Does Cold Weather Drain the Car Battery?

Cold weather affects your car as much as it affects you. In particular, it affects the car battery, causing it to lose power and potentially fail.

Fortunately, you can protect the car battery from the debilitating effects of cold weather. If you know the leading causes of car battery drain in low temperatures, you can take steps to correct them.

Will Cold Weather Drain A Car Battery?

There’s no denying that cold weather plays a significant role in car battery drain. As a matter of fact, cold weather will reduce the capacity of just about any battery, including electric vehicle and hybrid vehicle batteries.

But while low temperatures increase the risk of the battery discharging or dying, it’s not the only reason. Sometimes, it’s not even the primary culprit behind battery issues.

In some cases, cold weather aggravates earlier issues that drain the battery. Therefore, it’s vital to identify the exact cause of the problem to prevent it from reappearing down the line.

How Does Cold Weather Drain Car Batteries?

So, what drains a car battery in cold weather? Here are the leading reasons:

Lower Car Battery Capacity

When you start your car, the battery supplies enough current to get the starter going and crank the engine. It propels charged particles through a medium, triggering a chemical reaction that releases power stored in the device.

Unfortunately, cold weather slows the movement rate of the charged particles in car batteries. A cold battery has a lower capacity than expected, which can interfere with starting and cranking the engine.

Older batteries are even more vulnerable to the detrimental effects of cold temperatures and sometimes cannot generate enough energy to start and crank the car when it’s cold out there. 

Reduced Charge Rate

While the battery initially powers the ignition system and essential accessories, it makes way for the alternator once the engine hits its stride. The alternator charges the battery, replenishing the energy expended during the engine start-up sequence. Nothing recharges your car battery better or faster than the alternator.

Cold weather not only reduces the overall capacity of the battery, it also slows down its charging rate. The alternator needs more time to top off the battery, so if it doesn’t get enough charging time, it can become depleted.

Thickened Engine Oil

The car battery isn’t the only part affected by cold weather. The engine can also develop problems when it gets cold. In turn, engine issues can affect the battery.

Engine oil, which greases the engine’s internal parts, becomes thicker and more viscous at low temperatures. Thickened oil flows more slowly, which increases the power and work required to turn over the engine.

So, how does this affect the battery? The battery supplies the power for cranking the engine. It must overcome the increased resistance by delivering more power, which drains it faster.

It gets worse. Cold weather also reduces the battery’s capacity to release power. If the underperforming battery cannot deliver enough power to meet the increased demand of an engine with thickened oil, your car might not start.

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: In extreme cold weather (like below 20 degrees Fahrenheit), even multi-viscosity oils become thick enough to restrict crankshaft movement when the engine is attempting its first start. This, coupled with the effect of the cold on the battery itself, can cause a vehicle to be difficult to start in extremely cold weather. This is one reason many northern vehicles have block heaters that are plugged in at night to keep the engine warm for an easier cold start in the morning.

Higher Power Demand

You usually operate more electrical and electronic features when it’s cold outside. You run the heater to stay warm inside your car, the defroster to eliminate frost on the windows, and the windshield wipers to remove snow from the glass.

The car battery provides the power to operate these parts if the engine isn’t running. While the alternator takes over the task once you successfully start the engine, the battery will supply additional power if the generator cannot produce enough energy to meet the heavy demand.

As long as the battery keeps releasing power instead of charging up, it cannot replenish itself. Eventually, it might become discharged, leaving you with a dead battery that cannot start your car.

Furthermore, the battery might suffer parasitic drain, an issue where a part keeps drawing power from it even when the car isn’t running. It can happen if you leave something operating or a part develops an issue with its circuit, leading to it continuously pulling power.

Between all the features you’re running when it’s cold, plus any parasitic drain, you might drain the battery faster than you realize.

How to Keep the Car Battery From Dying In Cold Weather

Now that you know how cold weather drains car batteries, what can you do to prevent it? Here are some tips and tricks to protect the battery from getting drained when it’s cold out there:

Get a Battery With a High Cold Cranking Amps Rating

If you often drive in cold weather, get a battery with a high cold cranking amps (CCA) rating. CCA is a rating system that determines the battery’s ability to start and crank the engine at 0°F (-18°C). The higher the rating, the more amps the battery produces during cold temperatures.

A battery with a high CCA rating will continue operating effectively no matter how cold it gets.

Park in a Safe Place and Shut Down the Security System

Does your car have an anti-theft system? While the security system provides peace of mind, it also drains the car battery, which can prove problematic when it gets cold outside.

Park your car in your garage or another safe space with external security. You can turn the security system off to reduce the drain on the battery without leaving your vehicle vulnerable to thieves.

Disconnect the Negative Battery Terminal

As long as the car remains connected to the negative battery end, it will draw power from the battery. Look for the connector with a minus sign or a black color. Disconnect and insulate it. When you need to start your vehicle, reattach the connector.

Thermal Battery Blanket

Get a thermal blanket to serve as insulation for the car battery. Made of material that captures and keeps heat, the blanket also has a heating element that runs on an external power supply. You can spread the thermal blanket over the battery to keep it warm during cold weather.

Engine Block Heater

Alternatively, you can get an engine block heater that warms the engine block and the battery. Not only will the heater protect the battery from cold-related lost capacity, it will also prevent the engine oil from thickening because of the cold weather.

Jump Starters

Sometimes, the car battery can die without warning during cold weather. You can jump-start it to get the engine running, allowing you to drive to where you can replace the discharged battery,

Cold weather can be a literal drain on the car battery. However, you can prevent its negative effects with some easy steps.