How Long Does It Take to Charge a Car Battery While Driving?

How Does the Car Battery Charge Itself?

The car battery uses the power of the engine to charge itself. The more you use the engine, the more juice the battery gets. Most new models of vehicles use an alternator to charge the battery.

When the engine is running, it generates electricity which in turn triggers a chemical reaction that charges the battery. The alternator is an electromagnet which comes on when it is activated by a serpentine belt. This serpentine belt is in turn connected to the engine of the car. When the engine is ignited, the serpentine belt turns and gives life to the alternator.

This may sound like a complicated setup, but it is important to understand how your car works since that will help you take care of it better. This is a helpful guide to learn how your car battery works.

How Long Does It Take?

But more than understanding the technical aspects of how the battery charges, you may find the knowledge of how long it takes to charge more practically useful. Suppose you are stranded somewhere or your battery seems to be low according to your odometer, revving the engine is one of the first things you would do to charge the battery.

The alternator (if it is in good working condition) will turn on even if your engine is on but is only idling. You can keep the engine on and still be sitting stationary in the parking lot and the engine will be providing electricity to the battery to charge it.

How long the battery takes to charge while driving will technically depend on how much charge the battery had to begin with. The answer to this question will vary depending on how old the battery is, how long the engine has been off for and whether the alternator is functioning well.

Often, when you find that your battery is giving trouble it may be because your alternator is not providing the battery with the required voltage to charge (12.6 V) it. With a fully functioning alternator and a healthy battery, it should not take long for the battery to charge while you are driving.

If you are driving on an open road and your engine RPM is sufficiently up, it should not take more than 30 minutes for the battery to charge. If you are driving within the city and have to make frequent halts at stop signs or in traffic, the engine RPM will naturally be low. In that case, it may take over an hour for the battery to charge.

Either way, it should not be a problem as long as your alternator is working healthy. If your alternator is fine and your battery has not expired, your car should not give you trouble.

Driving your car is the best way to charge your battery. Any other method is what you may need to use in the case of an emergency or when your battery is dead and you need to jump start the car. Trickle chargers are also one of the methods of charging your battery, but to be frank, nothing is as efficient and quick for charging your battery as driving your car and keeping your engine active.

How Frequently Should You Start Your Car to Keep the Battery Alive?

As I have explained above, the primary way your car battery charges is by drawing power from the engine when it is running. This means that the battery is likely to die out if your car is sitting in the parking lot without being used.

It is a common misconception that your car is not using the battery when it is not in use. However, the battery is slowly being drained even when the car is switched off. The car requires the battery charge if you have installed alarms, if the car has a GPS or if it needs to remember the position of your seat, directions you may have installed and other smart things cars can do in the modern age.

This means that when the car is unused, the battery is still being used without any recharge. For most mid-range cars that do not have too many gadgets and in-built features, you should be able to leave your car unused for a month without the battery dying out. However, higher-end cars that have several smart gadgets may drain the battery even in two weeks.

Of course, the main factor that decides how long your battery will lose charge is the age of the battery. How old is the battery and when does it expire? Often, the climate of a place can also impact how quickly a battery loses juice.

While you may not always have use for your car, especially if you live in a city where you do not need to use the car for the everyday commute, it is important to start the car to charge your battery.

The information provided above about how long it takes for a car battery to charge is helpful precisely in situations like this! The higher the RPM of your engine, the sooner your battery will charge.

So even if you take the car out for a spin for a few minutes on the weekends or simply turn the engine on and leave it on idle in the parking lot, it can keep the battery alive. If you use your car very infrequently, it would be advisable to run the engine for at least 20 minutes to be on the safe side.

However, the best solution to keep your battery charged is to get it out on the open road and drive it around for half an hour or so.


There are two things you should remember about your car battery. One, that if you have jump started your car in case of a dead battery, you need to give the battery a chance to charge itself before you can take it out.

If you take it out on a low battery, the engine will not be able to provide enough electricity for it to keep running. You may end up getting stranded anyway. If you are around your house, it may be a good idea to stay in the neighborhood and not drive too far in case the battery loses charge on the way. At least if you are close to home you can walk back and get help, or leave your car at the place it has broken so you can deal with it in the morning, in case you get stranded at night.

The other thing is that there is such a thing as overcharging your car battery. If the battery overcharges, it will heat up, therefore causing long-term damage. The electrolyte makeup of the battery, which causes the electrochemical reaction which charges it, can also corrode from overcharging.

While most batteries have an auto-shutoff device that prevents it from overcharging once it has regained power, it is important to pay attention in case the battery in your car does not have this provision. This applies in case you are using a trickle or a smart charger, though in some cases it may also mean it is inadvisable to drive your car for hours on end without giving it a break.

Wrapping Up

When people learn how to drive, they do not think about their car battery… until it dies on them. This can be a stressful experience for an inexperienced driver who has taken the car out on their own. One does not know what to do in such a situation. Even if you get some help jump starting the car, what do you do if the battery gives way again? For all these eventualities, I find that it is good to learn about your car battery and how to care for it, at an early age!

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