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How to Fit a New Car Battery

a car battery

A flat battery could not only make you late for work, it could stop you getting anywhere for hours or even leave you stranded in the middle of nowhere. 

Like most car parts, batteries need replacing occasionally. Often, the reason a car battery fails is because it is simply too old and no longer up to the job it was designed for. If this is the case, then unfortunately continuous jump-starting or recharging will not solve the problem.

As a guide, the life of a regular car battery is usually somewhere between three and five years when properly cared for, but even this is dependant on several important factors.

Why do car batteries go flat?

A battery will lose its charge and become flat if it is not used regularly, or if the car is used for short journeys only when the battery will not have enough time to recharge itself properly. The term for this is ‘under charging’. This leads to a hardening of the lead plates within the battery that affects its ability to hold a charge, known as ‘sulphation’.
As a car battery works on a chemical reaction basis, the environment temperature and humidity can also play a crucial role in battery performance. A battery operates at maximum efficiency at a temperature of 26.7℃. Higher temperatures speed up internal corrosion within the battery’s cells, which reduces the life of the battery. Colder temperatures inhibit a battery’s ability to provide sufficient power to start and run a vehicle.
Even leaving an interior light on accidentally can be enough to run your battery flat if left on for long enough.

How to tell if your battery needs replacing

There is a simple test you can carry out to determine the condition of your battery. First, try starting your car at night with the headlights switched on. If the headlights are overly dim, put the vehicle in neutral or park if automatic, and rev the engine. If the battery is failing, the headlights will get brighter as you press the accelerator. A completely flat or dead battery is easy to identify, it simply won’t start at all.

How to fit a new battery

For safety reasons, we advise you use protective eyewear and gloves, as car battery acid is highly corrosive and can leak.

Step 1: Before removing the old battery, ensure you have all of your PIN codes and settings for your car’s electrical systems to hand, such as the satellite navigation system, music system and radio, as they may need to be reset.
Step 2: Make sure you are parked on a flat, level surface – engage the handbrake and remember to keep the keys nearby in case the central locking system activates when the old battery is removed.

Step 3: Identify the negative and positive connections (negative is usually coloured black and marked ‘-’ while the positive pole is usually red and signed ‘+’. Label if necessary.

Step 4: When removing a battery, always remove the negative terminal first as failure to do so could damage your car’s electrical system. Next, loosen the positive terminal, then the clamps or screws securing the battery in its housing TOP TIP: Keep the old battery upright at all times during removal to minimise the risk of acid spillage.

Step 5: Set the new battery in its position, making sure the negative and positive posts are in the same position as the battery removed. Check this before tightening the clamps or screws that hold the battery in place. Remove the plastic protective covers from the new battery posts and then securely reconnect the positive (+) terminal followed by the negative (-) terminal. Remember to dispose of your old battery at your local recycling centre or scrapyard.

Posted In

  • Electrical
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