Car Battery Sizes Guide

The car battery is the ‘heart’ of your car. It is what helps the engine to start by supplying power to the spark plugs to ignite the fuel. It powers the lights, the indicators, your windscreen wipers, and so many other ‘quality of life’ features in the car. Without a battery installed, your car simply will not work. Car batteries should be replaced every few years to keep the car running well, and it’s important to pick the correct size – not just because the battery trays in different models of cars are different sizes, but because there are different power outputs too, and the wrong power output could damage sensitive components in your car.

Are car batteries different sizes?

Car batteries come in different sizes, and to complicate matters even further, it’s not just the size of the battery that you really need to pay attention to. Other things to be concerned with include:

  • The location of the terminals
  • In particular, the location of the positive terminal
  • The type of the terminal (standard post, Japanese post, side terminal, or square bolt-through)
  • The number of cells
  • The voltage
  • The cold cranking amperage
  • The Amp/hour rating

At best, if you purchase a battery that is the wrong size, it may not sit properly in the vehicle. This could be dangerous if the battery became dislodged while you were driving. It’s also possible that an incorrectly fitted battery could damage your car, or simply fail to get it started at all. If the battery does work, then it may not last as long as the correct battery would be expected to last.

What do car battery group sizes mean?

The Battery Council International has assigned numbers and letters that represent the 'group size’ that a battery belongs to. The group size is based on the make, model and engine type of the car that the battery is designed to fit. A lot of cars will accept batteries from more than one group, so it’s important to make sure that the battery that you are thinking of using will actually work in your vehicle. Not only should the battery output the right amount of power, it should fit snugly in the tray, so that it is not prone to becoming dislodged when the car is in use.

There are dozens of battery group sizes, to cover 12 volt batteries for passenger vehicles and light commercial vehicles, 6 volt passenger car and light commercial batteries, as well as batteries for electric vehicles, and for heavy-duty commercial use.

What group size is my car battery?

You can find the battery group size for your vehicle in its owner’s manual. The group size will usually be a number (For example, most Honda, Nissan and Toyota vehicles accept Size 35 batteries), or a combination of letters and numbers, such as 22NF or 26R.

If you do not have the owner’s manual for your car, then the next-best place to find the information is on the battery that you are replacing. Most original batteries have the group size printed on the label on the top or the side of the battery. The label should also tell you the reserve charge and the cold-cranking amps for the battery. It’s useful to keep these figures in mind if you are buying an off-brand replacement.

If you’re not confident that the battery fitted in the car is the right type, then don’t just guess. Talk to an expert and get them to tell you what your car needs. Most parts stores will have directories of the different types of battery needed for different makes and models of cars. You can also use an online battery selector to find your battery group based on the make, model, year and engine size of your car.

What is the battery size for my car?

When you come to replace the car battery, it pays to shop around. Prices can vary massively between suppliers and you can expect to pay more if you simply call someone out with a vague battery query, compared to going to a shop and purchasing the exact battery you need and fitting it yourself.

Using an online battery selector will help you find the correct size of battery. The amp-hour and cold cranking amp ratings are minimums, and if you find a battery that offers more than that, then you can expect that battery to perform better, but you can also expect to have to pay more for it.

If you are buying a battery from a store and have the opportunity to inspect it on the shelves, try to get one that is no more than six months old. The date of manufacture is printed on the battery. Some makers use the standard date format that we are all familiar with, but others use a lettering system instead, with A being January, B being February and so-on, working up to M for December (I is not used). So, D16 would be April 2016. This makes it a little harder to tell at-a-glance how old the battery is. Try to stay away from older batteries because a car battery will slowly lose charge when it is sitting in storage, even if it is brand new and has never been connected to a car.

Car batteries can be expensive, so it makes sense to seek advice if you’re not sure what type of battery you need. In the long term, this will ensure that you get a battery that lasts longer, and that performs better in your car.

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