What Happens If Battery Disconnects While Driving [Explained]

You may wonder whether your car will die when you disconnect the battery with a running engine. There’s also the concern about the safety of the car in that scenario. So, what happens if battery disconnects while driving?

More often than not, the car will be running just fine if you remove both battery terminals. But during other times, the car could die. Keep on reading to find out why these things happen in different situations.

what happens if battery disconnects while driving

I’ll also share insights from my personal experience that’ll help you understand this engine and battery relationship a whole lot better. So, let’s dive in! 

What Happens If Battery Disconnects While Driving Fully [Explained]

If you remove the car battery, the engine will keep on running in most cases. I can say that from my own past and all the car enthusiasts I’ve encountered in my life. There are many people who can support this statement.

disconnected car battery

According to Annette Maxon from Get Jerry Car Insurance, the car will run after you remove the battery. That’s because the alternator takes over the role of the battery when you start the engine.

The battery only powers the electrical components before your engine. But once you’ve started the engine, it’s all up to the alternator. That’s why the car should keep on running even after removing the battery from it.

However, real life tends to vary a lot from the theories. And that could also be the case if you remove your car battery. In theory, the car is supposed to run after you disconnect the battery from a running engine. But that may not happen in your case. The engine could die.

Can you guess when the car will die if you remove the battery? I bet you have a faulty alternator if your car dies after taking the battery off. It happens because the alternator may not have enough power to keep running all the electrical components in your car.

If you want to know more about why a car dies when you remove its battery, I’ve compiled a dedicated guide for you. Check out my post on fixing the car when it dies after removing the battery to learn how you can solve this issue with detailed instructions.

How Can You Tell If The Car Battery Has Disconnected

If you’ve disconnected the battery yourself, you don’t need to be looking for any symptoms. In that case, you already know that the battery is no longer connected to the car. But the real question is how to tell if the battery got disconnected while you were driving.

The first major sign of the battery being disconnected is that the battery light will come on. But keep in mind that it’s not a guarantee that the battery is disconnected. The battery light illuminates when there’s any issue with the battery or the electrical system.

illuminated battery light

It could mean that the battery is dead or not charging. Besides, this light can also come up when the alternator has disconnected from your car. So, you should definitely check out your car battery if you see this light come up.

Secondly, the car engine could die. You already know how that works. When you have a weak alternator, it won’t be able to keep up with the electrical demands. So, the engine will stop.

Those were the most obvious signs of the car battery being disconnected. If you notice the battery light, pull over your car to a safe stop and inspect the battery. If the car engine has stopped, then check both the battery and the alternator. Make sure they’re connected before you inspect other issues.

Should You Disconnect A Car Battery While Driving

Now you know that disconnecting a car battery when driving won’t stop the engine in most cases. So, you may think that disconnecting the battery with a running engine is a good way to test the alternator.

But I am telling you clearly that disconnecting the car when driving is a bad idea. It’s not a good way to test the alternator as there are many other easier methods to test the alternator.

Moreover, disconnecting your car battery abruptly can cause several issues. The main concern when you do it is that removing the battery can create a sudden voltage spike. So, several electrical components can be damaged if you remove the battery all of a sudden.

It’s one thing if the battery gets disconnected on its own. But you’d have to be crazy to think of disconnecting the battery yourself. The effects of suddenly removing the battery are far worse in cars that have onboard computers.

When you remove the battery out of nowhere, the memory in the ECU can get erased. Once that information is lost, the car will not work the same way even after the battery is reconnected. For all these reasons, please avoid removing your car battery when you’re driving.

Are There Any Benefits Of Removing The Car Battery

As a sane person, you should only think of removing your car battery if you won’t use your car for a long period. That period could be a few months or more. Even if you remove the car battery in that scenario, you should only remove it when the engine is completely turned off.

If you do it while you’re driving, you already know how much can go wrong because of it. The main benefit of removing the battery in that situation is that the battery will remain good.

If you leave the battery in the car and don’t use it for a long period, the battery could damaged. You’d have to replace the battery when that happens. So, removing it is a good way to avoid that. 


Can a loose negative battery cable drain the battery?

A loose battery cable won’t drain the battery. But it’d make the battery charge slowly. So, a loose cable indirectly drains the battery. Besides, the electrical system may not work properly if you have there are loose connections.

Can a bad battery cause a car to stall while driving?

Yes, a dead car battery is one of the main reasons why your car would stall. While a faulty battery can also prevent the car from starting, it can also make the engine stall.

How far can you drive with a dead battery?

You’d be able to drive as much as you wish with a dead battery. But the main issue is that you won’t be able to start your car. So, you’d require a jumpstart every time you turn off the engine.

How to change a car battery while the engine running?

You shouldn’t disconnect a single battery cable when the engine is running. Let alone replacing the entire battery. Please act as a normal human and turn off the engine before you replace your car battery.


What happens if battery disconnects while driving? Now, you know why the car can die in some situations and why you can keep on driving in some cases. No matter which type of car you have, you should never consider removing the car battery when driving.

Doing so will have a negative impact on the electric system of your car. If the battery connections have come off, just tighten them and don’t fiddle with too much. I also have a guide on the effects of a car battery getting wet. Check it out if you’re interested.