How Long to Leave a Car Running to Charge Battery: Solutions

How long to leave a car running to charge battery is something that any car owner should know to avoid ending up with a dead battery. By properly charging and maintaining your car battery, you can avoid needing to jump-start your car.

How Long to Leave a Car Running to Charge Battery

Although car batteries can last for three to four years, they can show signs of weakening if you leave your car lights on or if the expiry date is approaching. In this guide, we take a closer look at how to charge your battery by driving your car.

How Long Should A Car Run to Charge the Battery?

A car should run for 30 minutes to charge the battery if you are obeying the speed limits and driving around town. You can also take a long ride on the highway so that the alternator charges the battery. This is the same case after jump-starting your car.

If you want the car to charge faster, you should drive the car somewhere with a higher speed limit. Your car charges your battery when you increase the revolutions per minute, as this moves the belt faster, pushing the alternator to improve the charging speed of your battery.

Man Driving The Car in Road

Keep in mind that if your battery is weak and old, you might have to drive for an even longer time to charge it. You should consider driving your car regularly for commuting so that the battery is constantly charged, as abandoning your car can cause the battery to die out completely.

You can also leave your vehicle running for a shorter time if your battery is newer. If you leave your car headlights on for too long, it can suck up the battery power, so you would have to charge it by driving for a bit. If it doesn’t start at all, you have to jump-start the car.

How Long Will the Battery Last Without Driving Your Car?

The battery will last for about two months without driving your car. If you have a new battery in your car and you don’t drive it at all, the battery would last for about two months before dying. If it’s an older battery, it will take an even shorter time.

If the battery is new, the charge will remain for about two weeks without having to start the car. The lifespan of your car’s battery depends on its usage, age, and quality of it. Generally, a car battery can last for two to four wheels before losing its charge if you are not driving it. The battery can go completely dead, so you can get it to work again through a jump start.

Cars Parked Beside Each Other

You might think that starting your car for a minute to let it idle once a week prevents a dead car battery, but this is not the case. Instead, it would drain the battery when you start it and leave it idle for only a minute. So, you would kill your battery faster if you do this.

So, if you want to keep your battery in shape, but you don’t plan to drive your vehicle, you need to crank it up at least once a week and let the car idle for 30 minutes. Car idling for 30 minutes would do the trick, but you can do better when you drive it somewhere or speed on the interstate at 70 miles per hour.

How Can I Charge My Battery Faster While Driving My Car?

You can charge your battery faster while driving your car by conserving onboard electricity and turning off any optional features that use the battery. Also, you should keep the revolutions per minute of the engine constant when driving, at a constant of 65 to 70 mph.

The 30-minute estimate also assumes that you are traveling at a constant rate and you can hit the highway speed to charge your battery even more. Also, keep the rpm constant by avoiding hills, road turns, and shifting gears. This is why you should drive on a straight path and hold the same speed.

Happy Woman Driving Her Car

Also, ensure that you are driving in a place where there won’t be traffic because 5 minutes being slowed down in traffic would add 5 minutes to the time it’s taking to charge your battery. If you want to reduce the use of electricity, you should turn the radio off, drive without heating and air conditioning, and turn the headlights off if you don’t need them.

If you have any touchscreens in your car, you should turn the brightness down. Do that for your dashboard lights too, and unplug your phone and your charger. Reducing your amp usage in different places will direct power toward charging your battery while driving. The more often you drive your car, the more your car battery will remain charged.

How Many Volts Are In a Fully Charged Vehicle Battery?

There are 12.4-12.6 volts in a fully charged vehicle battery. In a modern vehicle, you get a 12-volt battery under the hood, with six cells in it. Each of the cells contains 2.1 volts of power if it is fully charged.

So if the car’s battery is fully charged and the engine is off, the car battery would be between 12.4 and 12.6 volts. If your battery voltage drops, it will greatly affect the overall performance of your car. For instance, if it reaches 11.6 volts, that means the battery is already weak, and it has to be recharged.

Charging Car_s Battery With Red Cable

You can check your battery power with a testing tool, which allows you to check how much voltage is in your car. If you connect a multimeter to the battery after it has been unused for an hour, you can get the resting voltage. This is more accurate to check if the batter is weak. But with the car engine running, the multimeter should show between 14 and 14.5 volts.

Will Your Car Battery Charge When Idling?

