Will a car battery recharge itself? Let’s find out

Just like any other battery, a car’s battery stores chemical energy and converts it to electrical energy. Your car’s engine requires this energy to start and implement certain functions such as the ECM, sensors, lighting, electrical dashboard components, AC, music, and so much more.

Don’t worry, I’ll explain how a car battery works later. For now, just keep in mind that your battery will drain as it supplies electrical energy to the car.

This means that it needs to recharge even as it supplies the right energy to the engine. Without that, its charge levels will drop to a point where it can’t power the car.

Matter of fact, your battery needs to maintain a minimum charge percentage of 74% to be able to fulfill its role in the engine. If this percentage drops, it won’t be able to work until you recharge it, bringing the charge level back up to at least the minimum recommended percentage above.

Will a car battery recharge itself?

Fortunately, a car battery is designed to self-recharge. Again, don’t worry, I’ll tell you how in a bit.

How Does a Car Battery Work?

Just like any other battery, a car’s battery stores chemical energy and converts it to electrical energy, which your car requires.

The battery generates electrical energy in a fairly elaborate manner. When you connect it to the engine, it immediately activates and becomes active.

This action triggers chemical reactions within it, a process that results in the flow of electrons from one electrode(material) to another within it through an external circuit. This flow generates electrical energy.

The engine relies on two types of energy, depending on the task involved. For motion, it depends on the mechanical energy that comes from the internal combustion system. It’s only for the starting process and the electrical components sector where it requires electrical energy.

The battery is mostly involved when the engine is starting. After the engine has started, the alternator takes over, providing the electrical power for things such as the ECM and sensors, lighting, AC, and music system. It’s only when the demand for this electrical energy surpasses what the alternator can provide that the battery will step in to offer the additional power.

How Does a Car Battery Recharge Itself?

The battery self-recharges, using the alternator. You see, this electrical component of the engine directly hooks up to the engine power through a drive belt.

That means that crankshaft rotation will trigger alternator rotation when you start the engine. This will create mechanical energy, which the alternator will convert to DC(direct current), using a component called a “Rectifier.”

This current will then flow directly to the battery, effectively recharging it as the engine runs.

How Long Does It Take for a Car Battery to Recharge Itself?

The answer depends on the car and how discharged your battery is. In many cars, though, the battery will take around 30 minutes to recharge itself when the car is running, assuming the battery is not badly discharged.

Will the Battery Recharge If You Let the Car Sit?

The short answer is NO. When the engine is shut off, all its components go into idle mode. That means the alternator stops sending direct current to the battery even as the battery drains the same current it had stored.

If this goes on for a long, the battery will drain severely and need to be recharged externally before it can start working properly again. That’s why you’ll find that many cars that have sat idle for too long will have trouble starting.

How Long Can The Battery Hold Up When the Car Is Idle?

On average, the battery will die after the car has idled for 4-8 weeks. How long it will hold up depends on its condition.

Can You Revive a Dead Car Battery?

The short answer is YES. To start with, a dead car battery refers to one whose voltage or charge levels have dropped beyond the functional level i.e 74%.

Fortunately, you can bring the battery back to life by charging it with your home’s electricity. It will take about 4-10 hours of recharging to do so, depending on how severely discharged it is.


The battery is what enables your car engine to start. It’s also what powers your lighting, and electrical dashboard components, among other electrical components.

For the battery to be able to function, it needs to have a certain level of charge. If its charge level drops beyond that level, the battery will die and only be able to come back to life if you recharge it externally.

Will a car battery recharge itself? Fortunately yes, but only when the car is moving or when the engine is idling.

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