Car Battery Charging

Car Battery Charging: Idling, Driving, and Efficiency

If you have a second car that you rarely use or work from home and don’t use your car as often, you might be wondering how fast the charge in its battery depletes. More importantly, you might be wondering whether the battery charges when the car is idling.

Do car Batteries Charge While Idling?

Car Battery Charging

Fortunately, the answer here is yes. Your car’s battery will continue to charge when the car is idling. The alternator will provide electricity which will charge the battery. Therefore, as long as your engine and alternator are functional, the battery will charge. However, it gets a little bit more complicated.

How long does a battery take to discharge?

The main reason why many people are curious about charging the battery while the car is idling is that their cars are rarely used. We are all familiar with the disappointment of trying to start a car after leaving it in the garage for some time and finding out that the battery is dead.

With most modern cars, you can’t disconnect the battery and just leave the car. The battery is responsible for more than just the radio. There are countless computers in modern cars that require the battery, even when the car is not in use. As a result, if you leave your car for around two to three months without using it, the battery will die, and it will not start.

How does a car battery charge?

To understand why your battery can charge when the car is idling, you need to know how battery charging works in a car. Your battery is designed to provide enough power to fire up your engine starter. Once the engine starts, it will continue running until you’re out of gasoline or there’s another issue with the engine.

The alternator is connected to the engine’s crankshaft through a belt known as the serpentine belt. As the belt turns, it spins a rotor in the alternator, surrounded by magnets.

AC current is generated when the rotor passes the magnets; it is converted to DC current and distributed to the rest of the car. The current provides electricity to all the car’s electrical components and finally charges the battery.

Will your alternator charge your battery when the car is idling?

As we saw earlier in this article, the alternator will charge your battery when the car is idling as long as the engine does not have underlying problems.

While the serpentine belt should rotate faster with your foot on the gas, your car’s ECU regulates its voltage. This means it charges at the same rate when you are actively accelerating as when the engine is idling in a parking lot.

How long should you idle the car to charge the battery?

Many people who have cars they rarely use idle them occasionally to keep the battery alive. However, you might be wondering how long you should do this to ensure that the battery is charged sufficiently.

Well, if you’d like to charge your battery completely, you should be willing to leave your battery idling for several hours. This is because there are many electrical components, especially in modern cars, all fighting for the little current from the alternator. The remainder is what goes to the battery.

Of course, this will also depend on the health of your battery, how much voltage your alternator produces, and the number of electric components in your car.

Therefore, if you plan to leave your car in the garage for a long time, idling it is not the most efficient way of charging the battery. The best option is to get a trickle charger, which will keep a low amount of voltage applied to the battery and keep it from dying.

Does the alternator work when your car is off?

If your car’s engine is off, then it is not spinning. This means that it will not rotate the serpentine belt, which powers the alternator. Therefore, your battery will not be charging.

The only way to charge the battery when the engine is off is by using another battery or a trickle charger.

Will the alternator charge the battery when the car is in neutral?

Most people won’t leave their cars in neutral for long, but knowing the battery will charge helps. The alternator will charge the battery.

Therefore, as long as you can start your car and the engine is working properly, you’ll still be able to charge your battery in neutral.

Will the battery charge when the car is in drive?

Most people know that the car’s battery will charge when the car is in drive. Otherwise, your radio and infotainment system would die after a few hours of driving.

How long does it take to charge the battery when driving?

You have decided to take your car for a drive around the block after leaving it unattended for some time. Or maybe you’ve jumpstarted the dead battery, and you’re now wondering how long you should drive around to charge the battery.

Most experts agree that you need to drive for at least 30 minutes to get any meaningful charge on your battery. However, this does not mean that 30 minutes of driving will recharge your battery fully. For that, you’ll need to consider how much of your battery was depleted and the general condition of your battery.

If your automobile has been sitting for a while, driving for 30 minutes will partially charge it before it dies.

How do you know that the battery is charging?

Car Battery Charging

If you wanted to check whether your battery is charging while the car is parked, you could use a multimeter. You should do this only if you suspect that the battery is not charging.

Whether you drive the automobile or keep it in a garage, the battery may eventually die.

To sum it up

Your car battery will still be charging when your car is idling. However, it is not the most efficient way of charging the battery, especially if you want to leave the car unused for some time.


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