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How Do Car Batteries Work? Function + Protection + Lifespan

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A car battery is responsible for starting your car, powering its components, and supplying the electrical system. But how do car batteries work in practice?

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A car battery is vital to the functionality and lifespan of your vehicle. Your car won't start without one, and a battery that has middling health can impact your vehicle's overall performance.

As such, it's important to understand how your car battery works. This will help you better maintain your existing battery and know when it's time to upgrade to a new one. Let's explore everything you need to know:

How Does A Car Battery Function?

In short, batteries are devices that translate chemical energy into electrical energy. They are made up of cells that store chemical energy, which is then transformed into electricity on demand. Most petrol and diesel car batteries feature six cells, each of which can produce around two volts of energy for a combined 12 volts.

The majority of these batteries use a lead-acid chemical reaction. To do so, each cell features two plates, one made from lead and the other from lead dioxide. These plates are submerged in sulphuric acid, which acts as a catalyst and triggers a chemical reaction between them.

This reaction produces electrons, which generate electricity. The electricity then flows from the battery to start your car engine. The reaction is reversible, which is why your battery recharges as your engine runs, and that's why you can jumpstart it when it's flat.

When you switch the ignition on in your vehicle, this transmits a signal to the battery, telling it to start the chemical reaction. The electricity produced by this reaction supplies power to the starter motor, which then turns the engine over. At the same time, the battery offers power to the spark plugs, which ignite the air/fuel mixture that is compressed in the engine combustion cylinders.

The power created by the battery is then replaced by the alternator, which is responsible for supplying most of the current to the electrical systems in your car, as well as for keeping the battery charged.

The growth of in-car tech means that car batteries now have to power far more systems than before. From sat navs to music players and air conditioning systems, there are many things that place added strain on batteries and charging systems. This can increase the risk of batteries failing.

If Car Batteries Self-Charge, Why Do They Go Flat?

Car batteries should last around five years, or potentially longer, but this depends on how well they are maintained. Based on the types of journey you make, your vehicle's battery may begin to show signs of age at around three years.

In practice, your battery empties a serious amount of its energy supply in one go when you use it to start the engine. It is then gradually recharged by the engine as you drive. If you make a lot of small journeys, the battery may not have the chance to fully recharge before being used again.

As such, it's likely to degrade faster. This could result in the need to replace it more frequently than if you regularly made long trips in your car. Here are other factors that can drain your battery.

How To Protect Your Car Battery

It's possible to safeguard your car battery and make it last longer.

  • Going on regular drives of 30 minutes or more will help ensure it recharges properly.
  • If your car is used infrequently, invest in an intelligent charger that can be left connected for long periods of time without causing damage to the battery.
  • Be sure to switch off all electricals in your vehicle when you start or park your car. This includes the music system, heaters, air con, and windscreen wipers.
  • Dip the clutch when you start the car to reduce the load on the starter motor and battery.
  • Conduct regular battery maintenance by ensuring the terminal connections are free of debris and are tightly secured.
  • Clean the terminals regularly and, to help prevent the build-up of corrosive material on the terminal connectors, coat them with petroleum jelly.

Signs That Your Battery Needs A Health Check

If you notice that the engine cranks more slowly than usual and it's taking longer to start your car, this can be a warning that your battery is about to die. In general, this happens only once or twice before the battery goes flat, so don't ignore it.

Likewise, if you hear a clicking sound when you turn the key in the engine, there isn't enough power to crank the engine. You will need to jump-start it to get moving.

Watch out for loss of power in electrical systems like your windows, seats, lights or heaters. However, the most obvious sign is an illuminated battery symbol on your dashboard. This is caused by:

  • A failing alternator
  • Damaged cabling
  • A loose starter terminal

If you notice any of these issues, book an appointment with Autofusion to get your car checked out. A technician can either fix the problem or provide a replacement battery for your vehicle. Addressing any concerns as soon as they arise can help limit the cost and improve your car's lifespan overall.