How a Car Battery works? How to choose a right Car Battery?


The Car Battery is a device that uses as a source of electricity for the entire electrical system of an automobile. The car battery is the main part of the electrical system in an automobile. Without the car battery, the engine cannot be started with the starting motor. 

The car battery supplies current for operation of the starting motor and ignition system when the engine is being cranked for starting. It also supplies current for light, radio, heater and several other accessory units when the generator is not operating fast enough to handle the electrical loads.

Car Battery
Car Battery

The Car batteries are of the following types.

1. Lead-acid battery
2. Alkaline battery:

  • Nickel-iron type
  • Nickel-cadmium type

3. Zinc-air battery.


The electrical system of a modern automobile consists of four main circuits and a number of branch circuits. The four main circuits are the generating circuit, starting circuit, ignition circuit and lighting circuit. All the main circuits are connected together and linked to the car battery.

Car Battery
Car Battery

The generating circuit is connected to one end of the car ammeter so that the meter registers in the charge direction when the current is being sent to the car battery. A wire connects the other end of the ammeter to the generator directly to the cable leading to the underground pole of the car battery. The starting or cranking motor is connected directly to the car battery through cables and a switch to provide a low-resistance path for the large current required ty the motor. ignition and ignition circuits are connected to the same side of the ammeter as is the generator.

Car Battery Uses

The branch circuits consist of special purpose lights, radio, gasoline, gauge, heater, cigar lighter, windshield, wiper and several other accessory units. All the branch circuits are also connected to the same side of the ammeter as is the generator so that when the generator is operating they receive current directly from it without going through the ammeter. When the generator is not running, these circuits draw current directly from the car battery or the ammeter which reads the discharge direction, because the current through it is opposite in direction from the charging current. When the demands of circuits exceed the generator output, the extra current is supplied by the car battery directly or through the ammeter.

Car Battery
Car Battery

Watch the video below for how to choose the right car battery:

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