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A flat battery is a frustrating and inconvenient automotive issue. If you find that your battery is often flat when you go to start your car in the morning, it could be because you need a new battery. But where do you start and how do you determine the correct battery for your vehicle? Read on to get some helpful tips.

Getting a New Car Battery

One option is to call into your local garage. They will select and install a battery that is most appropriate for your car and budget. There are several factors that have to be taken into account when choosing a battery and they include the electrical system of your car and the car battery group size that your vehicle needs.

The other option is to source and fix in a new battery yourself. It is not difficult to do and could save you a lot of money. You just need to know how to pick the right battery.

Auto mechanic replacing car battery

Different Types of Car Battery

There are two basic types of battery which are called wet cell and VRLA batteries. It is important that you choose the right type for your car as well as the correct group size.

  • Wet cell car batteries

These are also sometimes called flooded batteries and are a category of lead acid battery. Inside this type of battery, there is a liquid electrolyte so they can be recharged. This is done when the engine is running. If you have this battery in your car, you will need to check on the level of the diluted acid. The water in the solution can evaporate and will need to be topped up. Distilled water must be used and you must get the correct ratio of water to acid for the battery to work correctly. A version of a wet-cell battery is a semi-solid electrolyte battery which you may see described as a sealed battery. These do not have to be topped up.

There are two versions of the wet cell battery. The first is an SLI (starting, lighting, ignition) battery which will start your car with a short burst of energy and also powers the lights and ignition. However, once the car has started, the power that it needs to keep running is provided by the alternator. Most cars have this type of battery.

The second version is a deep cycle battery which can also be called a marine battery. These will last longer and are able to deliver energy over a longer period. They can be discharged repeatedly without getting ruined.

  • VRLA Batteries

This stands for valve-regulated lead-acid battery. They are sealed and do not vent gas (hydrogen) so they are perfect for small spaces that have ventilation and are easy to store. They are also very safe.

You have the option of a gel cell battery or an AGM battery. As the name suggests, the gel cell battery contains a gel electrolyte rather than a liquid one. They are very tough, highly resistant to heat and do not get damaged by shock. They work just like a regular wet cell battery but are sealed so there is no evaporation. You could also choose an absorbed glass mat battery where the electrolyte is held in glass mats. They work just like wet cell batteries but the battery acid cannot spill.

Battery car

Different Sizes of Car Battery

As well as the type of battery, you also need to choose the right size. Car battery sizes are described in terms of a battery group size. So, what does battery group size mean? It is an industry-standard that describes the height, width and length of the battery. It also describes the location of the positive and negative battery posts which is called the polarity. Because batteries are standard sizes, it makes it easier for vehicle manufacturers to design the engine compartments.

The battery group size is a simple industry standard so it will be easier for you to find the right battery when you need to replace it. You don’t have to get your measuring tape out to find out your battery group size, it will be printed on the label of the battery and will be stated in the owner’s manual. You can also use a car battery group size chart which is readily available online. The battery group is specific to the year, make and model of your car. The most common battery group sizes are 24, 24F, 25, 34, 35, 51, 51R, 52, 58, 58R, 59, and 65.

Manufacturers tend to favor a particular battery group size. Many General Motors vehicles in the US have side-post batteries. These do not have battery posts at the top, instead there are cable ends that screw into the side. The group sizes are usually 70, 74, 75 and 78. In contrast, European vehicle manufacturers such as Audi and Mercedes have batteries where the top posts are recessed. This results in the top of the battery posts being the same height as the battery. Also, there is often a specialized ventilation system on the battery. They are generally more difficult to fit than other batteries. You will find that most vehicles manufactured in the US and most Japanese imports use battery groups that have top-post battery fitments. These are the most common types and are the easiest to replace.

What if You Use the Wrong Car Battery Group?

It is very important that you use the correct battery group for your car. It can be confusing because some group sizes have the same width and length but you will soon find that they have different heights. If you purchase the wrong size, the battery will not fit properly into the battery tray or into the battery hold-down of your car. It is also possible that the battery post could make contact with the hood of your car which is metal. This could cause a spark or a short in the electrical system. If you are unlucky, it could even cause a vehicle fire. Batteries that are not secure can move around and come into contact with other engine components.

Related Post: Best Battery Trays, Best Car Battery Testers and Best Car Battery

Sources:

  1. How to Buy a Battery for Your Car – Your Mechanic
  2. How to Check a Car Battery – Wiki How

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