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Whether you’ve purchased a new battery or you are still running with the original battery, it’s important to understand how long car batteries last. Find out today what you can expect from your battery and signs to look out for that indicate it’s time to replace your battery. If it’s time to replace your battery, head to America’s #1 battery destination.

Average Battery Lifetime and Charge

Batteries live a mysterious and misunderstood life. While some batteries offer clues that failure is coming, many do not. While we’d all like to have an avid array of warnings that battery failure is coming, it’s good to first prevent some of the big issues causing battery failures, and next, react quickly when clues present themselves that something may be wrong.

It’s important to remember that no battery lasts forever, but certain things can reduce the life of a battery, sometimes very quickly. Whether you’re keeping your car in storage all year or driving it every day, you’ll still need to replace your battery at some point. Typically, a car battery will last between three and five years. Pushing a battery longer than five years, even under perfect driving conditions, could cause your battery to fail without notice. For that reason, many manufacturers recommend a replacement schedule of five years.

When your battery is reaching three or more years old, consider having it tested. AutoZone can quickly test your battery, along with your charging system to make sure that your battery is working properly, and the charging system is getting the battery the charge needed to maintain it when running.

Why Do Car Batteries Die?

Car batteries are designed for one purpose – provide a powerful, quick, high-amperage current to the starter to start the car, and then constantly have this charge of 12.4 volts maintained by the alternator once the car is running. The following things, however, can cause a battery to either not retain that charge, or not supply the proper current to start the car.

  • Slow discharging / recharging: All batteries, if left untended, very slowly discharge from 12.4 volts. But unlike its cousin, the deep-cycle battery, a car starting battery is not meant to be discharged beyond it’s starting cycle, and charged again over a multitude of times. Often times, this rears its ugly head when a battery is left in a vehicle that hasn’t started for a long period of time, or, the vehicle has a parasitic drain, or draw, that is stealing voltage as the car sits. When this happens, in most cases, the battery must be re-charged, or worse yet, the car is jumped and the alternator is left to do the work of charging a dead battery, which it’s not meant to do. Either way, a starting battery can only take so much of this before it loses the ability to be recharged. More so, time can wear on a battery here, where after so many years and start cycles, the battery again loses its ability to maintain a charge. This often times becomes very apparent in frigid temperatures, where an engine needs more amperage to start, and a cold battery supplies even less.
  • Structural failure: Batteries are made up of a series of lead grids, submersed in electrolyte, which in this case is Sulfuric Acid. They also live a hard life, being bumped around with a car’s movements and suspension, and subject to massive, rapid temperature changes either inside an engine compartment, or going from a hot summer day to freezing temperatures in the winter. Because of this, some batteries can simply have an internal structural failure, which many people have labeled a “dead cell”. Many times, failure is due to a loss of electrolyte, which causes one of the grids, or cells, to become exposed to the air. The battery is fine one minute, next it’s not, it cannot take a charge, and therefore must be replaced when any structural failure happens.
  • Rapid discharging, overcharging / alternator failure: Similar to slow discharging, a rapid discharge/overcharge often happens when an alternator – the battery’s source for maintaining charge, fails and causes issues. If an alternator begins to over-charge the battery, the electrolyte can boil over, leak, and eventually the battery fails. Opposite of this, if the alternator stops charging, or a break in the charging circuit between the alternator and battery happens, the cars entire electrical and ignition system is now running off of the battery, which causes a quick and rapid drain. This failure also triggers the Battery Light, which is a bit of a misnomer as the Battery Light indicates that your charging system is not charging the battery, not that the battery is suddenly bad. In most cases, if an alternator issue is quickly identified, fixed, and the battery is properly recharged, the battery can be saved. Many times, however, the battery often fails at the same time as the alternator, due to this rapid discharge, and many days until it’s discovered.

Signs That Your Battery is Failing

Batteries don’t always provide you with clues that there’s a problem brewing, but many times they do. Remember that any battery over 3 years should immediately be suspect, as the clock is marching towards failure quickly. Check for any of these items below and if any are present, get the battery tested at AutoZone immediately :

  • Slow starting: When temps drop below 20 degrees, generally any car’s starting cadence will slow down. Get below 0 and it gets even slower. If you notice this behavior – a slow, dragging start suddenly begin, get your battery tested as soon as possible and don’t ignore it. Eventually, the car will not start. If a slow starting battery seems to be able to take a charge and test fine, it’s likely that a parasitic drain, or draw is discharging the battery while the vehicle sits, and the electrical system will need to be looked at.
  • Signs of leakage or corrosion: Check the tops of the battery for corrosion, or signs of acid in the battery tray below. While corrosion on the terminals doesn’t spell a dying battery, that corrosion will eventually lead to a failed terminal. Leakage can often signal a structural failure or over-charging.
  • Sudden click or no-start: If suddenly your battery is dead – meaning, you turn the key and get a click or buzzing, jumping the car and going about your day is not the solution unless it’s an emergency. Many times, the headlights or dash lights will work fine, but the car will click when you try to start it. Get the battery charged and tested immediately, along with other parts of the charging system. If the issue continues after battery replacement, the chances of a parasitic drain, or draw on the battery are likely and it will need to be checked out.
  • A very bad smell: The tell-tale sign of Sulfuric acid is a rotten-egg smell. If you smell this, the chances are your battery is very unstable, and more than likely either being over-charged, or has an internal structural failure.

How to Prevent Battery Failure

Routine testing and keeping track of your battery’s lifespan will give you a clear idea of when to replace a car battery. As your battery nears the end of its life, it’s time to consider the best battery replacement and budget for a replacement. In the meantime, however, several things can be done to get the most out of your battery life.

  • Long time between starts? Use a maintainer: A battery maintainer keeps an on-demand low-amperage charge on your battery, eliminating any slow discharge. Remember, that slow discharge, and recharge will eventually kill a perfectly good battery. Learn more about different types of battery chargers here.
  • Get the corrosion off: Periodically check the battery terminals for corrosion, and keep the posts and clamps clean. Battery corrosion washers, and dielectric grease will help aid in keeping corrosion at-bay.
  • Don’t power accessories for long periods: Again, your car battery is used for starting, not accessories. If you are someone who throws the stereo on in the truck out at the campsite to listen to the football game over the weekend, or spend any time powering items with the car off, consider either an auxiliary battery, or a deep cycle / starting combination battery that is better suited for discharge / recharge.
  • Don’t remove heat/protective blankets: Many vehicles come equipped with protective heat blankets or shields around the battery. Over time, these devices break down, or get removed and discarded. Don’t be tempted to do this and these are designed to protect the battery from the hot elements under the hood.
  • Test your battery frequently: Finding out your battery is bad in a frozen, empty parking lot at night is bad. Finding out your battery is needs to be replaced while getting tested in an AutoZone parking lot is way less stressful.

Whatever new battery you choose as your replacement, the important thing is to keep track of what’s going on with your vehicle and know when you need to test or replace the car battery. You may not experience any warning signs, but a battery test and consistent schedule are essential for preventing sudden failure. Whether you replace your battery every three years or extend its life to six years or more, carefully monitor its power and ability to maintain a charge. This will reduce your odds of being stranded and keep your vehicle powered as you cruise down the road.

Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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