Cold weather is the bane of any car battery, slowing the chemical reaction inside that creates power. Freezing temperatures can slow the engine too. Preparing your car’s battery for winter and knowing what to do if it dies is key to ensuring its longevity.
Key Points
- Cold weather is very taxing on a car’s battery, slowing the internal process and reducing its strength by as much as 65 percent.
- Motor oil can thicken in subzero temperatures and slow the engine, requiring more power from the battery and stressing it further.
- A multimeter should cost around $50 and is used to test batteries to ensure they’re holding a charge; or a shop will likely check for free.
- If your battery dies, jumpstarting it is simple and shouldn’t take more than a few minutes.
- Protect your car’s battery from cold weather by wrapping it in a battery blanket, being mindful of corrosion, and opting for longer drives.
Cold Winter Temperatures Negatively Affect Your Car’s Battery
Car batteries work like most others: A chemical reaction occurs inside, producing and storing electrical energy, which your vehicle then uses to start the engine. However, cold weather can slow this reaction, stressing the battery. Frigid temperatures can also thicken motor oil, resulting in your battery needing to work harder to keep up.
Subzero Weather Slows Electrochemical Reaction Inside a Car’s Battery, Reducing Longevity
The most common car battery type is a lead-acid SLI (which stands for starting, lighting, and ignition). Once running, the alternator keeps most engine components and systems going and recharges the battery after it’s drained by about five percent.
In cold weather, the electrochemical reaction inside the battery slows, losing approximately 35 percent of its strength at 32 degrees, and as much as 60 percent at zero. Repeated deeper draws of the battery in cold climates can reduce its longevity. This is especially true if you don’t drive it long enough to replenish what’s lost.
Where a car battery would usually last three or four years, winter weather can cut this short where you might need a new one every two years or so.
Freezing Conditions Thicken Motor Oil, Putting Extra Stress on the Battery
Cold weather can also cause motor oil to thicken, slowing the engine. When this happens, more juice is needed from the battery to compensate, putting extra stress on it and decreasing its lifespan. Combine this with a battery that’s already being tested and isn’t running at full strength, and there may not be enough power to turn the engine over.
Opting for a higher viscosity oil designed for colder climates will help with this issue, especially if it’s a synthetic/synthetic blend, which tends to perform better in subzero temperatures. Be sure to check your owner’s manual to find out the recommended oil type for your vehicle.
Test Your Car’s Battery at Home Using a Multimeter, or Bring it to a Shop for a Free Test
Some of the most common signs of a dead battery include clicking sounds when trying to start the engine, a sluggish ignition, flickering/dim dome lights, and of course, the car not starting. If you do have a dead battery, you may just need to jumpstart it. But if the battery is no longer able to hold a charge, a replacement is likely needed.
To test if a car battery is losing charge, you have two options: Use a multimeter at home, or take your car to a shop. Most shops will perform a battery test free of charge in hopes of earning your business on the new unit. If you prefer diagnosing the issue yourself, a multimeter should cost about $50 at your local auto parts store.
Following this video from YouTube’s Chris Fix, here’s how to use a multimeter to test for a bad battery:
- Step #1: Turn on the headlights to use up any remaining surface charge.
- Step #2: Set the multimeter to between 15 to 20 volts.
- Step #3: Turn the headlights off.
- Step #4: Connect the multimeter to the positive and negative terminals (red to red, black to black).
- Step #5: If readings don’t show around 12.6 volts, the battery may be compromised.
- Step #6: Try and start the engine. If voltage shows below 10, it’s going out. If it’s less than five, it’s already bad.
Jumpstart a Car with a Dead Battery in Four Easy Steps
To jumpstart a car with a dead battery, all that’s needed is a pair of jumper cables and another vehicle.
Here’s how to jumpstart a car:
- Step #1: Park the running vehicle nose-to-nose with the bad battery and turn the engine off.
- Step #2: Attach the jumper cables to each car’s positive and negative terminals (red to red, black to black).
- Step #3: Start the vehicle with the charged battery first, then try and start the one with the dead unit.
- Step #4: If the engine starts, let it run for a few minutes before disconnecting the cables, and then turn it off and try again.
Tips for Protecting a Car’s Battery from Cold Climates
Watch for Signs of Corrosion
Keep an eye out for corroded battery terminals, which can drain power and inhibit the engine from starting. You can either clean the terminals yourself at home using some water with baking soda and a steel-wool brush, or have a shop do it for a minimal fee.
Regularly Change Your Motor Oil
Motor oil can affect your battery if it’s too thick, be it from cold, or age. Be sure to follow the recommended oil-change schedule for your car to ensure the battery doesn’t have to work harder than it needs to.
Install a Battery Blanket
As its name implies, a battery blanket wraps around the unit and insulates the core in subzero temperatures so it doesn’t freeze. Expect to spend $30 to $50 for a decent battery blanket at your local auto parts store.
Opt for Longer Drives Over Shorter
Typically, the alternator doesn’t begin recharging the battery until its charge is down about five percent. If you often take short trips and don’t allow the battery time to recharge, you’ll wear it out, or at least reduce its lifespan.
Cold Weather is Harmful to Car Batteries, but Proper Care and a Close Eye Should Ensure They Last
Most SLI batteries should last for about four years, but in cold temperatures, expect about half of that. Your best bet to keep the battery usable as long as possible is to prepare your car for winter. This means using the right motor oil to prevent it from thickening and wrapping your battery in a specialty blanket to keep it from freezing.
If the battery dies, test if it’s holding a charge with a multimeter. Otherwise, jumpstarting it with a pair of jumper cables is simple and should have you back on the road in no time.
Photos: Deposit Photos
