A car battery or an automotive battery in general is built on lead-acid battery technology. This technology basically converts chemical energy into electrical energy and has been there for decades. It is reliable for the harsh environment of vehicles like extreme temperature swings and vibrations.
Lead-acid batteries for cars or SUVs are made of specialized hard plastic shell which contain Lead oxide plates and Sulphuric acid as electrolyte. This in fact is an arrangement of six cells of 2.1 volts each connected serially to give an output of 12.6 volts in fully charged condition. Most vehicles with exception of very heavy trucks use 12 Volt batteries. The size and capacity of battery (in ah) varies depending upon the size of the engine of your vehicle.
The Chemical Process
In a lead acid car battery, electrical current is created during the discharge cycle as the lead oxide plates absorb Sulphate from the diluted Sulphuric acid solution. When the battery is charged, the process is reversed. Current is pushed through the positive terminal into the plate pack, causing it to shed the sulphate it absorbed during discharge.
Chemicals and metals are added to the lead oxide of the plates in order to stabilize them and to slow down their rate of degradation under extreme usage.
Typically a car/SUV battery lasts anything between 3 to 4 years. Car batteries are different from the batteries used for inverters and other standby applications. To know the difference read – Difference between Inverter and Automotive Batteries.