Guide to car batteries

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Ever wondered about the mechanics of a car battery? Curious about its lifespan? Interested in learning ways to prolong its life?

Dive into our comprehensive guide to car batteries and discover what steps to take if yours fails.

What is a car battery?

The car battery is a vital component that acts as the heart of your vehicle’s electrical system. It is a rechargeable unit that provides the necessary electrical energy to start the engine.

When you turn the ignition key or press the start button, the battery delivers power to the starter motor, which then cranks the engine. Once the engine is running, it relies on the battery to generate a spark for the spark plugs, igniting the air-fuel mixture in the engine’s cylinders, thereby initiating the combustion process.

Beyond just starting the engine, the battery plays a key role when the vehicle is idle or in accessory mode. It supplies energy to essential features like the radio, lights, air conditioning, electric windows, and the vehicle’s onboard computer system.

However, car batteries have a finite lifespan and can become depleted. A significant cause of battery failures is draining it by leaving electrical components, like lights, on when the engine isn’t operating.

Such a mistake can be particularly common among new drivers or in vehicles without automatic light shutoff features. Regular maintenance and checks can help ensure the battery’s optimal performance and extend its lifespan.

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How do car batteries work?

Delving just a bit into the mechanics without overwhelming with science, car batteries are similar to energy reservoirs.

They harness and store chemical energy, which, when needed, transforms into electrical energy to bring the car’s engine to life.

The lion’s share of car batteries are of the lead-acid type. This means they house lead plates that are submerged in an electrolytic solution made of sulphuric acid and water.

Initiating the ignition process – like turning the key – sparks off a chemical interplay between the lead and the acid. This interaction churns out an electrical surge potent enough to crank up the engine and initiate the combustion process.

As you cruise on the road, the car’s alternator, powered by the running engine and connected through a belt, takes on the role of an electrical generator. It not only fuels the myriad electrical components in your car – think lights, music system, and air conditioning – but also serves a dual purpose.

A portion of the electricity generated by the alternator is channelled back to the battery. In the battery, the electrical energy undergoes a reverse chemical transformation and is stored anew as chemical energy, ensuring your battery remains charged and ready for the next start.

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How much are car batteries in the UK?

The cost of a car battery in the UK hinges on several factors: the type and size you require, its quality, the kind of warranty it comes with, and the retailer or source you choose to purchase it from.

Prices for car batteries in the UK can span a broad spectrum. Depending on your vehicle and needs, you could spend anywhere from £45 up to £330 for a replacement. One thing to note is that stop/start batteries, which are designed to accommodate cars with start-stop technology, tend to be more expensive.

However, the costs don’t stop at just buying the battery. If you’re not confident in your DIY skills or don’t have the necessary tools, you’ll need to consider the expenses associated with getting it fitted.

While some high street chains offer battery installation at competitive prices, often starting from around £20, opting for a dealership or specialist might increase the cost. So, it’s wise to shop around not just for the battery itself, but also for the best fitting price, ensuring you get the most value for your money.

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Can I change a car battery myself?

Trying to replace your own car battery can be a risky endeavour. Firstly, selecting the appropriate battery for your vehicle requires a good deal of knowledge and understanding. An incorrect choice might not just be a mismatch but could potentially harm your car’s intricate electrical system.

Mistakes during the replacement process can lead to hazards, both to the individual and the vehicle. It might also result in costly repairs down the line.

Furthermore, while you might suspect the battery to be the root of the issue, it’s not always straightforward. There could be underlying problems with the vehicle that aren’t immediately visible to an untrained eye.

Only a professional mechanic, with their extensive training and experience, can accurately diagnose if the issue lies with the battery or another part of the car.

Therefore, for peace of mind and to ensure the longevity of your vehicle, it might be best to leave such tasks to the experts.

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How long do car batteries last?

Under ideal conditions, with the correct choice of battery tailored to your vehicle’s specifications and proper maintenance, you can expect a car battery to serve you well for about three to five years, though some might even surpass this average lifespan.

The longevity of car batteries is influenced by driving habits. Consistent longer drives are beneficial for your battery; they allow it to achieve a full charge, courtesy of the engine’s continuous operation which keeps replenishing the battery’s charge.

Additionally, frequently taking short journeys can have the opposite effect, potentially reducing your battery’s lifespan, as it may not get the adequate charge it requires.

Another point to consider is the natural discharge rate of batteries. A car battery, even when not in use, will gradually lose its charge. Consequently, if your car remains stationary for extended periods, it can lead to premature battery wear.

Additionally, external factors like extreme temperatures, especially excessive heat, can impact battery health. Thus, it’s crucial to be aware of these influencing factors and take measures like periodic checks and ensuring optimal storage conditions to maximise your car battery’s life.

