Automobile Battery : The Power Supply

With this post I am highlighting the very basic part of an automobile, the Battery. Battery is the power house of an automobile, be it a car or a truck or a motorcycle. Batteries act as a power source for the vehicle, they provide power from sparking of the engine to lighting up the headlights. By this post you'll get to know what is a battery, what it is made of, and how it works. Lets have a look..

What is an automobile battery ??

A typical lead-acid automobile battery

First of all let's have a look at the technical definition of an automobile battery and it states that "An automobile battery is a type of rechargeable battery that supplies electric energy to an automobile." The sole purpose of the battery is igniting the engine so that the vehicle can start off and in addition to that the battery provides power to different parts of the car like stereo, headlamps, inner illumination etc.

What it is made of ??

Inside of an lead-acid battery

The most common type of batteries are lead-acid batteries where the lead part is the electrodes and the acid part is the electrolyte. The batteries contains a series of plates dipped inside the electrolyte which is Sulpuric Acid, you must have heard this name before in chemistry classes. There are partitions inside the battery which are called cells and the batteries are mostly defined by the no. of cells present in it. Most common ones used in automobiles are 6 cells batteries.
          Every battery has two terminals one is positive and another one is negative. Here in this case the negative terminal is formed by pure Lead plate and the positive one is formed lead oxide and these two terminals are present dipped inside the acid part which is sulphuric acid. each cell contains the positive and negative terminals and these series of six cells is covered up with the hard casing inside which the whole reaction takes place.

How it works ??

For this part you must scratch your mind and think about the chemistry part that you learnt in school. Think about ions, charge, current etc. Here are the equations involved:

The overall chemical reaction is:

At the negative terminal the charge and discharge reactions are:

At the positive terminal the charge and discharge reactions are:

Discharging:

Discharging a battery causes the formation of lead sulfate crystals (PbSO₄) at both the negative and positive terminals, as well as the release of electrons (e^-) due to the change in valence charge of the lead. The formation of this lead sulfate uses sulfate from the sulfuric acid (H₂SO₄) electrolyte surrounding the battery. As a result the electrolyte becomes less concentrated. Full discharge would result in both electrodes being covered with lead sulfate and water rather than sulfuric acid surrounding the electrodes. At full discharge the two electrodes are the same material, and there is no chemical potential or voltage between the two electrodes. In practice, however, discharging stops at the cutoff voltage, long before this point. The battery should not therefore be discharged below this voltage.

A amaron battery placed inside a car.

Charging:

The charging reaction converts the lead sulfate  (PbSO₄) at the negative electrode to lead. At the positive terminal the reaction converts the lead to lead oxide (PbO₂) . As a by-product of this reaction, hydrogen is evolved. During the first part of the charging cycle, the conversion of lead sulfate to lead and lead oxide is the dominant reaction. However, as charging proceeds and most of the lead sulfate is converted to either lead or lead dioxide, the charging current electrolyzes the water from the electrolyte and both hydrogen and oxygen gas are evolved, a process known as the "gassing" of the battery. If current is being provided to the battery faster than lead sulfate can be converted, then gassing begins before all the lead sulfate is converted, that is, before the battery is fully charged.

This is it about the Automobile Battery...Hope you liked the post..will come up with other interesting posts. Stay tuned to KnowTheAuto.com...Happy Reading!!!