When to Replace Your Car Battery and Cost

Car ownership can come with a variety of different challenges, and many drivers will encounter problems with their battery at some point. 

It can be hugely frustrating to get into your car and turn the ignition only for nothing to happen. However, having at least a basic understanding of what the problem might be can be extremely beneficial when it comes to getting back on the road as quickly as possible.  

What is a car battery? 

Like many things we use today, our vehicles rely on a battery to function. Car batteries are rechargeable energy storage devices that deliver electrical power to a variety of different systems and components within a vehicle. 

Car batteries are most commonly positioned in the engine compartment and supply the electricity required to start the vehicle and power some of the core electrical systems where the alternator's capacity isn't large enough to handle spikes in the electrical loads required or when the engine is not on. 

So, car batteries are specifically designed to provide a high electrical current for a brief period of time, which is how it is able to turn over the starter motor. Additionally, they are optimised to provide a vehicle's electrical system with a steady flow of power and to contribute to the voltage stabilisation necessary to ensure systems continue to operate properly. 

What do car batteries look like? 

Most cars are equipped with a 12-volt battery, however, vehicles that are larger than average or are equipped with features that require more power may have a higher voltage battery. 

Generally, most car batteries are lead-acid based, which means that an electrolyte and sulphuric acid solution is contained within a plastic case. Lead plates are also present within the plastic case, and it is the chemical reaction that takes place between the plates and the solution that creates electrical energy.  

How is a battery charged? 

When the car is in use, the alternator works to recharge the battery using energy from the engine. It is important to ensure that checking the battery forms part of your car maintenance routine, as corrosion on the battery terminals or poor electrical connections can negatively impact the overall performance and longevity of the battery. 

How long do car batteries last?  

There are a number of different factors that can affect the lifespan of a car battery, including the climate you drive in, the driving conditions you experience, and how well the vehicle is maintained. The build quality of the battery and the quality of its original installation can also play a role. Generally speaking, it is reasonable to expect that a new battery in a diesel or petrol car will last for between three and five years. Electric vehicle Lithium Ion batteries are designed to last longer and are significantly larger, so drivers of electric cars can reasonably expect a new battery to last for at least 10 years or for 100,000 usage miles. Note that many EVs also utilise a traditional lead acid battery to run auxiliary systems. 

Batteries degrade with use over time, which can affect their ability to hold a charge. In this situation, it is beneficial to have the battery replaced. 

What are some common signs that my car is experiencing battery problems? 

There are a number of different signs that can signify that your vehicle would benefit from a new battery.  

If you notice that the battery case is misshapen or looks bloated, it is important to have the battery replaced as soon as possible. Similarly, corrosion to the battery terminals can significantly affect its overall performance. In some cases, corrosion or build-up can be removed, however, after discussing your options with a vehicle professionals, you may decide that replacing the battery is the best course of action. 

Weakened batteries can often lead to dim headlights, which can be dangerous, particularly when driving at night. You may also experience problems with other electrical components within your vehicle, including dim interior lights.  

If it frequently takes more than one attempt to start your vehicle, it is likely that your battery is starting to weaken and needs to be replaced. Similarly, the overall age of your car's battery should also be taken into consideration. We recommend speaking to our qualified fitters at your local Protyre garage regarding the current health of your battery during your next annual service. 

How do I change a car battery? 

If you're here after searching "changing car battery" online, here is our brief step-by-step guide to completing each stage safely. 

IMPORTANT: WHILST THE VOLTAGE MAY BE LOW, THE HIGH CURRENT FROM A CAR BATTERY CAN BE LETHAL. ALWAYS EXERCISE CAUTION. 

Step 1: Removing a car battery 

1. Turn the car engine off and remove the keys from the ignition. Put on gloves and safety goggles to ensure you are protected from accidental contact with battery acid. 

2. Look in the engine compartment for the battery or consult your owner's manual.  

3. Loosen the bolt or nut that is securing the negative terminal, which will be marked with "Neg" or "-" symbol. 

4. When the bolt is loose, carefully twist the cable and pull it away from the terminal, taking care not to let it touch any metal parts. 

5. Loosen the bolt or nut securing the positive terminal, which will be marked with "Pos" or "+" symbol. 

6. Carefully twist the cable to remove it from the terminal, again ensuring that it doesn't touch any metal parts.  

7. Some batteries are held in place by a hold-down bracket. Loosen any bolts as required. 

8. Remove the battery from the tray by carefully lifting it directly upwards. Do not tip the battery, as you may spill some acid. Remember, car batteries are heavy, so proceed with caution and ask for help if required. 

9. Clean the battery tray using water and baking soda to remove all traces of residue or corrosion.  

10. Dispose of the battery safely at an automotive garage or recycling centre. 

Step 2: Reconnecting a car battery 

1. Position the new battery in the battery tray.   

2. Locate the positive battery terminal, which will be marked with a "Pos" or "+" symbol. 

3. Align the positive cable, which is generally red, with the positive battery terminal. 

4. Slide the cable into place and tighten the bolt or nut. It should be secure but not overly tight. 

5. Repeat the above steps with the negative cable, which is generally black.  

6. Ensure both connections are firmly in place. The cables should not come loose easily. 

7. Check for signs of corrosion on the battery terminals and clean if necessary.  

8. Test your vehicle's electrical systems, including your headlights and radio system. 

How much does a car battery cost? 

When it comes to changing your car, battery cost is always going to be a factor. Prices do vary, however, costs start at around £80 and range to over £400 depending on the vehicle and battery type.  

It is generally best to replace your car battery when it starts showing signs of deterioration to avoid total failure. This can help to avoid inconvenience, call-out and recovery charges. However, it is always worth checking with your local Protyre garage before making any decisions. 

Our tyre professionals and mechanics regularly work with tyres from all the top brands, including Pirelli and Bridgestone, and have a wealth of experience working on vehicles from an array of motoring manufacturers. Why not book your free vehicle check online today or contact your local Protyre for a service to ensure you're getting the optimal performance from your car. 

Our experts will assess if your battery needs replacement. We also offer aircon, brakes, suspension, steering, exhaust, and tyre checks - providing complete peace of mind. 

When it's time to replace your battery, rest assured our trained mechanics will get you back on the road. We also make buying new tyres online easy and convenient with our simple process, quick quotes, and national fitting network of over 180 Protyre garages.  

Rely on Protyre for all your car maintenance and tyre needs.