How Long Should I Let My Car Idle To Charge Its Battery

How Long Should I Let My Car Idle To Charge Its Battery

Has your car battery ever gone dead? Well if you don’t use your car regularly, it is highly possible that you have faced this before. Many of us have been stuck with a dead battery, more so you can never be sure when the battery is full. How long should I let my car idle to charge its battery?

A car battery can charge while the car idling. The alternator will be able to charge the car. It takes 2 hours to charge a flat battery with average amps while the car is idling.

This all depends on how rarely we use the car and how long before the battery flats out. For some people, it may take less than 2 hours, for others more. The type of battery, the alternator, and devices that draw power impact how the battery charges.

Can I Charge My Battery While The Car Is Idling

Can I Charge My Battery While The Car Is Idling

Yes, your car battery will charge while it is idling and this is possible because of the alternator in the battery itself. The alternator will charge the car’s battery by providing it with electricity.

The alternator, on the other hand, is driven by the engine in your car. As long as the engine is on, the alternator will keep on charging the battery.

It is a give-and-take sort of relationship between the two. But it is safe to keep a few pointers in your mind.

To charge the battery, you need to make sure that the engine is running and idling. You also need to make sure that your alternator is in good condition.

Even if your alternator is in good condition, a completely dead battery won’t charge up.

That’s why you need to test both your battery and the alternator. This is done with a simple device called a multimeter. We have a complete guide on how to test a car battery and an alternator.

How Long Does It Take

How Long Does It Take

The time it takes for a car battery to charge when the engine is idling depends on how empty the battery is. A flat battery takes the longest to charge. Half-empty batteries will charge way faster.

It should take 2 hours, give or take, to charge a car battery with the engine idling. As long as there’s no drain on the battery and it’s healthy, it shouldn’t take more than 2 hours to charge the battery to 80%.

Problems with charging arise when you have a lot of drains hooked up to the battery.

The alternator will turn on at idle but does not produce the maximum current. So, if you are trying to pull out a high amount of power from the battery while the car is idling, the input charge will be a deficit.

This may cause important components like the car’s computer or the ignition to fail.

From this, we can conclude that the battery gets charged slowly at idle and it would be the wiser decision to not place a high electrical drain when it is idling.

How Long Should I Idle My Car To Charge My Battery

How Long Should I Idle My Car To Charge My Battery


While some people would recommend idling your car to charge the battery, it is not widely recommended.

In older vehicles, idling your car for 15-20 minutes can give your battery enough charge to restart your vehicle, but it is not always great for your vehicle.

In modern cars, there are battery management systems in place that will extend your battery life. These technologies also work to limit your car’s ability to charge at low RPMs.

So unless you are traveling at higher speeds, your battery will receive a small amount of charge from idling.

Idling for too long can cause problems for your car also. It will contaminate the car’s oil faster, which offers less protection for your engine.

It’s far better to drive to charge the car’s battery. The battery will charge up way faster.

Even after considering the fact that your battery is dead, it will not take a lot of time for it to charge.

The battery will demand a lot of current because of the fact that it has been discharged. Around 60 amps or more.

[Related Article: What Are The Reasons My Car Battery Won’t Charge]

Does Idling Drain Your Battery

Does Idling Drain Your Battery

Yes, idling your car for as little as two minutes will be the equivalent of driving a mile! Leaving your car idling will waste not only gas but does not allow your battery to charge.

Not allowing your battery to charge will drain its power during idling.

During idling, your engine and alternator run slowly. The alternator will provide electricity to charge the battery.

However, if you are using high-powered accessories, then the alternator won’t meet the electrical demand. In these instances, your battery will make up the difference and become drained.

Can A Car Battery Die When It’s Running

Can A Car Battery Die When It's Running

Yes, your car battery can die when it is running. Your car battery’s purpose is to provide the initial power required to start your car’s engine.

Once the vehicle is up and running, the alternator can take the ability to run your car’s electrical system and maintain battery levels.

If your battery is old or already damaged, there is an increased chance of it dying while the car is in use. There should be some signs of damage to the battery beforehand, though.

Common symptoms need to jump-start your vehicle regularly, dim interior and exterior lights, and the battery is periodically dying or shutting off the engine.’

Final Thoughts

It is quite possible that you are in that stage of your life where you don’t really need to drive around anymore. Well, you have deserved it, but what can you do about your car?

You can use a smart charger that gives your battery exactly the charge it wants. Unlike a traditional charger, it will not overcharge your battery and you can plug it in and forget the rest.

Otherwise, you can always take it around for a spin. Always prefer charging your car battery when you are driving instead of when the engine is idling.

[Related Article: 3 Best Battery Disconnect Switch(Buying Guide) 2022]

Related Questions And Other FAQs

How Long Does It Take To Charge A Car Battery

At idle a car battery can be functionally recharged in 75 minutes when at 50% capacity, or about 2.5 hours when fully discharged.

How Long Can A Car Battery Sit Unused Before Charging

Older vehicles with few electronics on board can go 3 to 4 weeks until the  battery is too weak to start the engine.

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