
For those doing the assessment at home, the process is straightforward. After you've made sure that everything is turned off, including the cabin lights, connect the red/positive test lead to the battery's positive terminal. Then, connect the black/negative test lead to the corresponding terminal on the battery.
You'll soon see a reading on your voltmeter. The target range is anything above 12.4 volts. Being below that level means your battery will likely have trouble accepting and/or holding a charge. Replacing it would be a smart move at this point.