CAR WON’T START WHEN IT’S COLD?
The first freeze comes, you turn the key, and the engine groans or just clicks. Cold weather is hard on car batteries, and it often exposes one that was already weak. Here are the signs, how to tell a battery problem from the alternator or starter, and what to do before you are stuck.
📞 Call to Get Your Battery TestedA car battery that works all summer can quit on the first cold morning. The battery did not suddenly break; the cold simply asks more of it. Here is what is going on, and how to read the clues your car gives you.
Most car batteries last about 3 to 5 years, and cold weather can push a weak one over the edge. A slow, labored crank, dim lights, or a clicking sound are common warning signs. If the car jump-starts but won't restart later, the battery is the likely culprit. If it dies soon after a jump, suspect the alternator.
WHY COLD WEATHER HURTS BATTERIES
Cold makes the chemical reaction inside a battery sluggish, so it produces less power just when the engine needs more. Engine oil also gets thicker in the cold, which makes the engine harder to turn over. AAA's Dan Cave has been quoted saying a battery loses about 35% of its power at 32°F and about 60% at 0°F. Those are rough figures, but they show why an old battery fails first.
7 SIGNS YOUR BATTERY IS GETTING WEAK
- Slow crank. The engine turns over lazily, or takes several tries to start.
- Dim lights. Headlights, dashboard or interior lights look weak, or the radio will not come on.
- Slow windows and wipers. Power accessories move slower than normal.
- Clicking, or nothing at all. You turn the key and hear a click or silence.
- Battery warning light. Firestone notes this light usually points to a charging system problem, not just the battery itself.
- Corrosion on the terminals. A crusty buildup on the posts, or loose cable connections.
- A swollen or misshapen case, or a leak. Firestone says a swollen case indicates internal damage and usually the end of the battery's life.
Do not ignore the early signs. A weak battery can leave you stranded the next time you shut the car off. Getting it tested before it fails is easier than a dead car in a parking lot at 6 a.m.
BATTERY, ALTERNATOR OR STARTER?
A car that won't start has three usual suspects. Here is how the clues line up, based on guidance from Les Schwab:
| What you notice | Likely cause | Next step |
|---|---|---|
| Slow crank, dim lights, or silence. Jump-start works, but it won't restart later | Weak or dead battery | Have the battery tested |
| Car starts, then stalls. Or dies soon after a jump. Lights dim and brighten, or the battery light is on | Alternator (charging system) | Have the charging system tested |
| Engine will not crank at all, but the lights stay bright | Starter or another part | Have it diagnosed |
These are clues, not a diagnosis. A bad alternator can also drain a good battery, which is why a test is better than guessing.
WHAT TO DO THIS WEEK
- Note the age. If the battery is more than three years old, or you do not know when it was replaced, get it tested before it gets colder. Lescaille Car Care tests batteries, and walk-ins are welcome. Ask what the test includes.
- Look at the terminals. Corrosion or loose cables can cause starting trouble even when the battery is fine.
- Take a longer drive once in a while. Frequent short trips may not fully recharge the battery.
- Turn everything off before you shut down. Lights, heater fan, and chargers add to the load at the next start.
- If it won't start, do not keep cranking. Long cranking attempts can drain what is left. Check your owner's manual before jump-starting, especially on a newer car.
Battery trouble is just one of several things that show up with the first freeze. See our winter car checklist for the full list, and if a warning light is on, see our check engine light guide. Cold also triggers the tire pressure light.
FREQUENTLY ASKED QUESTIONS
TOUGH START? GET YOUR BATTERY TESTED
Walk-ins welcome · We test batteries · Tell us what the car is doing when you turn the key
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Sources: Firestone Complete Auto Care: when to replace a car battery · Les Schwab: battery or alternator? · CBS Philadelphia: AAA on cold weather and car batteries (2018). Percentages and battery ages are general figures from these sources and vary by battery and vehicle. This guide is general information, not a diagnosis of your car.
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