Turn off the car and all accessories
Inspect the battery case for cracks, leaks, or swelling
Check the terminals for corrosion or loose connections
Use a multimeter set to DC volts
Place the red probe on the positive terminal
Place the black probe on the negative terminal
Read the voltage
Compare the reading to a fully charged battery
Test the battery with the engine off
Start the engine and test the voltage again
Check for charging system voltage
Use a battery load tester if available
Follow the load tester instructions
Observe whether the battery voltage drops too low under load
Check the battery age and service history
Have the battery tested at an auto parts store if needed