Your car’s battery is one of its most important components. Without it, you wouldn’t get far; the engine couldn’t start - and the electrical systems would have no power.
You might think the battery doesn’t need any attention until it goes flat. However, the reality is, a poorly maintained or faulty battery can negatively impact your car’s performance way before that stage.
A flat or faulty battery can cause your car to fail its MOT and reduce its market value. Therefore, your car battery shouldn’t be an afterthought, especially if you’re wondering if you should sell your car.
In this guide, we’ll cover the causes and telltale signs of battery failure. We’ll also break down the costs of car battery replacement, and the steps for installing a car battery at home. Finally, we’ll share a few helpful tips for extending battery life.
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Common causes of battery failure
Car batteries aren’t meant to last forever. In fact, most will only last three to five years. However, various factors will cause some batteries to fail more quickly than others.
One of the most common reasons for battery failure is power drain. Accidentally leaving your headlights on overnight is an obvious cause. However, you might not realise that using the radio, interior lights, and air conditioning with the engine switched off will also drain the battery.
Other power-sapping habits include only driving short distances (which prevents the battery from fully charging), not driving often enough - and leaving your car exposed to extreme temperatures.
Loose battery cables can be an issue, as can grime buildup on the terminals, so check for both regularly. Finally, a faulty alternator will negatively affect the battery’s health, so make sure yours is working correctly.
Signs of car battery failure
Other than the car battery dashboard warning light, there are several telltale signs which indicate battery failure:
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The engine takes longer than usual to fully start, or it takes several attempts to start it at all.
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Your car stalls more often than it should.
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Your battery goes flat quickly after recharging.
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Interior and exterior lights dim or flicker.
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The windows, air conditioning, infotainment system, and other electric power-driven features stop working properly.
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If you look at the battery itself, you might notice that the casing is swollen, the terminals are corroded, or there’s a leak (usually accompanied by a bad smell).
Be vigilant, and if you spot any of these signs, it may be time to replace your car battery.
What factors influence car battery replacement costs?
The cost of car battery replacement largely depends on the type of battery you need.
There are three main types of car battery: the standard lead-acid batteries (at the cheaper end of the market), along with absorbent glass material (AGM), and enhanced flooded batteries (EFB), which both tend to be pricier.
Let’s take a look at some of the major factors that influence car battery replacement costs:
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Battery costs can vary considerably between different car makes and models. For example, a luxury or modern vehicle will need a higher-end battery capable of powering all those extra features, whilst a lead-acid battery will probably get the job done for a basic older motor.
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As with any consumer product, you’ll pay more for brand names. You may decide that the higher price tag is worth it for your peace of mind.
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It’s also important to consider labour costs (unless you can confidently install the battery yourself). Where you choose to get your new battery fitted will also affect the overall cost: high street chains are usually cheaper than independent mechanics and dealerships.
With all these factors impacting the cost of replacing your car battery, it’s well worth shopping around to get the best deal.
Typical battery replacement costs:
Lead-acid battery: £60-£120
EFB battery: £100-£160
AGM battery: £150-£250
Where should I get my replacement battery from?
Dealerships:
You may also benefit from an extended warranty. However, bear in mind that dealerships are the most expensive option for both batteries and installation. The range of batteries on offer may also be smaller than at parts retailers.
Car parts retailers: High street retailers generally have a wide range of batteries for sale - and some even offer free installation. Independent shops don’t always have the same range, so you might have to either shop around, or wait for your battery to be ordered in.
Prices tend to be lower than at dealerships, but you might find that the staff aren’t quite as knowledgeable or experienced.
Online retailers: You’ll find a wide range of competitively priced batteries at online retailers. This is also the most convenient way to shop, as you’ll get the battery delivered straight to your door.
However, installation is not included and, if you’re inexperienced, you’ll also run the risk of ordering the wrong battery for your car.
DIY replacement: With no installation costs, this is the cheapest option. It’s also convenient, as you can replace your battery whenever it suits you.
However, there are some risks to contend with if you don’t know what you’re doing. You could damage your car, your battery, or injure yourself if you make a mistake during installation.
We’ll cover how to safely install a car battery later in this guide.
What battery do I need for my car?
Car batteries come in different sizes and configurations, so you’ll need to order one that fits into your car’s engine, with the terminals facing the right way to connect.
Batteries also have differing capacities, which are measured in two ways:
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Amp hours (Ah), which denotes how long the battery will last before it needs recharging.
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Cold cranking amps (CCA), which denotes how much power is needed to start the car in cold conditions.
Still unsure whether a specific battery is suitable for your car? You can check by:
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Referring to the owner’s manual.
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Using an online battery checker. These tools allow you to input your car’s make, model and year to find a compatible battery.
How to replace your own car battery (step-by-step)
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Park your car on a flat surface, turn the engine off, and make sure the parking brake is on. Remove the keys.
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Put on safety gloves and goggles to protect you from any corrosive liquids.
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Open the bonnet and find the battery, then identify the positive (red/+) and negative (black/-) terminals.
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Loosen the nut on the negative terminal, then remove the cable. Don’t let the wrench touch the positive terminal or any other metal parts.
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Remove the cable from the positive terminal using the same process as above.
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Lift the battery out of its tray. (You may need to unclip or undo a bracket or clamp.)
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Clean the tray with a wire brush.
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Put the new battery in, making sure the positive and negative terminals are facing the right way. Reattach any clamps or brackets.
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Connect the cables, but in the opposite order. In other words, connect the positive cable first, then the negative. Make sure you tighten the nuts carefully.
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Close the bonnet and try starting the car. If the engine starts up smoothly, you’ve successfully replaced your car battery!
Tips for extending car battery life
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If you don’t plan to use your car for an extended period, you can disconnect the battery altogether.
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Want to keep the battery in? Use a trickle charger to keep it fully charged.
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Making a mix of regular and long-distance journeys will help to keep the battery charged.
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Get your battery professionally checked every now and again.
What about EV car batteries?
Most EVs use lithium-ion batteries that are designed to last for many years. These vary widely in capacity but typically allow vehicles to travel between 150 and 400 miles on a single charge.
EV charging times vary too, with slower home chargers taking up to 12 hours. Most public chargers are considerably quicker - and some rapid chargers can charge to 80% within an hour or less!
Disposing of car batteries
As car batteries contain hazardous materials, you can’t just throw them out with your regular rubbish. Luckily, you can take them to certified recycling centres and many car part retailers, although some will charge you a small fee.