8 Signs Your Car Battery Is Dying

As the years and miles go by, you may start thinking about the condition of your car’s battery. After all, if it fails, you could be left stranded. While car batteries can sometimes fail with little or no warning, they usually show signs that it’s time for a replacement. Watch for these common signs that your car battery may be dying.

Warning lights

When the battery symbol lights up (typically in red), take this warning seriously. It usually indicates a problem with the charging system, which includes the battery, alternator, and related components. In some cases, a weak battery or charging issue may also trigger other dashboard warnings, such as the Check Engine light.

Slow cranking or “clicking” sounds

Batteries about to fail will often turn the engine over more slowly than usual when you start the car, or they require a longer cranking time. This is a strong signal to have the car’s battery and electrical system tested as soon as possible. Similarly, if you occasionally hear a clicking sound when you turn the key (or press the start button) and the engine doesn’t turn over, requiring you to try again, the battery or its connections may be at fault.

Headlights dim at idle

Driving down the road, your engine should spin the alternator fast enough to supply most of the car’s electrical needs. When you come to a stop, engine speed drops, so the alternator produces less electrical power. At that point, the battery should make up the difference. A weak battery, however, may not be able to do this, so the headlights may dim. You might also notice your power windows moving more slowly.

Battery swollen

If the battery case is swollen, there is definitely a problem. This should prompt immediate replacement and a check of the charging system. (A swollen battery may not look perfectly rectangular; the sides might bulge outward, the top may appear raised or puffed up, or the case may look slightly warped or uneven.) Swelling can be caused by overcharging or exposure to extreme temperatures.

Battery leaking

Leakage is a major issue because the liquid inside the battery is acidic. It can burn skin, damage clothing, and harm paint and electrical connections. If a battery is leaking, you’ll usually see signs on or around the battery itself—typically in the engine bay or trunk, depending on where the battery is located in the vehicle. Look for wet or damp areas on the battery case or liquid pooling on the battery tray underneath it. Leakage can also lead to corrosion on the battery’s terminals, which appears as a white, powdery buildup that may have a blue or green tint.

Frequent jump starts needed

If your car sits for a day or two and then needs a jump start, it’s time to check the battery and electrical system. Modern cars do draw some power even when parked, so needing a jump after a long period of inactivity (two weeks to a month or more) isn’t unusual, but it should not happen frequently.

Rotten egg smell

If the battery emits a rotten egg odor, there is a problem. Most likely, battery replacement is in your near future.

Old age

How long should a battery last? While three to five years is often cited as the norm, factors such as high heat (which can actually be more damaging than extreme cold), excessive vibration, and repeated deep discharges can significantly shorten a battery’s lifespan.

Battery shopping tips

When replacing a battery, follow these guidelines:

• Choose one that meets or exceeds the ratings of the battery that came in the car when it was new.
• Pay attention to the cold cranking amps (CCA) rating and the ampere-hours (Ah) specification.
• Make sure the CCA rating is based on testing at 0°F (-17.8°C), not at warmer reference temperatures.
• Most cars use wet-cell lead-acid batteries, but some vehicles are equipped with AGM (absorbent glass mat) batteries, which have a longer life expectancy. If your car came with an AGM battery, replace it with another AGM battery; do not downgrade to a standard flooded battery.
• Ask for the manufacture date; avoid batteries that have been sitting on the shelf for a long time.
• Check the warranty length as a rough indicator of expected quality and longevity.

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Your car battery rarely dies without warning. Spotting the signs early can help you avoid a dead battery, a stressful breakdown, and getting stranded on the side of the road.