Car Battery Technology

 

The molecular make up of a lead acid car battery differs in the charged state to the discharged state. In the charged state each cell is made up of electrodes of lead metal (Pb) and lead (IV) dioxide (PbO2) in an electrolyte of around 33.5% w/w or 6 Molar sulfuric acid (H2SO4). The discharge state is different with both electrodes turning into lead (II) sulfate (PbSO4) and the electrolyte losing its dissolved sulfuric acid, becoming primarily water.

 

Overcharging a lead acid car battery with too much voltage will generate oxygen and hydrogen gas by electrolysis of water. This gas is highly explosive and can be ignited easily.

 

Electrolyte in discharged car batteries is more likely to freeze due to the loss of sulfuric acid from the electrolyte mixture.

 

The humble lead acid battery holds the second lowest energy-to-weight ratio of any common battery, next only to the nickel-iron battery. The cells of the lead acid car battery have a relatively large power-to-weight ratio supplying very high surge currents. Being both lighter than comparable batteries and able to supply large amounts of cranking power, along with being low cost, lead acid batteries are the natural choice for use in automobiles.