Have you just experienced that galling moment of turning the key in a car and being met with nothing but a deafening click? Our car battery buyer’s guide will show you how to pick the correct replacement battery for your car, saving you both time and money.
The purpose of a car battery
The main purpose of a battery is to provide the power to start the car and to power its features, such as the door locks and media system, when the ignition is off or in the accessory position.
Once a car is running, its alternator – an engine-driven generator – will effectively provide the electrical power required for its systems and charge the battery.
This means, when you stop the engine, the required power for a restart will be available, provided everything is working properly.
In petrol and diesel cars, you’ll generally find a large 12-volt battery that provides the required power for starting.
Some cars, particularly luxury ones, may have an additional 12-volt auxiliary battery that is designed to support the main battery and provide power to comfort and convenience systems.
Hybrid and electric cars also have 12-volt batteries, like normal petrol and diesel cars, as well as larger traction batteries that are used to provide the power to drive the car.
The 12-volt battery in such applications often provides power for a wide array of features, including lighting, braking and steering, climate control and motor power control systems.
The different types, ratings and sizes of batteries
If you browse new car batteries for sale, you’ll see a plethora of options – and the sheer volume of choice can be overwhelming.
Lead-acid batteries, absorbent glass mat batteries, silver calcium batteries, enhanced flooded batteries, lithium-ion batteries, and more, all feature differing chemistries and construction.
And then you have to consider the specifications of each battery, including cranking amps, cold cranking amps and reserve capacity, which detail how the battery performs and what it can do.
You’ll also need to consider the dimensions and terminal position of the battery, to help you secure the correct replacement.
While that all might sound baffling, if you’ve never shopped for a battery before, worry not – because identifying and ordering the correct new battery isn’t difficult.
Picking the right battery for your car
If you have access to the owner’s handbook for your car, look for a section titled ‘Battery’ or ‘Battery replacement’. Here, you’ll often find the required specification of battery for your car, which will allow you to easily identify and buy the right car battery.
If you can’t find such a section, have a look for one called ‘Technical details’ or ‘Specifications’. Usually, these lists of information will include the type and specification of battery needed.
A quick phone call to a dealer or battery retailer should also allow you to confirm the type of battery you need, and many battery shops and manufacturers have useful online lookup tools.
Alternatively, you can look at the battery in your car itself. It should be clearly labelled, allowing you to check its specification and order the correct replacement.
Many batteries will have a two- or three-digit designation, known as a group size, that is a standard provided by the Battery Council International.
A battery marked 94R, for example, will be 315mm long, 175mm wide and 190mm tall. The ‘R’ element of its code means that the positive terminal is on the ‘reversed’ side, the right side.
If you can see such a code on your battery, you can compare it online and see what specifications you need to match, which will further help you obtain a suitable new battery.
However, it’s still advisable to check with the manufacturer or another source, just in case your car has an incorrect battery fitted.
Why it’s important to pick carefully
There are some problems you can run into if you pick a battery that doesn’t meet your car’s specifications.
The first is that it might not physically fit, as the tray or compartment for the battery is designed to hold and secure a certain size of battery.
Get too small a battery and it might float around and be at risk of damage; get too large a battery and it simply won’t fit in the space.
It’s also possible to get a battery with terminals that aren’t in the right place. The battery could fit, and be correct in terms of its specifications, but the cables might not reach the terminals.
If a battery’s electrical specifications don’t match that required by the car, you can otherwise encounter all manner of problems.
A battery with a Cold Cranking Amp [LK1] [LK2] (CCA) rating that is too low could, for example, struggle or fail to start your car in cold weather.
Or, if you pick a lead-acid battery instead of an Absorbent Glass Mat (AGM) battery for a car with a stop-start system, the system may be unusable or quickly damage the lead-acid battery.
This is why, if you want to avoid problems and extra costs, you need to check the listed specifications for your vehicle and buy a battery that matches those requirements.
How to fit and care for your car’s battery
If you need to install a new battery in your car, Parkers has a guide that explains how to do that here. If you buy a battery from a retailer, though, they may include fitting for free.
You can also prolong the service life of any car battery by bearing in mind these basic battery-care tips. This is ideal for keeping down the cost of ownership of a car.
And if you’re interested in buying your own battery tester, check out our guide on the best battery testers for all budgets here.
Don’t forget that old car batteries need to be carefully disposed of. Your local recycling facility probably has the provisions to do so, if you need to get rid of an old battery.
