How long does a car battery last?

how to change a car battery
Ronan Glon/Digital Trends

Your car’s battery falls into the wear-and-tear category. It’s not a part designed to last for the entire life of your vehicle, and there are a number of factors that can shorten its life expectancy. How long you can expect your car’s battery to reliably do its job largely depends on where you drive, what you drive, and how you drive it.

On average, a new battery lasts approximately five years in ideal conditions, though your mileage may vary. By ideal conditions, we mean that the car’s electrical system is in tip-top shape, that the battery regularly goes through full charging cycles, and that it’s not subjected to extreme temperatures on a regular basis.

To elaborate, your car’s electrical system consists of many parts like the alternator, the voltage regulator, plus a real latticework of wires and grounds. An issue with any of the above could shorten your battery’s life expectancy if it’s ignored. Preventive maintenance goes a long way here. Keep an eye out for early warning signs, like headlights that dim when you turn on the heater, or instrument panel lights that are markedly dimmer than the day you bought the car.

As for full charging cycles, keep in mind your car’s 12-volt battery dispenses a significant amount of electricity to zap the starter motor into motion every time you start the engine. If your commute is half a mile long, the alternator might not have time to recharge the battery. We’re not saying you should live further from work, but if you only drive short distances, take your car on a 20- to 30-minute trip and every now and then to ensure the battery gets the full charge it needs.

The effect that freezing-cold temperatures have on a car battery are relatively well known. An engine requires more energy to start when the thermometer dips into the 20s, or below, partly because the oil gets thicker. At the same time, the cold makes the battery less effective. It’s weaker, yet it needs to work harder, and that’s not a good combination. What many motorists don’t realize is that hot weather takes an even greater toll on their car’s battery, and the cause of a dead battery in November might be the July heat. While starting is often easier in the summer, rising temperatures under the hood — where many batteries are located — cause the water in the electrolyte solution to evaporate, and cause the plates to corrode.

This is less of a worry if your battery is in the trunk, or under the rear seat, though it will still get hot. And, ultimately, there’s not a lot you can do to keep it cool. The best measures you can take are to test your battery on a regular basis, preferably in the spring and in the fall, and to keep a set of jumper cables in the trunk, or under one of the front seats.

What happens if your battery dies?

how to change a car battery
Ronan Glon/Digital Trends

Don’t fret if you’re stuck with a dead battery. Whether you’re in in your driveway, at work, or in the middle of a road trip, there are ways to get your car running again so that you can drive it home, or to the nearest repair shop. If your car has a manual transmission, you can start it by pushing it, putting it in second gear, and releasing the clutch once you’ve built up enough speed. Note you’ll probably need at least one helper to pull this off. Alternatively, a good set of jumper cables and a second car will channel enough electricity to your battery for it to turn the starter motor. There are also now jumper packs that achieve the same result without needing the second car.

Lastly, changing a car battery is easier than it sounds. Broadly speaking, it’s a task that takes no more than 10 minutes, doesn’t require advanced knowledge, and can be completed with only a basic set of tools and simple precautions.

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