Why Do Car Batteries Die in Winter?

Car battery being serviced at our workshop

With winter just around the corner, it’s time to talk about a crucial aspect of car maintenance that often gets overlooked until it’s too late – your car battery.

Colder mornings can be brutal on your battery, and I’ve seen more than a few simply cark it when the weather gets too cold.

But why do car batteries fail in winter? Well, it’s a combination of things including increased strain from heating and the slowing of reactions inside the battery. Read on for a more in-depth answer!

Why Do Car Batteries Die in Winter?

When the temperature drops, your car battery has to work a lot harder. Cold weather slows down the electrochemical reactions inside the battery, reducing its efficiency. Below is a more technical breakdown of why batteries often cark it in winter:

  • Reduced Capacity: At 0°C, a battery’s capacity is reduced by around 20%, and at -18°C, it can drop by up to 50%. This decrease in capacity means the battery has less power to turn over the engine.
  • Increased Power Demand: Winter conditions require more from your car’s electrical system. Using the heater, defroster, and headlights increases the demand on your battery, which is already weakened by the cold.
  • Thicker Engine Oil: Cold temperatures cause engine oil to thicken, increasing the resistance when the engine turns over. This requires more cranking power from the battery, which may already be struggling due to the cold.

These factors combine to create a perfect storm for battery failure during winter. It’s why a battery that seemed fine in summer might suddenly leave you stranded on a cold morning.

How Temperature Affects Car Batteries

Batteries operate best at around 25°C, so winter conditions are far from ideal.

Warm Weather

In warmer temperatures, your battery operates efficiently because the chemical reactions occur at an optimal rate. This means your battery doesn’t have to work as hard, and its capacity remains stable. Heat, while it speeds up chemical reactions, also accelerates internal corrosion and degrades the battery over time, reducing its lifespan.

Cold Weather

As temperatures drop, the chemical reactions inside the battery slow down. This reduction in reaction speed means your battery’s ability to produce power is compromised. For instance, at -18°C, your battery’s efficiency can be cut in half, making it much harder for your engine to start. Cold weather also thickens engine oil, increasing resistance and requiring more cranking power from the battery, which may already be struggling due to the cold.

Understanding these factors can help you take the necessary steps to ensure your battery is up to the task during winter. Regular checks and maintenance can mitigate these effects, keeping your vehicle reliable in cold weather.

Why You Should Understand Your Cold-Cranking Amperage

Now that we’ve covered how temperatures affect your battery, let’s talk about Cold-Cranking Amperage (CCA). CCA is a critical measure of a battery’s performance in cold weather.

CCA measures the amount of current a battery can deliver for 30 seconds at -18°C without dropping below 7.2 volts. It’s a key indicator of how well your battery can start your engine in cold conditions.

A higher CCA rating means your battery can deliver more power in cold weather, making it easier to start your vehicle. This is crucial in winter when your engine requires more cranking power.

Fully charged batteries can handle temperatures down to -50°C, but if the battery is low on charge, it can freeze at just -1°C. This freezing can cause irreparable damage to the battery cells.

Understanding CCA and ensuring your battery has a sufficient rating for winter conditions can prevent unexpected failures.

It’s a good idea to have your battery’s CCA tested before the cold sets in to ensure it’s up to the challenge.

Common Signs of a Failing Battery

Spotting the early signs of a failing battery can save you from getting stranded on a cold morning. Here are some common indicators to watch for:

  • Slow Engine Crank: If your engine takes longer to start than usual, it’s a sign that your battery might be weakening.
  • Dim Lights: Headlights that appear dimmer than usual can indicate a low battery charge.
  • Clicking Sound: Hearing a clicking noise when you turn the key is often a sign that the battery doesn’t have enough power to start the engine.
  • Electrical Issues: If your power windows, radio, or other electrical components are not working properly, it could be due to a failing battery.
  • Swollen Battery Case: A swollen or bloated battery case is a sign of excessive heat or overcharging, which can significantly reduce the battery’s lifespan.
  • Check Engine Light: Sometimes, a failing battery can trigger the check engine light on your dashboard.

Can Car Batteries Freeze in the Winter?

Most car batteries can freeze at around -40°C. Once frozen, the battery starts to expand and can cause cracks or ruptures.

DIY Battery Maintenance Tips

Regular maintenance can extend your battery’s life and ensure it performs well during winter. Here are some practical tips:

  • Check Terminals: Ensure that the battery terminals are tight and free from corrosion. Clean them regularly to maintain a good connection.
  • Inspect Fluid Levels: If your battery has removable caps, check the fluid levels and top them up with distilled water if necessary. Fluid levels should be above the plates.
  • Clean Corrosion: Use a mixture of baking soda and water to clean any corrosion on the battery terminals. This helps maintain a good electrical connection.
  • Use a Multimeter: Periodically check the battery voltage with a multimeter. A fully charged battery should read around 12.6 volts or higher.
  • Drive Regularly: Keep your battery charged by driving your car regularly. Short trips don’t allow the battery to fully recharge, so try to drive for longer periods when possible.
  • Avoid Short Trips: As mentioned, short trips don’t give the battery enough time to recharge fully. Combine errands to reduce the number of short trips.
  • Insulate the Battery: Use a battery blanket to protect it from extreme cold, which can help maintain its temperature and performance.

How to Prepare Yourself for Winter Driving

Even with the best care, car batteries can still fail unexpectedly. To avoid getting stuck, it’s essential to be prepared with the right tools, such as:

Battery Chargers

Keeping a battery charger on hand can be a lifesaver. A good quality charger maintains your battery’s health, ensuring it’s always ready to go. This is particularly useful for those who don’t drive daily or have multiple vehicles. Battery chargers work by gradually replenishing the charge, helping to extend the battery’s lifespan. I recommend the AC battery chargers from Redarc Electronics for their reliability and efficiency.

Jump Pack Kits

These portable power packs can jump-start your car without needing another vehicle, making them incredibly convenient. They’re compact, easy to store in your boot, and can provide a quick boost to get your engine running again. A jump pack kit is an excellent backup plan, especially during winter when battery failures are more common. It’s like having a set of jumper cables and a second car all in one portable unit.

Self Jump-Starting Button

If you’ve got a dual battery system, we can set you up with a self jump-starting button. This nifty addition allows you to jump-start your car with the push of a button, using your second battery.

It’s a seamless solution that ensures you’re never stuck with a dead battery. And if you don’t have a dual battery system yet, no worries—we can install one for you!

A dual battery system is particularly beneficial for those who enjoy off-roading or camping, providing reliable power for all your adventures. For more information, check out our dual battery installation services at Voltaic.

Visit an Auto Electrician

At Voltaic Auto Electrical, we offer a range of battery-related products and services to meet your needs.

Our knowledgeable staff can help you choose the right equipment and provide expert installation to keep your vehicle running smoothly all winter long.

Don’t get caught out in the cold—equip yourself with the best battery solutions from Voltaic Auto Electrical.

Get Your Battery Checked

Don’t let a weak battery ruin your winter plans. Swing by Voltaic Auto Electrical for a thorough battery check and check out our range of chargers, jump packs, and dual battery systems.

Our knowledgeable staff are here to ensure your vehicle is reliable through every season. Visit us at Voltaic Auto Electrical or contact us today for expert advice and top-notch battery services.

Don’t wait until you’re stranded – let us help you stay on the road this winter!