In need of a new car battery? Don't worry, this guide can show you what's what when it comes to watts!

If your car won't start, then there may be a problem with your car battery. This crucial component is responsible for a lot of functions within your car, so you'll need to keep your car battery in good shape. Our buyer's guide will not only help you to find a replacement battery if yours has reached the end of its life, but also help you to make your current battery last as long as possible!

If you already know all about car batteries and just need to see which one your car needs, then use our handy car battery lookup tool.

What is a car battery?

Essentially, a car battery is just a big rechargeable battery that provides your car with electricity used for various jobs. It's a plastic box, sometimes with a coloured top and two connection points called terminals where the battery connects to your car's electrical system. You'll also see a sticker on the side which shows a bit of jargon (more on that later), manufacturer information and most importantly a sticker with the number of years the battery is covered under its guarantee.

Why does a car battery do?

Car batteries aren't an optional extra - they do a few critical jobs within the car and you'd be left at a standstill without one!

Starting - when you put your key in the ignition and give it that first half-turn to wake it up, your car battery is making that possible. You can run your air vents, turn on the interior lights, check the dashboard lights or listen to the radio without having to the turn the engine on thanks to your battery. Be careful if you do any of this for an extended period of time without the engine running, as you'll soon run out of charge!

Lighting - your interior lights, indicators and of course rear and main headlights run straight off the battery. This means you can still see (and be seen) while parked up with the engine switched off. Alongside the lights, car batteries also power the other electrical items you can fit to your car or plug into the 12V power outlet, including Sat-Navs, phone chargers, DVD players and even mini fridges for those camping trips!

Ignition - car engines don't just start themselves and require electricity to get going. Batteries provide the electricity to the spark plugs or heating elements, the bits that light the fuel in your engine and make it run.

How do car batteries work?

Just like normal batteries, car batteries use a chemical reaction to generate the electricity needed to run the lights or start the engine. When the key is half-turned in the ignition, the chemical reaction takes place, with electricity released to the car's systems to the battery. Over time, the battery will lose its charge, but luckily the reaction can be reversed, allowing energy to be stored in the battery ready for the next time the engine needs to be started. This is known as 'charging' the battery.

How do I charge my battery?

If your battery is totally flat and the engine won't turn over, then you'll need to use a charger to give it a full charge. You'll need a charger that's fully compatible with your car and battery and you'll need to follow a few rules to prevent damage to either the battery or the charger - which you can find in our How To Charge a Car Battery guide.

What are the different kinds of car battery?

Halfords currently supplies three main types of car battery, which we'll get to shortly. How long they last really depends on how often you turn your engine on and off, how far you drive each year and other factors such as letting your battery run down repeatedly. Certain types of battery will last longer than others, but the key thing to look out for is the number of starts and if there is a guarantee.

How long do car batteries last?

Depending on the type of battery your car has, there'll be a number of starts that your battery will be able to provide before it begins to wear out or refuses to charge. Here's more information on the batteries we sell and rough breakdown of how long each will last.

Lead Acid

Lead acid batteries are one of the most common types found in vehicles. Durable and relatively cheap to replace, these 20,000 start batteries will last a long time before they'll need to be replaced, plus they're covered by a 3 year guarantee.

Shop our lead acid batteries

Calcium

These batteries offer a slight improvement on lead acid batteries thanks to their 4 year guarantee and a rating for around 30,000 starts. You'll also get 18% more starting power, which is handy on colder mornings when engines often need an extra kick to get going.

Shop calcium batteries

Yuasa Silver

Our top end calcium batteries come with a 5 year guarantee and are good for up to 50,000 starts. You'll also get an additional 33% starting power than you would with an ordinary battery.

Shop Yuasa silver batteries

If your car has start / stop technology (the engine switches off when you stop at traffic lights or junctions), then you'll need a different AGM or EFB battery. These batteries are a bit more expensive, but are a lot more durable, lasting for an incredible 360,000 starts! These special batteries may need to be registered with your car's on-board computer to work properly, so we'd recommend having them replaced by our in-store professional to make sure your start / stop function continues to work.

Shop start / stop batteries

Why do car batteries have a guarantee?

At Halfords, the batteries we provide come with 3 year, 4 year, 5 year or lifetime guarantees (the lifetime of the battery, not the car or owner!). This doesn't refer to how long the battery will last, but for how long you'll be covered if there's a manufacturing fault with the engine. If you think your battery isn't working as it should and is within the guarantee period, then check out this guide.

How do I install a new car battery?

When it comes to replacing your old car battery, we'd recommend getting a Halfords professional to do it for you. Both batteries and electrical systems can get easily damaged if the battery isn't hooked up correctly or live cables touch metal parts of the engine bay, plus sparks created when terminals and connection cables touch can be a serious fire hazard. If you buy a car battery from Halfords, we'll be more than happy to install it for you for a small charge.

Which car battery brand is best?

Lots of recognised brand names can be found in the world of car batteries, including Bosch, Yuasa, and even our Halfords own-brand batteries, but realistically you should be looking out for the cold cranking amps (how much power is provided to get the car started) and the amp hours (how long the battery will last before running out), as well as what kind of battery you're buying - lead acid batteries aren't as powerful or long-lasting as Yuasa silver batteries for example.

How do I know if my battery needs replacing?

There are a few tell-tale signs that your battery could be on its way out. If your car engine is struggling to turn over even on milder days, then your old battery may not be able to provide the same cold cranking power as it did when it was new. You may also see a battery light on the dashboard that indicates if there's something wrong. If your car battery goes flat just a few days after a full charge, or runs out of juice even with just the interior or parking lights switched on, then it's probably time for a replacement.

It's worth noting that car electrical systems aren't always caused by the battery and the alternator may actually be the culprit. If you book a free battery check or service at Halfords, we'll be able to tell you straight away if your electrical or starting problems are more complex than a dead battery.

How to recycle a car battery

Car batteries contain lots of nasty ingredients that mean they can't be put into your normal household bin or recycling bin, but the good news is we'll do it for you! If you have your new battery fitted by Halfords, we'll dispose of your old one for free.

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