Signs Your Car Battery Is Dying
3 lessons in this series, 6 min in total
- Signs Your Car Battery Is Dying 2 min read
- How to Test a Car Battery With a Multimeter 2 min read
- Should You Charge or Replace a Weak Car Battery? 2 min read
Sources: AAA’s battery guide, AAA Club Alliance’s winter article, Interstate Batteries’ FAQ and battery-test article, and Yuasa. More on how we research.
The six warning signs
| Sign | What it can mean | Check first | Source |
|---|---|---|---|
| Slow crank, a short pause at startup or slow cold starts | Losing power; warm weather can hide early weakness | Resting voltage | AAA, Interstate |
| Clicking when you turn the key | Possibly a bad connection | Tight cables, clean terminals | AAA |
| Dim incandescent headlights at idle, slow windows or lost Bluetooth | Battery may not support the electronics | Resting voltage | AAA, Interstate |
| Battery or charging warning light | Battery or charging system trouble | Voltage with the engine running | AAA |
| Frequent jump-starts | The battery is struggling | Resting voltage, then a shop test | AAA |
| Bulging case, sulfur smell, stains or corrosion | Possible damage; bulging often means overcharging or overheating | Cracks or leaks | AAA, AAA Club Alliance |
The warning light can also point to the alternator; an engine-running reading helps tell the two apart. A swollen, cracked or leaking battery is a stop sign: read when not to jump-start a battery first.
How old is your battery?
AAA’s general rule is to replace a car battery every three to five years. It says batteries may last five years or longer in cooler northern climates, but about three years is more typical in the South. Heat speeds up wear, and AAA notes that under-hood temperatures can top 200°F (93°C).
AAA says to test the battery every year once it turns three. Interstate suggests at least twice a year, before the summer heat and before the winter freeze.
Our rule: if the battery is three or more years old and shows any one of the signs above, test it now, before winter.
Why a weak battery shows up in cold weather
AAA Club Alliance says a car battery loses about a third of its power in freezing weather and has only about half its power at 0°F (-18°C) or below. Thick, cold oil also makes the engine harder to turn over.
Cold cranking amps (CCA) rate starting current in the cold; see what cold cranking amps measure. Interstate’s example: a new 500 CCA battery might test at 600 CCA or more at 70°F (21°C), while a worn-out one could fail at 40°F (4°C) and a badly weakened one at 60°F (16°C).
A discharged battery also freezes sooner: at 15°F (-9°C) per Interstate’s FAQ, or 27°F (-3°C) per Yuasa, so figures differ by source. More in will a car battery die sitting all winter. For a car parked two weeks or more in winter, AAA Club Alliance suggests a tender to keep a stored battery charged.
If any sign fits, check resting voltage with a multimeter to confirm it.
