When does a car battery need to be replaced?

Car battery The battery is what powers every electrical component in a car. At some point, the car battery needs to be replaced, but when? Is there a way to tell that the battery is failing? How long can it last? Is there a way to tell that the battery is failing?

Signs of a weak battery

When the battery is failing, it loses its capacity, meaning it can hold less charge. If the battery in your car has low capacity, you may notice that when you are starting the car, the engine cranks slower than before. It sounds like the starter is “lazy” and not as eager to turn over your engine. You may also notice that the interior lights flicker and become dimmer than usual when you are starting the engine.

My car needed to be boosted. Should the battery be replaced?

If a vehicle needs to be boosted, it means that the battery doesn’t have enough charge. Even a good battery can be drained if the vehicle is parked for a long time or some electrical device or light is left on. Once the vehicle is boosted and started, the vehicle’s alternator supplies the electric power and recharges the battery. If the vehicle re-starts fine after running for 10-20 minutes, the battery might still be OK.

Battery testing

Is there a way to test the battery condition? Yes, your mechanic can test your battery with a battery tester. Car dealers and many independent repair shops have a computerized battery tester (in the photo) that not only can tell the state of the battery, but can also test the charging and starting system. Battery tester
The battery and charging system test costs from $35 to $60, or it could be offered for free as a part of a seasonal promotion.  You may also get the test printout that indicates the current capacity of your battery and measurements of the starting and charging systems. The test will show if the battery needs to be charged or replaced. If your battery is very old, you might consider having it replaced rather than paying for the battery test. A battery also needs to be replaced if it is leaking or has any mechanical damage.

How long does an average battery last?

The battery lasts longer if the vehicle is driven daily. If the vehicle is parked for extended periods of time without starting, the battery will need to be replaced sooner.
When the battery is old, it becomes fragile. Any small shock can cause it to fail. Often an old battery dies after a dome light or some other electrical device was left on in a car overnight. Even hitting a large pothole can cause an old battery to fail. An average car battery lasts from 5 to 7 years.

Battery warranty

Is a battery covered under warranty? Yes, in most cars, the battery is covered under a basic bumper to bumper warranty. In some cars, the battery coverage is pro-rated. This means, for example, the labor might be fully covered, while the part might be covered 100 percent within the first year, 50 percent within the second year and so on. In other cars the battery replacement is covered 100 percent part and labor within the warranty period. You can check the warranty coverage details in your Warranty Guide brochure, or on the manufacturer’s website.

Battery replacement

How expensive is it to replace a battery? A new car battery costs from $60 to $130 and your dealer may charge another $30-$80 to have it replaced. Replacing a car battery as a do-it-yourself project is not very difficult but the battery is quite heavy. Lifting it out of the car can be hard on your back. An old battery could be covered in electrolyte, which is very acidic and can burn your clothes or skin. Here is the DIY battery replacement guide from Pep Boys.

If the battery is replaced without using a memory saving device, the automatic power windows and idle control will need to be reset. Read more: Common problems after replacing the battery and how to avoid them.

Battery maintenance

Corroded battery terminal

Does the battery need any maintenance? Most modern batteries are maintenance-free. You can verify this in the owner’s manual for your car. Typically, the battery is checked visually during your regular oil changes. Your mechanic may recommend servicing your battery terminals if there is some corrosion at the terminals (in the photo), which is not uncommon. Servicing battery terminals is not very expensive ($30-$50).

What does the battery icon on the dash mean?

Does the red battery warning light on the dash mean the battery is bad? The red warning icon on the dash depicting a battery indicates a problem with your vehicle’s charging system. If it comes on while driving, it means your that battery is not charging. The battery may still be okay, but the charging system needs to be tested. The main component of the charging system is the alternator. Your mechanic can test the alternator with the same computerized battery tester we mentioned above.

Battery current draw testing

What may cause a car battery to drain quickly (e.g overnight)? Either the battery has an internal defect or some electrical component in the car stays on and drains the battery. A battery test will usually show if the battery has an internal defect. If the battery tests OK,  your mechanic may recommend a parasitic current draw test. The test involves  measuring the current draw after all electrical devices are turned off, and comparing it to the specifications. Typically, the current should be less than 50 mA (milliamps) after the car was shut off for 20-30 minutes. If the parasitic current draw is higher, the electrical component that draws extra current needs to be identified and replaced. The diagnostic process involves disconnecting various circuits and re-checking the current draw. This process could be time consuming.

Read next: Common problems after replacing the battery and how to avoid them