All You Need to Know About Car Batteries

Everything you need to know about car batteries

Your car battery is every bit as important for your vehicle as the engine and fuel supply. On many occasions car batteries are likely to be the reason why your car won’t start on those freezing cold mornings. There is nothing more frustrating than going out to your car in the winter, scraping the frost off the windscreen and turning the key only to find that your car won’t start.

A lot of car batteries are prone to failure because of the cold conditions, especially if they have been powering your car for several years already. This is all because of the number of mechanical components that need to spark into life during the ignition process. Sometimes your battery just isn’t able to cope with the initial cold temperatures – a bit like a runner on a cold morning struggling to loosen up their muscles.

In many ways, car batteries are just like the typical power supplies that you would find in your household television remote or other electrical devices; only they’re not the kind of battery that you can replace with any you find off the shelf in your local supermarket.

Car batteries are designed to be much more hard-wearing and typically last between four and five years. Once they are up and running, car batteries are powered by alternators until the engine is switched off again – making them vastly different to your household batteries.

Your mobile phone is a prime example here – it runs down while switched on unless it is connected to a power supply, but a car battery is constantly charged by the alternator (or at least it should be).

Common problems with car batteries

Common problems with car batteries include corrosion

Over time, like all car parts, batteries will start to degrade. While the alternator is designed to keep charging your car battery while the engine is running, it will inevitably lose some of its ‘juice’ as time goes by.

The extreme cold and wet weather can make it extremely difficult for batteries to provide the important spark, but the alternator can be at fault just as frequently as the battery itself. If there is an issue with the battery many owners will assume that the time has come to invest in a new one to see if that solves the issue. However, it is often the fault of the alternator failing to charge the battery and this could mean you buy a brand new battery that just runs itself down like the previous one.

Checking the alternator is a relatively simple process, so it’s the kind of task that you could add to your maintenance routine – whether you check the condition of your car and the levels of your fluids weekly, fortnightly or monthly. To start with, open the bonnet and locate the alternator, which is connected to the battery.

An alternator charges the car battery

Take a multimeter and set it to around 20 DCV. Then connect the negative terminal on the battery, followed by the positive terminal, and this should give you a reading. Anything around the 12-volt mark would be desirable in this case. At this point you can then start the car and this will test the performance of the alternator. When the engine starts the voltage displayed on the multimeter should increase to around the 14-volt mark – anything above this could cause damage to the battery by giving it too much power, while anything below this would indicate that it isn’t being charged sufficiently. You should then switch on any additional electrical parts in the car – such as headlights, the radio and interior lights – as this will affect the voltage reading. Again, if this drops below the original 12-volt mark then it may mean that the battery isn’t being charged by the alternator.

If your engine doesn’t start the first time you turn the key – as you would expect it to – it’s important that you don’t just keep turning it with the hope that the car will start. Doing this simply puts the battery and other electrical parts under additional stress and actually serves to decrease the likelihood of your car starting.

Instead you should try in ten-second intervals. If this still doesn’t work, leave the car for around 30 seconds before trying again so as to not cause unnecessary stress and to allow the charge that has been generated to reach the essential parts. However, if the car still won’t start it may be time to call for assistance in the form of jump leads from a friend, neighbour or family member; or from a breakdown service.

Corrosion is another common problem with car batteries – just like typical household batteries – and this can be resolved by coating a layer of petroleum jelly on the battery terminals that will discourage corrosion from developing.

Choosing a new car battery

All car batteries have a specific code. This doesn’t mean that it is the only one suitable for your car, but best practice is to replace it like for like when the time comes.

Car batteries are rated according to Amp Hours (Ah) and Cold Cranking Amps (CCA) and these refer to how long the battery will last if it is not charged and the power they have to turn the engine over on those troublesome cold mornings respectively.

As we mentioned earlier, best practice is to simply replace your car battery with one with an identical code – even if it is made by a different manufacturer. Most car batteries are identified by a three-digit code, such as these 063 car batteries that we supply. You should then check on the CCA and Ah ratings to make sure that you are buying a battery that is powerful enough for your car.

If you are ever unsure on exactly which battery to choose, you can use our fast finder by entering your vehicle details or you can contact us and one of our experts will be happy to help.

Removing an old battery and fitting a new one

When it comes to changing your battery over it’s vital that you disconnect the negative terminal first. This is to prevent any damage to the electrical system and it’s very simple to do. The terminals are usually given a plus or minus symbol, or are red and black so it is obvious which is which.

Start by loosening any clamps that hold the battery in place, followed by the cable and any screws or ties used for the same purpose.  Having done this you can then start to remove the positive terminal, followed by the battery itself – but remember that a car battery can be very heavy so be sure to use the handle and get some assistance if required.

You can then place the new car battery in the correct place, ensuring that you have the positive and negative terminals on the right side. Then you can start to connect the clamps and cables, ensuring that the positive is the first to be fully connected.

Prolonging the life of a car battery

Having chosen your new car battery you’ll want to make sure that it lasts as long as possible. One really effective way of prolonging the lifespan of your battery is to make sure that any electrical appliances are switched off when not in use.

A lot of car owners will have car chargers and other devices plugged in and each one uses power. It is vital that they are unplugged when you switch the engine off otherwise they will continue to take power from the battery which won’t be being charged itself.

You should also make sure that luxuries such as heated windows and mirrors are turned off when they are not needed, along with headlights on bright days (if you are able to do so), as they too will use a small amount of battery power.

If you know that you are not going to use the vehicle for a long period, perhaps because you are going on holiday, it may be worth disconnecting the battery from the vehicle to not only reduce the risk of corrosion and issues occurring when you go to start the car for the first time; but also to prevent thieves from starting the car and driving it away.

You can always take the battery out of the car and connect it to a battery charger if you wish, topping it up so it’s ready for anything. We keep a range of battery chargers in stock that plug into your home electricity supply and are suitable for all makes, models and sizes of car battery.

For more buyer guides and information key car parts – such as batteries – please come back to the Euro Car Parts blog soon.