Slow engine cranking
Clicking sound when turning the key
Dashboard lights dimming
Headlights appearing weak or flickering
Electrical accessories working poorly
Battery warning light on the dashboard
Needing frequent jump-starts
Engine starting inconsistently
Corroded or swollen battery case
Rotten egg smell near the battery
Battery age of 3 to 5 years or more
Low battery voltage reading
Terminals showing heavy corrosion
Car struggling more in cold weather