Car batteries are hardly new technology, they’ve been an integral part of the under-hood setup in cars for as long as anyone can remember. The humble 12-volt battery is found in every type of car, even modern and cutting-edge electric cars --- though the function has changed a little for EVs. It’s one of the components that even car owners with little to no technical knowledge also understand that they have, what it does, and what it means when they go wrong.
Below we provide a clearer understanding of car batteries, and especially how long they last, how you know when it’s time to get a new one, and more. The battery is a critical engine component and your car can’t operate properly without it. Keeping the battery in good health and ensuring that you always have a properly working unit is therefore essential.
Background: What Does the Battery Do?
First, let’s be very clear on what exactly the car battery does and which battery we are talking about. In this article, we are not referring to the huge lithium-ion battery packs that dominate the underside of electric vehicles. Rather, we are talking about the smaller 12-volt batteries that are typically located under the hood, although sometimes in strange other places on some car models, especially hybrids and EVs.
In short, the car battery is the component that provides that all-important spark of electrical energy that is needed to bring your car to life and get all of its electrical components working. The voltage from the battery is what powers up the starter that gets the engine turning over. It also provides the electrical power needed to run your in-car electronics.
Finally, it also works to stabilize the energy supply, which in turn keeps your engine running smoothly, keeps your lights at the right brightness, and stops your stereo system from flicking on and off in that annoying way it otherwise would.
All of that power and function is compacted into what is nowadays a pretty small box. The unit works using chemical reactions that turn chemical energy into electrical energy that the car can then use. One question some people have, especially after dealing with electric cars, is how does the 12-volt car battery stay charged? We haven’t had to plug our cars in until the likes of the Nissan Leaf and Tesla came along, so why doesn’t this battery need it?
The regular 12-volt battery is recharged by the alternator as the engine runs. In other words, the act of driving your car hither and thither is what keeps the battery charged. That’s actually how regular hybrid car lithium-ion battery packs work, too.
If you’ve ever left your car in the garage for many weeks and come to find it has a dead battery, the reason for that was the long period of inactivity. The battery needs activity so it can remain charged. A run of about 20-30 minutes each day is usually enough to keep the battery fully charged.
How Long Do Car Batteries Last?
It’s hard to say precisely how long a car battery will last, but the most typical scenario is that a car battery will last for 3-5 years under normal conditions. Extreme conditions and unforeseen events can lower that lifespan, of course, but 3-5 years is a very representative average for how long car batteries typically last for most car owners.
In battery terms, its lifespan is from the point of production and installation to the point where either it loses its charge and can’t be recharged, its chemistry becomes too imbalanced, or there is too much physical damage to make it viable. Car batteries definitely do have a limited lifespan, but it’s hard to say exactly when there are different degrees of the things that impact them most in different places and different cars. Three things actively work to reduce your battery’s lifespan:
- Local environment - especially temperature - extreme heat and cold are the enemies of a car battery
- Vibration - the more secure and well held-down a battery is, the fewer vibrations there are and the longer the battery will live
- Bad charging system - if your battery charging system is not working properly, there’s a chance it will go fully dead, and going completely dead and needing jump starting will shorten its lifespan, too.
How Often Should You Change a Car Battery?
It’s hard to put an exact lifespan on a battery, as we mentioned in the previous section. The best time to change your car battery is if and when the battery is showing signs of failure or serious damage (see below for more). On average, a battery is changed every between 3-5 years, so the mid-point there is 4 years.
However, it’s not a fixed rule. It’s not like at 4 years you should just definitely purchase and install a new car battery and dispose of the other one. The real lifespan of the battery depends on its quality, build, your driving habits, the climate you’re living in and more. It will have to be replaced sooner or later, but it’s less wasteful and more economical to do it at the right time instead of just following what could be an arbitrary timeline.
That being said, it’s equally not good for your car to leave the battery where it is right up to the point where it simply dies or seriously leaks (possibly acid) into your engine bay. Take 3 years as your first threshold to start your checks, 4 years as the time to become more closely vigilant, and 5 years as the likely maximum limit. Your mechanic should also advise you as to when the right time for changing will be. Ensure they always include it in their service checks.
