How Long Do Car Batteries Last?

You rely on your car’s battery to start your car every time you turn the key. Whether you are driving to work or just hitting the road for a day of fun, you need to know that your battery is up to the job. Unfortunately, batteries don’t last forever, and even new car batteries will eventually need to be replaced.

How long should the battery in your vehicle last? The answer isn’t always straightforward, and in many cases, it isn’t as long as drivers think it should be.

Car Battery Lifespan and What Causes Batteries to Fail

The average life expectancy of a car battery is three years or so, but there are several factors that can have an impact on that estimate. Even under the most ideal conditions, chemical reactions cause batteries to break down, and your vehicle will likely need a new battery within a few years.

Though car battery problems are often associated with cold weather, Consumer Reports magazine says heat is a bigger enemy of car batteries and will take a bigger toll on performance and reserve capacity. Heat can also decrease a battery’s lifespan significantly. Hot weather causes liquids inside batteries to evaporate as well as internal damage. This can occur whether you are driving or if the car is parked. The magazine recommends that vehicle owners in hotter parts of the country have their car battery tested after two years of ownership and then every year after. Those who live in colder areas can wait four years after buying a car to test performance and capacity, then every year after.

“Heat kills car batteries,” according to John Banta, a Consumer Reports project leader and part of the team that tests batteries for the magazine. “Many times in cold climates, your battery fails to start your car on a below-freezing day. The reason this happens is that the heat of the past summers has weakened your battery. When you use it in the cold, the starter requires more electrical current to turn over the cold engine with its thickened oil.”

Leaving your car parked or stored for long periods of time can also lead to a dead battery that you will need to recharge before heading out for a drive.

Testing a battery’s performance and reserve (or amp-hour) capacity is not just a matter of seeing whether it will hold a charge (or checking the electric eye found on some batteries to see if it is green), so testing is best done by an auto technician at a repair shop. A professional can also determine if any problems you are having may be caused by something else, like your battery terminals or alternator. If a bad battery is the culprit, your mechanic will help you choose and install an appropriate replacement.

When to Change Your Car’s Battery

There are several signs that indicate the battery in your car is failing and needs to be replaced. Sluggish engine cranking and unusual electrical problems like flickering headlights are telltale signs of trouble, though they may also indicate problems with your car’s alternator. You should also replace your battery if it is bulging or has a rotten egg smell.