Understanding the working of motorcycle batteries

Different types of batteries

Batteries have become a very important component of today's automobiles. Now, every vehicle have its own battery. In this post we will know about the automotive batteries and their working. The automobiles generally use lead acid batteries, as they are cheap and can store a significant amount of power. These batteries are available in two varieties

1) Flooded type

2) Maintenance free or sealed type.

Both of them are used on motorcycles, but the use of maintenance free batteries is increasing due to their advantages over the flooded type. Most of you would be aware that, engines also contain Alternating Current Generators (ACG), which produce AC current whenever engine runs. This current can be used to operate all the electrical equipments of the vehicle. Than what is the need of a battery? Friends, the most important task a battery perform is to operate the starter motor, which otherwise can not be run by the current produced by the Alternating Current Generator. Apart from starting, it can also be used to operate some more components like horn, side indicators etc. 

Connection, positioning and charging of the battery

The batteries in motorcycles  are generally placed inside the right side cover and are mounted using suitable fixtures, so that they can not move. The negative terminal of the battery is connected to the frame and its positive terminal is used to supply power to different components. The chassis of the motorcycles is considered as negative terminal for wiring other electrical components. All the equipments which run on battery are wired in such a way that their one terminal is connected to the positive line and other to the chassis. The chassis in this case is called ground as it act as a large negative source. Grounding of the chassis decreases the number of wires to almost half and hence the the problems related to wires are also reduced to half. It also reduces overall weight & production cost and  simplifies the the overall wiring. The chassis can even be positively grounded i.e. the positive terminal of the battery is connected to it and negative terminal is connected to the equipments. This will causesno problem in functioning of electrical equipments.   For charging the battery, the power generated by the ACG is used. The AC current of ACG is converted in to DC by a rectifier unit and is supplied to the battery for charging.

Construction and working of automobiles battery

Battery of a motorcycle

The motorcycles generally consist of 12 volt Lead acid batteries. They consist of 6 cells of 2 volts. These electrolytic cells use lead electrodes and dilute sulphuric acid as electrolyte.  This electrolyte consists of water and sulphuric acid in ratio 3:1 . Spongy lead in pure form is used as positive while lead peroxide is used as negative electrode. The electrodes are dipped in tho the electrolyte to form 2 volt cells. Six 2 volt cells are used to form a 12 volt battery. Each cell has many positive and negative plates. Different cells are separated from each other by using separator plates.


Discharging of battery

The sulphuric acid exists as H+ and  SO4 − − .  The two electrodes of the battery have different electrochemical potential. When they are  connected to a load the H+ ions move towards the positive electrode and react with it to form PbSO4 and H2O.  The SO4 − − ions on other hand move towards the negative electrode and react with it to form PbSO4  .This leads to the deposition of PbSO4 on both the electrodes.  During all these the H+ ions absorb electrons from the positive electrode while SO4 − − ions give electrons to the negative electrode. This creates excess of electrons at the negative while dificiency of electrons at the positive electrode. This excess and deficiency helps in current flow through the external circuit. As the battery discharges more and more H2O  is produced. This dilutes the electrolyte. Further, the formation of   PbSO4 at both the electrodes lead to their deposition on them. All these factors slow down the reaction and  finally the current flow stops completely at the end and we say that the battery have discharged.


Charging of battery

For charging the battery its positive terminal  is connected to the positive  DC source terminal and its negative terminal is connected to  the negative terminal of the DC source. Now the  H+ ions present in the solution are attracted towards the negative electrode and the SO4 − − ions are attracted towards the positive electrode. The H+  ions react with   PbSO4  on cathode and forms lead and sulphuric acid. by taking electrons. The     SO4 − − ions in electrolyte react with  anode and form   lead peroxide (PbO2) and sulphuric acid (H2SO4). During this reaction the the concentration of the electrolyte is restored and the electrodes are also restored to their original state. This helps in restoring the original level of potential of the battery  and it becomes ready to use once again.

So friend this was all about working of a lead acid battery. We will be further posting some more exiting information related to motorcycle batteries in our next post. Please subscribe our newsletter to receive our posts through email.