Your car battery will charge when idling, but it would be at a lower rate than if you drove for about 30 minutes. That is because of different electronics that use up power in cars, like the heater or radio. It’s always better to run the car rather than idle.

The alternator is responsible for powering the electrical systems and also charging the battery. So, if you’re just leaving your car to idle, it’s not generating a lot of revolutions per minute, giving it a longer time for your battery to recharge. It can take up to several hours, and it consumes a lot of fuel while idling during an engine charge.

What If Your Car Doesn’t Start to Charge the Battery?

If your car doesn’t start to charge the battery, you might need to jump-start the battery or use a battery charger. A charger is a convenient way to charge your car battery without needing jumper cables and another car with a strong battery.

A battery charger is a tool that keeps your car battery healthy and charged up. When choosing a charger, you need to check the chemistry of the battery. For instance, an AGM battery would be charged by an AGM-compatible charger. The same goes for a lead acid battery. You can ask your mechanic to check the type of battery you use if you are unsure.

Mechanic Try to Recharge The Battery

Also, the voltage of the battery should match that of the charger. A 24-volt battery can only be charged with a 24-volt charger; anything more or less can lead you to buy a new battery since the old one would be permanently damaged. There are also different types of chargers, so it’s best to look closely before you buy another one.

If you don’t have a trickle charger and your car isn’t starting, the best thing to do is jump-start your car. Make use of jumper cables and another car to charge the battery. Keep in mind that after jumping your battery, you should drive your car for 30 minutes to charge it.

How to Jump Start a Car

To jump-start a car, start by connecting jumper cables between two cars, the working car, and the dying car. Once you jump-start the car, you can drive for about 30 minutes to charge the battery. If the engine doesn’t start immediately, you might have to replace the battery.

If you want to jump-start your car battery, you need jumper cables, heavy-duty gloves, overalls, a flashlight, the car’s owner’s manual, and another car. Follow the five steps below:

  • Arrange the working car and the car with the dying battery so they are beside each other.
  • Check for the battery terminals under the hood, which are usually enclosed in plastic caps. The black cable is connected to the negative terminal, while the red cable is to the positive one.
  • Then, do the same thing for the car that you want to jump-start, connecting the red and black cables. When connecting it, ensure that the engine is not touching any part of the battery aside from the terminals.
  • Then, try to start the car. If the engine doesn’t fire immediately, keep the cables connected and let the working car idle for a bit. Try again after a short time.
  • Once the car has started, you should leave both cars connected before unplugging. Then, drive the car for about 30 minutes so that the battery recharges.

When Do You Need to Jump-Start Your Battery?

You need to jump-start your battery when it is weak so you cannot start your car. Other reasons include a malfunctioning alternator, a faulty spark plug, and issues with the starter. If you notice that you have to jump-start your car often, visit a mechanic.

Here are some reasons why you might need a jump-start:

  • A weak battery is the main reason why you might need to jump-start your car. Batteries can become weak during cold weather conditions or if you haven’t driven your car for a long time. You would need a jump-start to get the car moving.
  • A starter problem can also affect your battery. Along with the car not starting, you might also hear a clicking noise when you try to start the car. The starter problem can be because of corrosion in the engine, loose electrical connections, and oil leaks. A mechanic can help you diagnose the problem.
  • A faulty alternator is another problem that can cause you to jump-start your battery. Aside from charging the battery, an alternator would power components like the headlights, electric steering, and wipers. With a bad alternator, the car would stall or the battery dies, even when driving.
  • A malfunctioning spark plug can also occur, which would leak oil or fluids in the engine and other compartments.

If you jump-start your car often, you need to contact a mechanic to inspect the engine and other components.

What is the Best Solution for Charging a Car Battery by Leaving the Car Running?

Idling a car and battery charge: Leaving a car running to charge the battery is not the best solution. Constant idling can damage the engine and waste fuel. Instead, use a battery charger or take longer drives to recharge the battery fully. Regular maintenance and driving habits play a crucial role in preserving the car’s battery life.


With our guide on how long to leave a car running to charge battery, you can properly take care of your car if the battery is down.

Here’s a rundown of our article: 

  • You should leave a vehicle running for 30 minutes to charge the battery.
  • Your battery would last for as long as two months or at least two weeks without driving your car.
  • You can charge your car faster by turning off electrical components and maintaining a stable rpm.

It’s important to visit a mechanic if your car is unable to charge your battery when you drive.


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