How Long Can a Car Battery Last without The Engine On

Imagine going on a long-awaited vacation and coming back home to a dead battery just because the car engine was off the whole time! Well, this isn’t uncommon.

And this is why pros recommend you to start the engine once or twice every week! Today, we will tell you how long can a car battery last without the engine on; in short, how long can you not drive the car and yet keep the battery alive!

The Use of the Battery in a Car

Before you dive into how long a car battery will last without driving and the engine, you must know why a battery is added to the car. Well, your car runs with fuel. Then what is the job of a battery?

If it is not powering the engine or the car, what’s it doing?

The work of the battery is the keep the engine system of the vehicle sustainable. It changes the chemical energy and transforms it into electrical energy while keeping the engine system in the right condition. However, along with this basic job, it also does the job of lighting and some petty works.

Use of the Battery in a Car

It keeps the radio and clock active. Also, the alarm system is kept alive with the battery. So, you already know that to keep the engine system active, the car battery must last. But we don’t drive always! If you don’t drive or keep the engine on, how long it will take for the battery to die?

Longevity of a Car Battery without the Engine On

The period your car battery will last without the engine on depends on different factors. The age of the battery is a matter here. Also, the method of storing the battery will play a vital role in keeping the battery active. How you use the battery is a matter to think about here too. Yes, you can keep the battery unused. But you cannot do it for long!

New and Fully Charged Battery

If you are using a new car battery, it will last two weeks or more. However, in this case, you must ensure that you have charged it fully. You don’t need to recharge it from a generator for these two weeks. However, after two to three months, the battery will get discharged.

And if you are planning to keep the battery like this, no matter it’s new or old, the battery won’t last after two and half months. And with this battery, you won’t be able to start the engine.

Disconnected Battery

So, we have already learned how long the car battery will last without the engine on when it is connected. But what is the matter with a disconnected battery?

Will it last the same period? When it comes to a lead-acid battery, it will die when you pull power from the battery continuously.

It will occur after it has been discharged. So, the longevity depends on how you store the battery. The better your storing method is, the longer the battery will last. For storing, the temperature plays an important role.

After you have disconnected the battery from the car, if you are storing it at a low temperature, it will start discharging fast. However, if you are planning to store it at room temperature, it will last longer than the previous method.

And if you have kept a discharged battery at is low temperature for a long period, you won’t be able to use the battery after this. It won’t work!

Devices inside the Car

However, the lasting period of the battery depends on the features and additional devices of your vehicle. When these devices are moving inside the car, they will keep using the power of the battery no matter the engine is off.

The more devices you have added to the car, the more battery usage will occur. The radio systems will take power from the battery. Also, the battery will be used for the alarm systems and headlamps here. Even when the car is not in use, such devices require energy.

And this is why the battery runs out of power. And this is the reason why modern vehicles drain the battery faster than the older ones. The newer vehicles have more devices added inside. This type of battery-draining is called a parasitic drain. No matter you use these gadgets or not, they will keep draining the battery until it is zero!

Also Read; How To Install Car Seat Covers with Hooks


Wrap Up

We have told you all about how long the car battery will last if you do not use the car or leave the engine switched off. If you are staying home, you might plan to start the engine once or twice a week so that the battery gets the necessary charge. If you are on a vacation, we recommend you provide your key to a trusted friend to do your job!

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