Step 4 · Perform Voltage Test
Connect a digital multimeter to the battery terminals. Set the multimeter to DC voltage mode (usually indicated by 'V--' or 'DCV'). Place the red probe on the positive (+) terminal and the black probe on the negative (-) terminal. Read the voltage displayed on the multimeter. A fully charged battery should read around 12.6 volts or higher. Readings below 12.4 volts indicate a discharged battery, and below 12.0 volts suggest it might be failing.