Working of battery ignition system

In this battery ignition system, the source of the ignition energy is the ignition coil. This coil stores the energy in its magnetic field and delivers it at the instant of ignition in the form of a pulse of high voltage current through the high tension ignition cables to the correct spark plug. 

Working of battery ignition system

As we explained above in the ignition coil it is consist of two coils of wire. One wire wound around the other and another is insulated from each other. The primary wining with few turns of heavy copper wire and secondary winding with many turns of fine copper wire. 

One end of the primary winding is connected through the ignition switch to the positive terminal post of the storage battery, and another end is grounded through the contact breaker. The capacitor is connected in parallel with the contact breaker. One end of secondary wining is also grounded through the contact breaker and another end is connected through the distributor and the high tension ignition cables to the centre electrode of the spark plug. 

The primary winding of the coil is connected to the positive terminal post of the stored energy when the ignition switch is closed. If the primary circuit is closed through the breaker contacts, a current flows and its called as primary current. It is flowing through the primary coil, which is wound on a soft iron core produces a magnetic field in the core. A cam driven by the engine shaft is arranged to open the breaker points whenever an ignition discharge is required. When the breaker points open, the current flowing through the points now flows into the condenser. As the condenser becomes charged, the primary current falls and the magnetic field collapses. The condenser then discharges into the battery, reversing the direction of both the primary current and the magnetic field. The secondary winding consists of a large number of turns of very fine wire wound with the primary winding. The high secondary voltage is led to the proper spark plug by means of a rotating switch called the distributor, which is located in the secondary or high tension circuit of the ignition system.  

If a condenser were not used in the primary circuit, the high primary voltage caused by the collapse of the magnetic field around the primary winding would cause an arc across the breaker points. Spark timing is controlled by the crank angle at which the breaker points open, while the distributor merely determines the firing sequence of the spark plug.