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BATTERY IGNITION SYSTEM OR COIL SYSTEM

 It is employed in Petrol Engines And used in Automobiles.

 Construction :

 It consists of a battery , ignition coil, condenser, contact breaker, distributor and spark plugs. 

Working :

The Ignition Switch is switched on and the engine is cranked. The cranking of the engine opens and closes the contact breaker points through a cam. 



When the contact breaker points are closed:

1. The current flows from the battery to the contact breaker points through the switch and primary winding and then returns to battery through the earth.

2. This current builds up a magnetic field in the primary winding of the ignition coil.

3. When the primary current is at the highest peak, the contact breaker points will be opened by the cam.

When the contact breaker points are opened :

1. The magnetic field set up in the primary winding is suddenly collapsed.

2. A high voltage (15000 volts) is generated in the secondary winding of the ignition coil. 

3. The high voltage is directed to the rotor of the distributor.

4. The rotor directs this high voltage to the individual spark plugs in the sequence of the firing order of the engine.

5. This high voltage tries to cross the spark plug gap ( 0.45 to 0.6 mm) and the spark is produced. This spark ignites the fuel - air mixture. 

Advantages :

* It provides better spark at low speeds of  the engine during starting and idling due to availability of maximum current throughout the engine speed range. 

* The Initial cost is low as compared with magneto Ignition System.

* The maintenance cost is negligible except battery.

* Spark efficiency remains unaffected by various positions of the timing control mechanism.

Disadvantages :

* Frequent battery down occurs when the engine is not in use continuously. This causes starting trouble. 

* The weight is greater than magneto ignition system.

* Wiring Mechanism is more complicated. 



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