Battery & Alternator

Why it matters

The battery stores the power to crank the engine and to run electronics when the alternator cannot keep up. The alternator recharges it while you drive. A battery typically lasts three to five years, and heat shortens that. A failing alternator will drain a healthy battery, so replacing the battery alone just delays the problem.

Signs it is time

• Slow crank, especially on cold mornings
• Dim headlights at idle that brighten when you rev the engine
• Battery or charging warning light on the dash
• Battery is four or more years old, or the terminals are crusty
• A clicking sound instead of the engine turning over

If you wait

You will find out in a parking lot at the worst possible time. Driving on a failing alternator can also leave you stranded after dark with no lights, and repeated deep discharges shorten the life of every electrical component in the car.