Vehicle battery is a component that store electrical energy for the vehicle use. Note that the battery is only a stored component. It mean the battery only use to save the electricity.
So, the battery (in general ) has 12 Volt voltage at full charge.
When we use the battery, there is discharge voltage that makes the battery voltage drop in slowly.
But because the battery has no ability to recharge, it make the battery going to empty if it use for long time.
But, we never change the battery daily right ? it mean the batteries voltage always stable in 12 Volt.
What makes the battery stable even it always use ?
The answer is simple, the vehicle has charging system. The battery has no ability to recharge so that we need another system to recharge the battery.
Battery Function in Vehicle
the main responsibility of a vehicle battery is to provide the starting current needed to start the car, it is also responsible for powering all the other electrical components of the car, such as the headlights and the radio.
But, the battery job only on the beginning.
Once the engine run, we don’t need the battery anymore. Why ? because the charging system will active following the engine. The charging system will provide electricity for vehicle electrical needs and to recharge the battery.
How Charging System Work ?
Charging system use an alternator to change the rotational motion into electrical energy. The alternator connected to engine pulley, so that when engine run the alternator rotor rotate.
The alternator rotation will make the electromagnetic interception that makes the electron movement. It result electricity.
But the electricity provide by alternator sill in Alternate current. While the vehicle and battery need direct current. So that, it is not connected directly to vehicle electrical system.
But there is a diode bridge to change the AC current to DC. After passed the diode bridge, the electricity can be used to power up the vehicle electrical system (head light, horn, radio).
The thing you need to advice that the amount of voltage from charging system is not stable. When the engine run in low RPM, the resulting voltage can be lower than 12 Volt. In this condition, charging system can not use as electricity provider.
It mean battery still need to power vehicle electrical.
But when engine run at high RPM, the charging voltage can be higher than 12 Volt. It is bigger than standar voltage. So that every vehicle has voltage regulator. It use to regulate the amount of voltage to the vehicle electrical system.
So in conclusion, can a car battery charge is self ?
No, the car battery has no ability to recharge. It is only an electrical stored component.
But the vehicle electrical system has charging system. It makes the battery in the car keep stable, so we don’t need to replace it everyday because the battery never in empty voltage.