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How do I know if I need to replace my car battery?

Recognising when your car battery is nearing its end can save you from unexpected breakdowns. Here are several indicators that suggest it might be time for a new battery:

Delayed Engine Start: One of the most common signs is when your car takes longer than usual to start. As a battery ages, internal components can corrode, diminishing its efficiency and capability to deliver a strong initial spark.
The Electrics Don’t Work: If you find that the lights, radio, or other electrical systems are not functioning properly or are weaker than usual, it could be due to the battery not supplying adequate power as it nears the end of its operational life.
Warning Lights on Dashboard: If the battery or engine warning light illuminates on your dashboard, it’s a clear indication that something isn’t right. It’s advisable to get your car inspected and the battery tested promptly when this occurs.
Unpleasant Odours: An unusual, sulphurous or rotten egg smell emanating from under the bonnet could be a sign of a battery leak, leading to the emission of hydrogen sulphide. This not only indicates battery damage but can also be harmful, so it’s crucial to have the battery assessed immediately.

Physical inspections can be helpful. Check for any visible signs of corrosion on the battery terminals or any bloating in the battery case. Both are indicators of potential issues.

Remember, even if your car doesn’t show these signs, it’s good practice to have your battery checked periodically, especially if it’s been in use for several years.

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How do I avoid running down my car battery?

To extend the life and maintain the health of your car battery, consider the following recommendations:

Limit Accessory Usage: Avoid using electronic accessories like the radio, air conditioner, or lights excessively when the engine is not running. These can sap the battery’s power without the engine on to recharge it.
Inspect Regularly: Periodically examine your battery. Look out for any loose cables, corrosion, or accumulated debris on the terminals. While those familiar with cars might handle minor issues independently, it’s often advisable to consult with a professional mechanic for a thorough evaluation and cleaning.
Mind Your Driving Patterns: Frequent short trips don’t allow the battery to charge fully, leading to a reduced lifespan. Whenever possible, intersperse these short drives with longer rides, which can help maintain the battery’s health.
Drive Consistently: Ensure you drive your car periodically. Regular drives enable the alternator to recharge the battery adequately.
Consider a Trickle Charger: If your vehicle remains stationary for extended periods, a trickle charger can help maintain a stable charge, preventing the battery from discharging entirely.
Be Vigilant about Electronics: After parking, double-check that you’ve switched off internal lights, headlights, and any plug-in accessories like dash cams or phone chargers, as these can continue drawing power and drain the battery.
Mind the Parking Spot: Wherever possible, park your vehicle in a garage or at least in a shaded area. Batteries can be sensitive to extreme temperatures, with both scorching heat and freezing cold potentially impacting their efficiency and lifespan. Protecting your car from such extremes can certainly be beneficial for the battery.

By taking these steps and being proactive in battery care, you can enhance its longevity and performance, potentially saving yourself both time and money in the long run.

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How to fix a dead car battery

Before resorting to replacement, there are a few steps you can attempt to breathe life back into a drained car battery:

Charging Using a Battery Charger: If the battery isn’t entirely dead, you can try rejuvenating it with a car battery charger. These chargers are typically easy to use and plug directly into a standard electrical outlet. Ensure you follow the manufacturer’s instructions closely when using a charger.
Jump-Starting the Car: If the battery has drained completely, jump-starting can be a feasible solution. To do this, you’ll require a set of jump leads and a second vehicle with a working battery. After securing the jump leads properly to both batteries (connecting positive to positive and negative to ground), start the working car’s engine, and after a few minutes, attempt to start the dead car. If successful, let the once-dead car run or drive it for around 30 minutes to give the alternator enough time to recharge the battery.

Learn how to jump-start a car
Seek Professional Assistance: If neither charging nor jump-starting resurrects your battery, the issue may be deeper or the battery may be irreversibly damaged. In such cases, consulting a mechanic is advisable. They can perform a comprehensive diagnosis, address any underlying issues, or recommend a battery replacement if necessary.
Use Breakdown Services: If you’re enrolled in a breakdown cover or roadside assistance service, it’s worth reaching out to them. Not only can they help diagnose the issue on the spot, but many services also carry replacement batteries and can switch them out for you immediately if required.

Breakdown cover providers

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AA breakdown cover

Related: Does Second Car Insurance Exist?

RAC breakdown cover

Related: Classic Car MOT

Lastly, remember that frequent battery drains can signal either a problematic battery or issues elsewhere in the car’s electrical system. If you find yourself repeatedly facing dead batteries, a more thorough inspection might be in order.

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Why has my car battery died?

