Turn off the car and remove the key
Open the hood and locate the battery
Check the battery case for cracks, leaks, or swelling
Inspect the terminals for corrosion or loose connections
Make sure the battery cables are secure
Check the battery age on the label
Use a multimeter to test voltage
Read about 12.6 volts or higher for a fully charged battery
Read about 12.4 volts for a partially charged battery
Read below 12.2 volts for a weak battery
Test voltage while starting the engine
Check for a drop below 9.6 volts during cranking
Have the battery load-tested if needed
Check for dim headlights or slow engine cranking
Replace the battery if it fails testing or shows damage