe against flat metal underside of the battery.
Read the multimeter scale. If the reading is 10 per cent below the battery’s rating, discard the battery. Dry batteries have an output rating of either 1.5 V or 9 V. If the reading is below 1.35 V or 8.1 V respectively, the battery has no more useful life and should be replaced.
Do not change the multimeter settings or turn the dial when the multimeter is connected to a live circuit