The Regulation and the charging circuit. Under the hood of every car, there is a power team that furnishes energy for the automotive electrical system. This charging team has three members connected together. Let's meet them one at a time and see what each one does and how they work together in the circuit. First of course is the battery. Old powerhouse himself. The battery is stored kind of power, power in a package. It gets its great strength from chemical action. Look inside the case will show you how this works. A simple battery element is made up of two unlike materials, a positive plate and a negative plate, kept apart by a porous separator. When this element is put into a container filled with a sulfuric acid solution called electrolyte, a simple battery cell is formed. When the plates are connected, electricity will flow. By connecting many positive plates together and many negative plates together with separators in between them, more powerful elements are formed. Regardless of the size or the number of plates, each cell of an automotive battery can produce two volts of electrical pressure. When the six cells are connected together, the battery produces six times as much voltage or twelve volts of electrical pressure. Next we connect the battery to a circuit. Electricity will now begin to flow through the circuit and we call this electrical flow current. Current flows in a copper wire much like water flows in an open pipe, but it will not flow unless there's a push or a voltage behind it. In other words, current is the electricity that feeds the system, while voltage is the pressure or force that moves the current. Although voltage can be measured anywhere in the system, the source of the battery voltage is always in the battery. If the battery continues to pour out energy, it becomes weak and exhausted. Here's where the second member of the team gets into the act. So let's meet the generator. Like the battery, this member of the team is also a power producer, but it works in a different way. The generator converts mechanical energy from the engine into electrical energy to recharge the battery and power the system. Since the generator depends upon mechanical energy, it works only when the engine is running. Let's take a look behind this action to see how a generator works. This is a simple horseshoe magnet, the kind that picks up metal filings or nails. It has a North Pole and a South Pole. And between these opposite poles are invisible magnetic lines of force called magnetic field. If a piece of copper wire cuts through this magnetic field, a voltage is produced in the wire. For our purposes, let's forget about the horseshoe magnet except for the ends. In the generator, these ends are called pole shoes, and between them is the magnetic field. In place of the straight wire in the magnetic field, let's substitute a loop of wire with a separated metal segment attached to each of the ends. These metal segments, called the commutator, added to the loop of wire, make up a simple armature. As armature rotates, it cuts the magnetic field and more voltage is produced. If we use several loops with segments, we have an improved armature. This armature, as it cuts through the magnetic field, produces even more voltage. The armature of the modern generator then, is made up of many loops of wire. As it rotates, it cuts through the magnetic field between the pole shoes, developing electrical energy. Writing on the commutator are the brushes. These pieces of carbon are stationary bridges, which pick up current from the commutator and pass it along to the system. Next are the field coils. These are many turns of wire wrapped around the pole shoes and connected across the generator brushes. As the armature begins to turn, current passes through the brushes and into the field coils. This current is called field current. As it flows through the windings of the field coils, the pole shoes become electromagnets. As the armature picks up speed, more and more field current flows through the windings. This strengthens the electromagnets. And when this happens, voltage builds up fast, since the generator, like the battery, uses this voltage or push to move current, it must be controlled. This is why it needs the regulator. This important member is the captain of the power team, the guy who calls the signals in the charging circuit. In the regulator case, we find three units. We cut out relay, the current regulator and the voltage regulator. In simple terms, these units are three electromagnetic switches. We'll watch them go to work one at a time. First, let's hook up the charging circuit. We will show current in the main circuit with red arrows, current in the field circuit with blue arrows, and voltage levels in the battery and generator with green flashes. As shown here, the battery powers the electrical system to start the car. It will continue to power the system until generator voltage is high enough to carry the load. The first signal is passed as soon as the generator voltage rises above battery voltage. In other words, the generator is saying that it is ready to charge the battery and power the system. When this happens, action is taken by the cut out relay. Enough electromagnetism has been built up in the coil by generator current to operate the switch and close the points. This completes the generator to battery circuit. As the cut out relay completes the circuit, current begins to flow into the battery. This is the charging action of the generator. Power is also available to the rest of the electrical system, as needed. The generator will now supply power to the electrical system as long as the generator voltage is higher than the battery voltage. When the generator slows or stops, generator voltage drops below battery voltage. Now, starts to flow from the battery back to the generator. The cut out relay immediately opens or breaks the circuit, preventing the battery from discharging into the generator. Now let's consider the second electromagnetic switch in the regulator. If the generator is allowed to produce voltage, without some kind of control, it would knock out the rest of the system with too high voltage. That is why the generator needs the voltage regulator. This device controls the generator's fuel current. Fuel current enters the voltage regulator points and travels through the regulator frame to ground. A closer look shows that the voltage regulator uses a voltage-sensitive coil and a limit setting spring to limit generator voltage. The tension on the spring allows the current to flow until coil magnetism is strong enough to open the points and break the field circuit. So let's assume that the generator builds voltage until it reaches the voltage regulator's top limit. Coil magnetism is now strong enough to overcome the tension in the limit setting spring. The points open, sending the current through a restricted bypass. Between coil magnetism and the pole of the spring, the points open and close rapidly. In this way, generator voltage is held to a safe limit, and the battery and accessories are protected from overheating or possible burnout. Now there may be times when the system will call for more and more current. More than the generator can safely put out. This is why it needs the current regulator. Like the voltage regulator, this electromagnetic switch also controls the generator's fuel current. Fuel current flows through the current regulator frame, passes through the points, and completes its circuit to the ground. Here, under normal conditions, the points are held close by a limit setting spring, and instead of a voltage-sensitive coil, the current regulator has a current-sensitive coil, which will break the field circuit when the danger point is reached. This time, let's assume that the demand on the generator is great, and that it has built up current output to its maximum safe limit. Coil magnetism is now strong enough to open the points. As in the voltage regulator, coil magnetism and spring tension will very rapidly open and close the points, sending field current through a restricted bypass, and this controls field current and generator output. In this way, the generator is kept from burning out. For here is the kind of player who just does not know when to quit. A three-point rule of thumb will help us remember the functions of the members of the charging circuit. First, when the generator is running too slow, the regulator calls on the battery alone to power the system. Next, when the battery is fully charged, and the electrical load is normal, the regulator calls on the generator alone to power the system. And finally, when the load is heavy, and the generator cannot handle it alone, the regulator calls on both the battery and the generator to power the system. So we see the electrical charging circuit, the battery, the regulator, and the generator is an efficient power team, and if given reasonable care, we'll give long and dependable service.