Now I had a look earlier to see if I could find a suitable 3d model so I could show you the electrical system. But unfortunately, we don't actually have one at the moment. So I do apologize for that. However, I can talk you through the entire process, and hopefully that will help you understand why we have an electrical circuit for an engine, and why engines are becoming more and more reliant on electronics. The main reason that we require a battery for an engine is to start the engine. The battery does other functions in a car for example, such as supplying power to the headlights and maybe fuel your electronic dashboard etc.

But in terms of combustion engines, it is there to start the engine that is its primary purpose. So how do we start the engine? Well, we start the engine using a starter motor. Now this is a starter motor or what actually happens is starting to motor has a gear wheel and we push it in to the flywheel and the gear will engages with the flywheel and cause it to rotate. That all happens in this section here, a spin around, we may be able to see the gears but if not, I'll load up a model and show you in a moment. Okay, so it's happening in this section here.

I'll load up a separate model so I can show you that in greater detail. Okay, so here we are, we're looking at the inside of a internal combustion engine is the four stroke engine, you can see all the components. The starter motor engages with the gear teeth on the flywheel. See from this angle, we've got some gear teeth, and a little starter motor. Imagine that it faces this direction. It has its own set of gear teeth, and they'll slot into these points here.

And as the starter motor rotates, For example, clockwise, it's going to cause the flywheel to rotate as well. And that's going to rotate the crank shaft, and that's going to force the pistons up and down. And we can actually see that going here. And the pistons will be forced up and down and at that point, you can inject fuel. And after a few revolutions, the engine will start and it will be able to maintain its own momentum. Let's just start the animation again.

You can see all of the pistons are operating, the valves are operating as you got camshaft running through the middle, the flywheel is rotating. What you have to imagine is starts a motor, it actually engages with the flywheel and gives it that initial push in order that the pistons can move up and down and then we can inject fuel and get combustion. As soon as the engine is operating underneath its own power. We remove the startup motor and will take it away from the gear teeth on the flywheel and that stops the starter motor burning out sometimes, and I've actually had this happen to me to start a motor stays engaged with the gear teeth. And what will actually happen is to start a motor burns out you'll have a copper burning smell, and that's because the starter motor has been dragged along by the engine flywheel that shouldn't occur because the starter motor should disengage with the flywheel, it's just sometimes it gets very dirty and it tends to stick.

Not only that, but use a valve. It's called a solenoid valve to push starter motor into the flywheel annual use the spring to retract it again. If the spring gets tired, then all of a sudden your starter motor will not disengage with the flywheel. There is actually quite a common failure mode for starter motors. But anyway, we start the engine using the starter motor and we operate the starter motor using the electrical power from the batteries. Usually the voltage we use is going to be 12 volts or 24 volts direct current, that is to say a 12 volt DC battery or a 24 volt DC battery.

So that is the primary function of the battery. When used with an internal combustion engine, you may notice that we've smaller engines, you don't have a battery. This is because where there is no battery, you'll often have a pull cord. For example, with a leaf blower, you'll sometimes grab the pull cord and you'll pull it as hard as you can. And that gives the engine the initial push the initial momentum it needs in order to inject fuel, and then it will continue to operate under its own momentum. Without this initial push, you cannot start the engine.

Let's imagine for a moment we're injecting fuel into the combustion space can actually see our injectors here. We'll inject the fuel and what will happen or the engine is sitting as it is right now it's just sitting completely still, if we spray fuel into this space, nothing's going to happen, you may have heard the phrase flooding the engine. If that actually occurs, you'll get a lot of black smoke coming out of the exhaust. That indicates to anyone looking at the engine that you've used too much fuel and not enough oxygen, that's when you get black smoke coming out of the exhaust. If you get white smoke coming out of the exhaust, you've used too much oxygen or too much air and not enough fuel. And if you get blue smoke coming out of the exhaust, you're burning lubrication oil.

So black, white blue, too much fuel too much air and burning lubrication oil. So those are handy tips if you ever looking at the exhaust gas of an internal combustion engine, but let's not digress too much. Let's have a think about some of the other systems where we could use electrical current in order to make the engine more efficient.