Car batteries, though robust, can run out of charge or face issues for a variety of reasons:

Infrequent Use of the Car: If a vehicle remains stationary for extended periods, the battery may naturally discharge. Consistent use ensures the alternator keeps recharging the battery, maintaining its health.
Electrical Accessories Left On: It’s quite common to forget turning off the lights, radio, heater, or even the indicators. When left on without the engine running, these accessories can drain the battery over time.
Faulty Alternator: The alternator plays a crucial role in maintaining the battery’s charge while driving. If it malfunctions, it might not provide the necessary charge to the battery, leading to eventual depletion. Warning signs of a problematic alternator include flickering dashboard lights or unusual noises from the engine area.
Old or Deteriorating Battery: Like all components, batteries have a lifespan, often around five years or so. If your battery has been in use for several years and has not been maintained well, it might naturally be nearing its end.
Other Electrical Faults: It’s crucial to note that not all start-up problems point to the battery. If, for instance, you can switch on the headlights and they appear bright, the issue might lie elsewhere in the electrical system.

If you face difficulties in starting your car, a simple first step is to check its lights. Bright lights often suggest the battery has enough charge, implying that the issue could be with another electrical component.

In such cases, or if you’re unsure about the nature of the problem, it’s prudent to reach out to a mechanic or your local garage for a professional diagnosis.

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How to dispose of car batteries

Discarding car batteries with regular trash is not only environmentally unfriendly but can also be hazardous due to the harmful chemicals they contain, including lead dioxide and sulphuric acid.

These substances pose significant threats to the environment if not handled appropriately. Here’s how you can ensure their proper disposal:

Return to the Seller or Mechanic: Often, when you purchase a new battery, the seller or mechanic will have a system in place to take back the old one for proper disposal or recycling. It’s worth inquiring about this service when buying or replacing a battery.
Local Recycling Centre: Many local recycling facilities accept car batteries because they are designed to handle and process hazardous materials. Make sure you handle the battery with care, using gloves, when transporting it to prevent any acid leaks or exposure.
Battery Buy-back Programs: Some manufacturers or retailers offer battery buy-back or exchange programs, providing incentives for consumers to return used batteries for recycling.
Hazardous Waste Collection Events: Some municipalities hold periodic hazardous waste collection events where residents can safely dispose of materials, including car batteries.
Contact Auto Parts Stores: Many auto parts retailers provide battery recycling services. It’s a good idea to give them a call and see if they accept old batteries.

Remember, proper disposal of car batteries not only ensures environmental safety but also helps in the recovery of valuable materials like lead, which can be recycled and used in the production of new batteries.

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Frequently asked questions

What is the right size battery for my car?

To identify the appropriate battery for your car, consult your vehicle’s owner’s manual. Within it, there should be a dedicated section discussing the battery or instructions for battery replacement. This information might also be found under sections like technical details or specifications.

Typically, battery sizes are represented using a code, which could be a combination of two or three letters and numbers. Selecting the correct battery size ensures that the battery will not only fit perfectly into its designated compartment but also that its terminals align correctly.

If your manual is unavailable, you can usually find the size indicated on the battery itself. As an additional resource, many retailers that specialize in batteries offer search functions, allowing you to input your car’s make, model, or even its registration number to pinpoint the right battery size.

How long does it take to charge a car battery?

The duration required to charge a car battery can differ based on the specific make and model of your vehicle and the efficiency of your charger.

For those pressed for time, charging can be achieved in roughly two to four hours. However, for optimal battery health, a more gradual overnight charge is recommended.

After jump-starting your vehicle, a drive of about thirty minutes should suffice to recharge the battery to a functional state.

How to start a car with a dead battery

Should your vehicle fail to start due to a dead battery, the most straightforward remedy is a jump-start.

To execute a jump-start, you’ll require jump leads and another vehicle that has a fully charged battery. For a detailed walkthrough and crucial safety tips, refer to our comprehensive guide on jump-starting vehicles.

Can a car run without a battery?

While theoretically a car might function using just the alternator to supply power to the engine, initiating the car’s start would be impossible without a battery.

What does it mean if my car’s dashboard battery light is on?

When the battery symbol lights up on your car’s dashboard, it doesn’t always imply a failing battery. The cause might be an electrical glitch or an issue with the charging mechanism. Regardless, it’s wise to consult a mechanic and have it examined.

How does the weather affect my car battery?

Cold weather can strain your car battery since it has to exert more effort to maintain both the vehicle and its occupants warm. This is especially noticeable in electric vehicles, where battery life diminishes more rapidly during winter compared to summer.

Conversely, during hot seasons, excessive heat can prompt essential fluids within the battery to evaporate. This can result in corrosion and potentially cause the battery to malfunction.