Battery Change: Cost
How much does it cost to change a car battery? At the low end it can cost as little as $50, but it can range up to $250 or more for higher-quality or luxury-brand cars. Setting aside a budget of at least $120 is not a bad idea if you know that you’re going to need a new car battery sometime soon. That would cover many cars, but not for larger vehicles or luxury marques.
Signs That Your Car Battery is Failing
It’s important that you are aware of certain signs that your car battery might be close to failing. If the battery fails completely, or even a connected component like the alternator that recharges the battery while you are driving, then your car will be in serious trouble. Below are several signs to watch out for.
Sign 1: Engine Struggling to Start
All the wear and tear in your engine can lead to a slow or stuttering start, but the battery, but it’s a really serious problem when that is connected to the battery. When you turn your key or press your start button, the engine should instantly turn over and start its familiar hum. If it’s a slow and painful process, it’s typically a sign that the battery is on its last legs.
Before that, there may be other signs to look out for, which we will list below, but if you have experienced this recently, then it could be time to visit your mechanic for a new battery.
Sign 2: “Check Engine” Light
There are many warning lights on your dashboard, and one of the most common and feared is the “Check Engine” light. People fear the “Check Engine” light because they don’t know what it could mean and how serious the problem is. One of the problems could well be with your battery. If your dashboard actually has a dedicated battery warning light, then at least that will be clearer and you’ll know immediately what it is. If you have a “Check Engine” light in conjunction with other signs in this list, however, then it could well be the battery that’s letting the side down.
Sign 3: Corrosion
Do you know where your battery is in your car? In most cases, it’s in a very prominent position under the hood and is very easy to spot, but consult your owner’s manual if you’re not sure. When you’ve confirmed its location, take a closer look at the positive and negative connectors to see if there are any signs of corrosion. The terminals are on top of the battery and exposed to the air, so are susceptible to this kind of damage. Look for signs of any white, ash-like or powdery substance around the battery terminals. This is the corrosion that you hopefully won’t find.
Sign 4: Dim or Flickering Lights
When driving at night, do the headlights and full beams seem dimmer than usual? When you activate the dome light in your car’s interior, do you get a steady bright light or does it struggle at first, flickering on and off before settling on a duller-than-usual light?
Any kind of flickering, dimming or less than full performance from your lights anywhere on your car is a key sign that the battery is starting to fail. These are normally the systems that a working battery has no problem to keep working well. If it’s struggling with these, it’s struggling more fundamentally.
Sign 5: Struggling Electronics
On top of your lights, you might also find electrical inconsistency in your car’s stereo, infotainment display, device charging, and even the digital instrument cluster display (if you have one). Look out for any signs of electronics struggling in your car, especially if they’re struggling when you’re running at minimal power use.
Sign 6: Physical Damage to the Battery Case
While you’re inspecting the battery terminals for signs of corrosion, take a look at the casing, too. As the battery works in the hot conditions that exist under your hood in the engine bay, it can become misshapen and damaged. If you notice swelling, cracks, irregularities in its shape --- it’s normally quite perfectly cuboid --- then you could be looking at serious damage that could send it to its electronic grave.
Sign 7: Bad Odors
If that physical damage has become really serious, then your car battery could actually be leaking gas. This smell is extremely pungent and noticeable. It’s quite a lot like rotten eggs, so it certainly doesn’t fit in with any other smell in your car at all.
If you think you sense it in the passenger cabin, then the leak is very serious. Pop the hood and check if it’s coming from the battery. In most cases, such an odor should prompt you to get the car checked out, but seeing if it’s the battery or not first is still a useful idea.
Sign 8: It’s Been a While
As we discussed above, a car battery normally won’t last more than 5 years. That being so, if it has been a lot more than 5 years since you changed the battery, then it might just be coming to the end of its life. A good rule of thumb is to start being more vigilant about the battery health starting at the 3-year mark, because that’s the point from which other warning signs can start to appear.
Conclusion: It’s Never Worth Avoiding a Needed Battery Change
If you think it’s a good idea to simply squeeze every second you can from your car battery until it finally gives up altogether, then you’re being wrongheaded. It’s not “economical” to work the battery literally to death, especially when it can impact other parts of your car.
Look for the signs of damage, and be sure that your mechanic always follows the maintenance schedule when checking your car each year.
The battery is simply one of those components on which you don’t want to “cheap out.”