Back before ignition coils were in common usage, cars started in what we today would see as a strange and alien way – they were started when the driver, standing outside, turned on the engine by turning a hand crank. Have you ever wondered why turning a car on is so often called “cranking the car?” Well, that is the reason. “Cranking the car” is one of the English language’s many antiquated terms that has happened to stick around long after actually manually cranking our cars fell by the wayside as a victim to newer and smarter technology.
Ignition coils, those handy devices that in part mean we no longer have to stand outside our cars and turn a hand crank when we are ready to drive to the corner store or shopping mall, are also called spark coils, because they help the power from the battery amplify into the thousands of volts of power that are needed to spark the spark plugs. The need for the ignition coil is simple. Car batteries only have 12 volts of power. (In fact, older car batteries may only have 6 volts.) But, a car’s spark plugs, the small devices that fit into the cylinder head of some internal combustion engines and cause the spark that lights the gasoline and causes internal combustion, need many thousands of volts of power in order to start (not crank, keep in mind) the car. The ignition coil’s job is to convert low voltage from the battery (remember, 12 or even as low as 6 volts) into those thousands of volts needed to start the car.
Even though ignition coils represent admittedly newer technology than those old hand cranks, they have been used in different ways in the past. Until recently, a car had only one ignition coil. That coil worked through a distributor, which, true to its name, distributed the volts amplified by the ignition coil to all the spark plugs. Newer car models though, eliminated the middle man so to speak, in that they eliminated the distributer. Instead, newer, distributor-less car models use many, much smaller ignition coils. These ignition coils server either one or two spark plugs and are electronically controlled. In modern cars, the ignition coils may be either remote mounted or placed on top of and in direct contact with the spark plug.
One important thing to know about modern ignition coils is that they put into motion the “wasted spark” system. When one ignition coil serves two spark plugs that single coil generates two sparks for each cycle it is powered. The only fuel that is ignited is the fuel in the cylinder that is nearing the end of its compression stroke. The other spark, then, is “wasted,” hence the name “wasted spark” system.