How Does the Cold Affect Your Car Battery?

Power - by Joe Weber - updated on 10/6/2023

A couple of months ago we talked about what the relentless summer heat can do to your car or truck battery. It's that time of the year when we need to talk about what happens to your battery in the bitter-cold winter months. The cold is right around the corner, and it's best to be ready for winter before it's too late.

What Happens to Lead-Acid Batteries in the Cold?

Lead-acid batteries are a lot like us. When it starts to get cold, we have to work harder to stay warm and produce the same level of work that we did in the summer. Car batteries are no different, as the temperatures drop there are several things that will start to occur inside your battery.

• Reduction in capacity
  As the temperature falls during the fall and winter months, the capacity of the battery also falls. Once the temperature reaches freezing, 32°F, the battery's capacity is reduced by around 20%. When the temperature reaches -22°F the capacity is reduced by 50%!
• Slower charging
  As the temperatures drop and it gets colder outside, batteries will recharge at a slower rate.
• Freezing electrolyte
  Yes, your car battery can actually freeze if it gets cold enough, especially if it isn't fully charged.

The electrolyte solution in your car battery is made up of sulfuric acid and water. This combination mixes when the battery is charged, which helps it resist freezing. A fully charged car battery won't freeze until the temperature reaches -76°F. Leaving the battery in a partially charged state, when the solution isn't mixed, can cause the battery to begin freezing at 32°F.

What Does That Mean for Your Car?

If you are one of the millions of Americans who park their cars outside, you will probably run into these issues in the winter. If you are from the midwest you probably remember the polar vortex of 2019   when wind chills dropped below -55°F. During that time, car batteries were showing all of the typical cold weather symptoms.

Story Time

The first deep freeze of the season is coming tonight. You drive home from your office, which is only about 3 miles away. You pull into the driveway and open the garage door. You can't park in there because it's filled with tools, kids' toys, and gardening supplies. So, you park in the driveway, lock the doors and greet your family in the kitchen.

The temperature drops below zero overnight with a strong wind. In the morning, you get ready to leave for work at your usual time and walk outside. You sit down in the freezing car and turn the key. A very slow crank can be heard and then nothing happens. Now you are going to be late for work trying to get the car started or waiting for a ride.

What happened?

With the car being left outside in the elements, all three of the above things happened.

1. Such a short drive didn't allow the battery to charge back up after using energy to start the engine. With the outside temperature low, the battery charged slower than usual.
2. The sub-zero temperatures reduced the capacity of the battery by about 50% leaving it without the cranking power it needs to start the engine.
3. Without letting the battery come to a full charge it was much easier for the electrolyte to freeze.

What Can I Do to Keep This From Happening?

Don't worry though. Sometimes we have no choice other than to park outside. There are several things you can do to keep your battery in healthy condition through the winter months.

• Plug it in
  Connecting your battery to a battery maintainer will not only keep the battery charged, but it will also keep the battery active and ready to provide power. As the battery charges, heat is generated which will help keep the battery in a ready-to-crank state when you have to leave in the morning.
• Keep it clean
  If you've heard it from us once, you've heard it a thousand times; corrosion kills batteries. Keep your battery terminals clean and corrosion-free with a battery terminal protection kit. Corrosion is more common in the hot summer months but it is still a good practice to clean the terminals before the temperature drops.
• Park in a garage (if you can)
  Even though many home garages are not insulated, they still provide protection against the winter elements. Parking in the garage could be the difference between getting to work or school on time, or not.
• Remember to turn off the headlights
  We all do it. Even with automatic headlights, it seems like somehow the setting gets changed to manual and we leave the lights on. Leaving the headlights on will create an additional power draw from the battery causing it to drain much faster.
• Choose the right battery for your climate
  Certain batteries are engineered to excel in low-temperature conditions compared to their counterparts. Whenever feasible, choose a battery with a higher Cold Cranking Amps (CCA) rating for reliable car starting, especially as it ages over the years.

Cold Weather Will Expose Your Older Batteries

Batteries naturally deteriorate over time. Generally speaking, a car or truck battery will last 3 - 5 years. If you have an older battery going into the bitter-cold winter months, you could be in for an unfortunate surprise that you will quickly experience. Cold weather will expose the need for a new battery very quickly.

This is one of the many reasons why you need to keep your battery healthy in the summer and drive over to Batteries Plus before the cold hits to have your battery tested to see if you should replace it before problems arise.

What's the Best Battery for Cold Climates?

Nothing is worse than having to deal with battery issues in the bitter cold. Having a battery that is designed to perform in the cold is your first line of defense against winter battery woes. The best battery for use in cold climates is an Absorbed Glass Mat (AGM) battery. Instead of a loose electrolyte solution seen in flooded car batteries, AGM batteries have the electrolyte solution absorbed into a fiberglass mat, tightly weaved in between the battery plates.

I know what you're thinking, "What does that have to do with it being better in the cold?". Let me explain.

• The tightly packed mats provide freezing resistance in colder temperatures. AGM batteries are not freezeproof, if it is cold enough even these batteries will freeze.
• It also allows the battery to produce more Cold Cranking Amps (CCA) to crank the engine in the cold.
• AGM batteries are completely sealed so you don't have to worry about electrolyte leaking.
• AGM batteries take the produced gasses and mix them back into the electrolyte. Meaning, that there is a much lower chance of corrosion on terminals and surrounding parts.

Thanks to the design of AGM batteries, they are superior to flooded batteries in the cold. These batteries are also much better in the heat, so they really are the best batteries you can get for your car or truck.

What AGM Batteries Does Batteries Plus Carry?

Batteries Plus carries a large selection of AGM car and truck batteries from brands such as Duracell Ultra, Optima, Odyssey and of course our own premium brand X2Power.

We love all batteries but X2Power batteries will always have a special place in our hearts. Our X2Power batteries have the backing of over 30 years of battery experience built into each battery. All of our X2Power batteries are engineered by enthusiasts (yes, we love cars and trucks too) for enthusiasts.

You won't just get great all-climate performance. You will also get more rugged batteries for rough terrain, pure lead internals for more power and corrosion resistance, longer warranties and 3 times the life vs. flooded batteries. Stop by your local Batteries Plus today to see them today!