A Rundown Of Automotive Electrical Systems


Inside any given car, you’ll find a myriad of components which run on electricity. Each one of them is able to run thanks to a closed-circuit system of power, which comprises a power source in the form of a battery, and a means of keeping that power source replenished in the form of a generator. Let’s take a brief tour of the inside of your car, starting with the more essential items, and moving our way to the luxuries.

Starter motor

A car’s starter motor is required to get the engine turning, in order to ensure that oxygen and fuel can get into the cylinder. The starter motor operates at a high current, and so in order to turn it on, a low-current relay circuit is used, which uses an electromagnetic switch to draw a set of contacts into alignment and get the motor started. Once the motor has started the engine turning, the pinion will either be magnetically drawn from the flywheel, or it’ll naturally spin away from it thanks to some clever engineering.


In order to ensure that your battery is properly charged, it’ll need a steady supply of current. This comes from the generator, which translates the motion of your engine into electricity which will charge your car’s battery. Nowadays, this generator comes in the form of an alternator, which consists of a ring of coiled wire which sits on either side of a shaft with a magnet inside. As the magnet spins, it produces a current inside the wire through electromagnetic induction. This current is alternating, and must be passed through a rectifier before it can directly charge the battery.

Image result for Automotive Electrical Systems

Headlights and Indicators

Of course, no car is roadworthy without a working set of headlights and indicators. These are self-explanatory things with which everyone is familiar. They allow a driver to see where they’re going at night, and indicate to other road users and pedestrians where they’re about to turn. Lights and indicators are not on the ignition circuit, and thus they can be activated when the engine isn’t turning. This is a useful feature, but it’s one that can potentially drain your battery flat if you forget to turn your lights off when the engine’s off. With no charge coming into your battery, it’s got no way of replenishing itself.

Windscreen wipers

In order to drive in the rain, or in any sort of precipitation for that matter, you’ll need windscreen wipers. These require the key to be in the ignition, as they consume a great deal more power than your headlights. The longer your windscreen wipers, generally speaking, the more power they’ll consume – but it’s almost always going to be a negligible amount of power, and so it’s rarely worth worrying about.


Leaving to one side the crank-operated windows of yesteryear, most modern windows use electricity to raise and lower. Windows tend to be connected in parallel to the circuit, which offers them a level of protection against being overblown – but there still stands a chance that the motor might fail at some point or other. If your windows stop working, then you can usually have the motor replaced easily and cheaply.


A radio is a piece of equipment that’s required to get make a car journey go as quickly as possible. Modern radios come equipped not only with an analogue receiver, but a digital one, too. Connect a Bluetooth device and you’ll be able to stream music over your in-car loudspeakers wirelessly; but don’t play with your phone to change your music as you’re driving.

Heated Seats

Heated seats are a godsend on those frosty winter days. But they’re also great for other times of year, too. Heating your back and legs directly is far more effective than heating the air within your car’s interior – it’ll come into effect instantly, and it’ll work out cheaper, too.

Heated windscreens

If your window is covered in frost, then you might need to get out and scrape it off. Or, with the help of heated windscreen, you can just wait around for the ice to melt off. Of course, most of us are too impatient to wait for this to happen, and will hurriedly whip out a credit card and get to work removing the ice.

Where do I buy replacements from?

Your garage will be able to order any replacements you need. Audi, BMW and Ford Alternators are each available from specialist online retailers, so if you find that you need a new alternator, it shouldn’t be hard to track one down.