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Does a car battery charge whilst driving?

Does a car battery charge whilst driving? The short answer is yes, but it depends on the type of car!

Vehicle Types

There are two basic types of vehicles these days; those which have an internal combustion engine, and those which are all electric.

We’re seeing more electric vehicles on the road now than ever before. This technology seems to be improving with leaps and bounds at an ever increasing rate. In some countries, legislation has been passed to ban the sale of new petrol and diesel passenger vehicles in favour of electric alternatives. Manufacturers are ever refining this technology and competing to offer the best vehicles in this space.

The one thing that both of these vehicle types have in common is the need for electrical power, and a lot of it. Modern cars are complex machines which are crammed full of electronics and computers, all of which are power hungry and require a stable and powerful source of electricity to function.

The difference is how this power is used within the vehicle, and this influences how the battery is charged and managed.

Mobile Devices

In today’s world we’re all used to mobile electronic devices. From phones, to smart watches and everything else we use things that contain a battery which, as we use them, runs down and then needs to be charged up. Generally when we do this we connect the device to a charger which is plugged into the wall.

Electricity then flows from the outlet in your house, through a charger and into your device. When it’s fully charged, you can disconnect the charger and the process starts all over again.

When you think about it, a car is also a mobile electronic device. Just like your phone, it certainly doesn’t need to be plugged into a power source all the time with a long cable in order to work!

But unlike other mobile devices, cars contain a system to recharge the battery. This applies to both electric vehicles and those with an internal combustion engine. The difference is how effectively the battery is charged.

Think about it like this – for a non-electric vehicle, when was the last time you had to check your battery or recharge it before you took a trip? Have you ever seen an indicator like your phone showing the % charge of the battery?

How Electricity Is Made

Before we look into things further we should understand how electricity is made, as whether on a large scale to power cities or a small scale to recharge your car battery the process is the same.

There is a special relationship between electricity and magnetism. Without overcomplicating things, when we move a coil of wire in a magnetic field it will create electricity. In this way we can create electrical energy from movement.

In a power station, large generators contain huge coils of wire and magnets. These are arranged around a shaft so that when that shaft turns, the coils of wire are exposed to a moving magnetic field.

These generators are so large that they produce thousands of volts and create a huge amount of electrical energy which is then sent down transmission lines to thousands of homes – including yours. So when you plug in your phone charger, you are connecting to a huge power network which ultimately is powered by huge generators.

And on a smaller scale this is exactly how your car produces the power to recharge the battery.

Internal Combustion Engine Vehicles

In a traditional vehicle, the car is powered by an engine which burns fuel to provide the energy needed to move the car forward.

Some of this energy is used to drive other components like power steering, air conditioning and importantly a device called an alternator. It is the alternator which is the “power station” of your car – converting rotary movement into electrical power.

In this arrangement, the car battery serves two main purposes. First, it provides the initial electrical power to start the vehicle and run anything else before the engine is started. Second it stabilises the power generated by the alternator when the engine is running.

When the engine is running, the alternator supplies all the electrical power the car needs to function, plus enough left over to charge the battery. This may at first seem strange, but think about it for a moment. If it didn’t, then over time the battery would drain as it’s used to start the car and power everything up before the engine is started. If it wasn’t recharged, then it would fairly quickly get to the point at which you couldn’t start the car due to a flat battery.

Electric Vehicles

An electric vehicle is a different story because it doesn’t have an engine which burns fuel. Instead a large battery bank is used to power electric motors to drive the car forward.

Compare this to the internal combustion engine arrangement, and you will quickly realise that there is no other system in place within the vehicle which can recharge the battery completely. Everything is exclusively run from the battery system. This is why electric vehicles need to be recharged on a regular basis, and will have indicators on the dashboard to tell the driver how much battery capacity (charge) is remaining. Also compared to a regular car, the battery within an electric vehicle is huge and has a vast amount of energy.

With that said, whilst there is no mechanism directly similar to an internal combustion engine arrangement using an alternator, there is a system in place which can “recover” some electricity from the movement of the car.

This system is known as regenerative braking, and (without using a complicated explanation) works by using the electric motor(s) within the vehicle as a generator when using the brake. Whilst this does feed some power back into the vehicle’s battery bank, it is not enough to keep everything fully recharged. Eventually the vehicle will need to be plugged in to an external power source to fully recharge the battery.

Hybrid Vehicles

A hybrid vehicle is a combination of both technologies – a vehicle which has a large battery and electric motors plus an internal combustion engine. The arrangement of this means that the onboard computers can decide on which option is best based on the driving conditions, increasing fuel economy and reducing emissions.

In terms of recharging the battery, because the vehicle has an engine and alternator arrangement these vehicles will behave in the same way as a regular car in terms of keeping the battery charged.

The Wrap Up

As you can see, all vehicle types have a battery but use them in different ways. How they are charged, and how much depends on the configuration of the vehicle.

Like other components of your car, batteries have a lifespan. And at some point, we all will need a car battery replacement. If this is the case as a Perth mobile mechanic we can assist you in making the right choice and supplying the best replacement.

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