Do I need to replace my car battery?

The car 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 car battery is failing? How long does it last? Let’s start with why the battery needs to be replaced.

Most cars have lead-acid batteries that are made of six cells with lead and lead-oxide plates filled with an electrolyte (dilute sulfuric acid). Over time, a lead-acid battery loses some of its capacity, mostly due to sulfation. At some point, the capacity will drop so low that the battery won’t be able to start your car.

How long can it last?

An average car battery lasts from 2 to 4 years. Usually 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. The battery lasts longer when it’s kept fully charged, although overcharging can also damage it.

Therefore, problems with your vehicle’s charging system can also cause the battery to fail prematurely.

 

Is there a way to tell your car battery is failing ?

Is there a way to tell that the battery is failing? Not always, but there are some telltale signs.

When the battery is failing, it loses its capacity, meaning it can hold less charge than when it was new. If your battery has low capacity you may notice that when you are starting the car, the engine turns over slower than before, even if the battery is fully charged.

It sounds like the starter motor is “lazy” and not as eager to turn over your engine. You may also notice that the interior lights flicker and go dimmer than usual when you are turning over the engine.

 

Do you need to maintain a car battery ?

Does the car battery need any maintenance? Most modern batteries are maintenance-free. You can verify this in the owner’s manual for your car. Typically, the car 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.

 

What can cause a car battery to drain quickly ?

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.