How Long to Leave a Car Running to Charge Battery? (Explained)

Like others, car batteries have a limited running capacity, and they will wear down in time. Thus, one thing you’ll likely experience with your car as it ages is when the battery dies, and you’ll need to charge it. That’s one common reason why you need to jumpstart your car. With this in mind, you may wonder:

How long to leave a car running to charge the battery? Once your car is up and running, a few minutes of letting it help the battery charge further. However, it would be better to drive your car for at least 30 minutes to make sure the battery receives continuous charging. If you don’t do so, you may have to do another jumpstart.

While batteries get drained with many use of accessories, they also get charged as the engine runs. In this article, we’ll cover everything you need to know about charging your battery. This way, you’ll know what to do in case you will need to jumpstart your car.

Without further ado, let’s get into it!

How Long to Leave a Car Running to Charge Battery

How Long Should I Leave My Car Running to Charge the Battery?

As I said earlier, a dead car battery simply means you won’t be able to start your car without a jumpstart.

Thus, you need to make sure that the battery gets charged enough so you won’t have to do another jumpstart once you do.

In general, if you were able to start your car, let it run for a few minutes. The few minutes will give your battery some time to charge. Moreover, you may unhook the clamps in the reverse order of how you put them on.

Another thing is to make sure you use your car for around 30 minutes or more. Such a time would be enough for you to avoid another dead battery and another jumpstart.

The longer you’ll use your car, the better the chances of not having a dead battery on your next engine start.

Does Starting a Car and Letting It Idle Charge the Battery?

The good thing about a car battery is that it’s charging while your engine runs.

While car batteries provide electricity to all the car accessories and even to the engine, it also gets some power as the car runs.

For this reason, it’s not that big of an issue of your battery died all of a sudden.

Still, despite this fact, it will all boil down to how much your battery can get and to how much it gives. If you can calculate such, you can know how long you’ll need to have the engine running.

For instance, the engine gets around 100 to 130 amps from the car battery whenever it starts. On the other hand, an engine that runs for 15 minutes only gives the battery around 3-4 amps.

With this in mind, you need to remember that while the battery also charges, a couple of minutes of engine running won’t compensate for the lost power.

For this reason, you’ll need to have your engine run longer if you want to avoid another dead battery and another jumpstart.

Many people believe that idling your car for around 15-20 minutes will suffice your battery to recharge for the next startup.

This concept might be genuine for older vehicles. However, it’s unlikely the same for newer models.

If you’re running your car with a dead battery, make sure that it runs longer than 30 minutes to be sure.

car battery charging

How Many Miles to Charge a Car Battery?

The answer to this question depends on a variety of factors. For instance, if your car has a new battery, a short five-mile drive would suffice for your car to charge.

However, if you can run it for 70 miles, it would be more than enough to avoid another jumpstart.

Take it as a rule of thumb to drive your car as long as you can if you jumpstarted it due to a dead battery.

This way, you can ensure your car battery gets enough power to start your engine again the next time.

Moreover, it would be best to have your wiring systems checked. If your car battery is new, it can be worrisome to think that it went out immediately.

One of the common reasons for this is that the battery doesn’t get the proper amps for every engine run.


A dead car battery happens from time to time to every driver. Thus, it’s not surprising that you would experience such a thing once in a while.

A lot of things can be the reason for a dead battery. However, the good thing is that it can get resolved through a jumpstart, especially for manual vehicles. Also, the car battery can charge when the engine is running.

In the end, it will all boil down to you understanding how much time your car battery needs to charge. As soon as you understand such, you can also know what to do the next time it happens to you.



Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more