Electric circuit in the car

Under supervision Of Prof. DR/ Saad Abd El Hamid

1- Ibrahim Atef Mohamed 2- Ahmed Atef El sayed 3- Mohamed Ahmed Abd El Mawgood 4- Hany Ahmed Ibrahim

Battery is the most important part in electric circuit in the car. It is the part which supplies electricity to indicator and generator.

If more ampere-hours are required, two (or more) new and identical 12-volt batteries can be connected in parallel. If you connect two 12-volt batteries in parallel, and they are identical in type, age and capacity, you can potentially double you original capacity. If you connect two that are not the same type, you will either overcharge the smaller of the two, or you will undercharge the larger of the two.

The recommended parallel and series connections are as follows: [Source: Interstate Batteries] Connected this way the batteries will discharge and recharge equally. When connecting in series or parallel and to prevent recharging problems, do NOT mix old and new batteries or ones with different types. Connected this way the batteries will discharge and recharge equally. When connecting in series or parallel and to prevent recharging problems, do NOT mix old and new batteries or ones with different types.

There are six types of battery terminals-SAE Post, GM Side, "L", Stud, combination SAE and Stud, and combination S.A.E Post and GM Side. For automotive applications, the SAE Post is the most popular, followed by GM Side, then the combination "dual" SAE Post and GM Side. "L" terminal is used on some European cars, motorcycles, lawn and garden equipment, snowmobiles, and other light duty vehicles. Stud terminals are used on heavy duty and deep cycle batteries. The positive SAE Post terminal in slightly larger (by 1/16") than the negative one. Terminal locations and polarity will vary. There are six types of battery terminals-SAE Post, GM Side, "L", Stud, combination SAE and Stud, and combination S.A.E Post and GM Side. For automotive applications, the SAE Post is the most popular, followed by GM Side, then the combination "dual" SAE Post and GM Side. "L" terminal is used on some European cars, motorcycles, lawn and garden equipment, snowmobiles, and other light duty vehicles. Stud terminals are used on heavy duty and deep cycle batteries. The positive SAE Post terminal in slightly larger (by 1/16") than the negative one. Terminal locations and polarity will vary.

Alternator The alternator is an important part of the engine because it perpetuates the reproduction of power. The battery supplies the initial boost the engine needs to start the vehicle. The alternator takes over and replaces the power used in the battery by the starting of the engine.

alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.

Common Problems and Solutions When jump-started a severely discharged battery can cause the alternator to overload and internally fail. If this occurs replace or charge the battery before replacing the alternator. This will help prevent a second alternator failure. Most vehicles use a multi-ribbed belt connected to the engine to rotate the armature inside the alternator. If the belt fails it should be replaced immediately. Belt tension should be taught. If it isn't, check the belt tensioner, it may need to be replaced or the incorrect size belt may have been installed. Either of these conditions can cause the vehicle to stall and not restart.

Distributor Cap and Rotor The distributor cap and rotor are two essential pieces that distribute electrical current to the spark plugs. The distributor cap connects to the spark plugs directly using a spark plug wire. The number of plug wires connected depends on the amount of spark plugs that are in the engine. For example, an eight cylinder engine will have eight plug wires.

The rotor is designed to spin inside of the distributor cap, just missing the terminals inside the cap. A worn or damaged rotor can cause your vehicle to run rough, or even stall completely. The rotor is rotating at the same speed as the camshaft which also happens to be 1/2 the speed of the crankshaft.

Spark Plug Wires The function of spark plugs wires is to link the coil, distributor and spark plugs together. The coil turns twelve volts of incoming electricity into 20,000 to 50,000 volts and sends this jolt through the coil wire, which is connected on the other end to the distributor. Inside the distributor is a rotor that spins, and directs this current to the proper spark plug wire at the correct time, creating the "spark" at the plug. Without these wires, no car would even turn on.

Identification The spark plug wires normally run from the top of the engine to the cylinders on the sides, although some configurations differ. There will be one plug per cylinder in normal applications, so a V6 will have six, and a V8 will don eight plug wires, not counting the coil wire. Each end will have a boot on it to attach the wire either to a spark plug, the distributor or the coil. Generally, each end will be different sizes and therefore impossible to mix up.

Spark plugs Various Spark Plug Conditions These spark plug images depict various conditions inside a particular cylinder or all cylinders and will help troubles Normal Condition An engine's condition can be judged by the appearance of the spark plugs firing end. If the firing end of a spark plug is brown or light gray, the condition can be judged to be good and the spark plug is functioning optimally. hoot the problem. Normal Condition An engine's condition can be judged by the appearance of the spark plugs firing end. If the firing end of a spark plug is brown or light gray, the condition can be judged to be good and the spark plug is functioning optimally. hoot the problem.

Dry and Wet Fouling Although there are many different cases, if the insulation resistance between the center electrode and the shell is over 10 ohms, the engine can be started normally. If the insulation resistance drops to 0 ohms, the firing end is fouled by either wet or dry carbon.

Overheating When a spark plug overheats, deposits that have accumulated on the insulator tip melt and give the insulator tip a glazed or glossy appearance.

Thanks