A car battery is one of the most essential components of your vehicle, providing the necessary power to start the engine and run electrical systems. However, like all parts, it has a limited lifespan and will eventually need replacing. Recognising the signs of a failing battery can help you avoid unexpected breakdowns and ensure your vehicle remains reliable. This guide will help you understand when you should replace your car's battery and the key signs to look out for.
How long does a car battery last?
Typically, a car battery lasts between 3 to 5 years, but several factors can affect its lifespan, including:
- Driving habits – frequent short trips don’t allow the battery to fully recharge, leading to a shorter lifespan. Leaving the key in the ignition without turning the engine on can also drain the battery to the point you may have to jump start it.
- Weather conditions – extreme heat or cold can affect battery performance and longevity.
- Electrical load – using high-powered accessories like heated seats, advanced infotainment systems, or external charging devices can drain the battery faster.
- Maintenance and care – regular battery checks and keeping terminals clean can prolong its life. It’s always advised that you book your car in for a service or MOT to check that all of the components in your car are working well.
Signs that your car battery needs replacing
If you’re battery needs replacing, there are some tell-tale signs that you should be on the lookout for:
Slow Engine Crank
One of the first warning signs of a failing battery is a slow or sluggish engine crank. If your engine takes longer than usual to start, it could mean your battery is struggling to provide enough power and it’ll need replacing.
Dashboard warning light
Most modern cars have a battery warning light on the dashboard. If this light comes on, it indicates an issue with your charging system, which could mean the battery is not charging properly or there is a problem with the alternator.
Dashboard warning light
Most modern cars have a battery warning light on the dashboard. If this light comes on, it indicates an issue with your charging system, which could mean the battery is not charging properly or there is a problem with the alternator.
Dimming headlights and electrical issues
A weak battery may struggle to power your vehicle's electrical components. If you notice:
- Dim headlights or flickering interior lights.
- Power windows operating slower than usual.
- Radio or infotainment system acting erratically.
It’s a good indication that your battery is losing power.
Frequent jump starts needed
If your car frequently needs a jump-start, this is a clear sign that the battery is failing. While jump-starting can be a temporary fix, a battery that requires frequent boosts is likely near the end of its lifespan.
Corrosion on battery terminals
Check your battery terminals for white, ashy deposits or corrosion. Excessive corrosion can affect the battery’s ability to charge and deliver power efficiently. Cleaning the terminals can sometimes help, but persistent buildup may indicate a failing battery.
Swollen or bloated battery case
Extreme temperatures can cause the battery case to swell or become deformed. If you notice that your battery appears bloated, it’s a sign that it has overheated and should be replaced immediately.
Unusual smells from the battery
A leaking battery can emit a strong, rotten egg smell caused by sulfuric acid leakage. This is a serious issue and requires immediate attention, as it can damage surrounding components and pose safety risks.
Old age
Even if your battery isn’t showing obvious signs of failure, if it’s more than three to five years old, it’s worth getting it tested. A professional battery test can help determine whether it’s still holding a charge properly.
How to test your car battery
If you’re unsure about your battery’s condition, here are a few ways to test it:
Use a multimeter
A multimeter can measure your battery’s voltage. A fully charged battery should read around 12.6 volts when the car is off and around 13.7 to 14.7 volts when the engine is running.
Get a professional battery test
Most garages and auto parts stores offer free battery testing. They use specialised equipment to check the battery’s charge, voltage and overall health.
Perform a headlight test
Turn on your headlights before starting the engine. If they appear dim and then brighten after starting the car, your battery may be weak and struggling to supply power.
What to do if your battery needs replacing
If you’ve determined that your battery needs replacement, follow these steps:
Choose the right battery
Refer to your vehicle’s manual or consult a professional to ensure you purchase the correct size and type of battery. Consider factors such as:
- Cold Cranking Amps (CCA) – these are important for colder climates to ensure reliable starts.
- Reserve Capacity (RC) – measures how long the battery can run essential functions if the alternator fails.
- Brand and warranty – opt for a reputable brand with a good warranty for reliability.
Install the New Battery
If you’re comfortable with DIY car maintenance, you can replace the battery yourself by:
- Turning off the engine and disconnecting the negative (-) terminal first.
- Removing the old battery and cleaning the terminals.
- Installing the new battery, connecting the positive (+) terminal first.
- Ensuring all connections are tight and secure.
Alternatively, many garages and auto shops can replace the battery for you in minutes.
Dispose of the old battery properly
Car batteries contain harmful chemicals and should not be thrown in regular waste bins. Take the old battery to a recycling centre or return it to the auto shop where you purchased the new one for proper disposal.
Servicing and MOTs from Swansway
A failing car battery can cause inconvenience and unexpected breakdowns, but recognising the warning signs early can help you avoid being stranded. Regular maintenance, proper care and timely replacement ensure that your vehicle stays reliable. If your battery is over three years old or showing symptoms of failure, get it tested and replace it if necessary. By staying proactive, you can keep your car running smoothly and prevent unwanted disruptions. At Swansway, we conduct servicing and MOTs to ensure your vehicle is in optimal health to keep you safe and on the move. If you think there’s something wrong with your battery, contact us today and we can help resolve the issue.