Engine cranks slowly or not at all
Jump-start works, but the car dies soon after
Battery warning light is on
Headlights dim at idle but brighten when revving
Electrical accessories act weak or intermittent
Battery is old, swollen, leaking, or corroded
Battery voltage is low with engine off
Battery voltage does not rise with engine running
Car starts after charging the battery, then fails again
Clicking sound when turning the key
Repeated dead battery after driving
Alternator belt is loose, worn, or broken
Burning smell from alternator area
Whining or grinding noise from alternator
Multimeter shows about 12.6V engine off and 13.7V to 14.7V running
Multimeter shows under 13.5V with engine running
Multimeter shows over 15V with engine running