What Happens if Your Car Battery Dies While Driving?

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Woman driving a GM SUV through a rural road in the mountains POV from inside holding the steering wheel

Running out of battery power during a drive is a scary thing. It involves losing power to most of the components in your car, and it will strand you on the side of the road. If you want to know what happens if your car battery dies while driving, you came to the right place.

If your alternator is still healthy, a dead battery won’t change anything during your drive. If your alternator dies alongside your battery, then you’ll lose power to almost everything: your engine, all of the lights, HVAC, radio, dashcam, and even power steering. Prioritize safely pulling over before anything else.

I’ll talk about this topic and let you know what to expect. I’ll even clear up a common misconception about batteries and alternators in this case. Towards the end, you’ll see some tips on how to recover after losing power to your vehicle mid-drive.

The Role of Your Car’s Battery

All of the electricity in your car is pulled from the battery. In other words, any components that require a current are reliant on your battery. It will be hooked up to your battery directly and will keep taking power for as long as the part is running.

A man starting the vehicle by placing the key into the ignition starting up the electronics

Even if your car isn’t running and your radio is on, the radio will keep taking power from the battery until the radio turns off or the battery dies.

One of the biggest tasks of your battery is to start your car when you turn the key. This takes a lot of electricity, and the battery has to do it on its own since the alternator isn’t firing yet.

Understanding the Alternator

Since you don’t plug in your gas-powered car at the end of the day, how does your battery charge? This is where the alternator comes in.

The alternator is a little motor. It gets powered by your car’s engine and it’s connected to the battery. As your engine rotates, the alternator creates electricity and funnels it into the battery, reverse charging it.

In some cases, a healthy alternator can continue to power a car even when the battery is completely dead. This is only the case when the alternator can make enough energy to accommodate all the electrical components that need a charge.

What the Battery Powers

Your battery powers a lot of components across your car. It starts with firing up the starter motor — a part that ultimately starts your car’s engine. Other things that get powered by your battery are all the lights in the vehicle, powered seats, the HVAC system, radio, power steering, fuel pump, dashcam, plugged-in phone, and more.

Electrical wiring harness inside a vehicle going to and from computer modules like the ECU

Without a battery, your car won’t start. If you run out of electricity mid-drive, then a lot of systems will fail.

What Happens if Your Car Battery Dies While Driving?

If your car battery dies but your alternator is healthy, then nothing will change while you’re driving. Remember, the alternator is charging your battery.

As long as your engine is running and the electrical demand is low enough, then the alternator can do all of the heavy work. That means that your battery can die but your car will keep going.

The key is to turn off your high-use components like your stereo speakers and HVAC system. This will minimize the amount of electrical power your alternator needs to generate on its own.

A person pressing the car stereo power button

If your car is struggling, you can throw it into Neutral and rev a little bit to get more juice to your battery. You might also run into troubles when you come to a complete stop. Your alternator works best when the car is moving, not just idling.

Since the battery is dead, you’ll need to get a jump before starting your car next time. You can use a portable car jumper if you want to avoid flagging down a stranger to help.

The bottom line is that a dead battery doesn’t do anything as long as your alternator is working. But what happens if the alternator dies?

What Happens if Your Alternator Dies While Driving?

The results of an alternator dying while you drive are a lot more dangerous. In fact, these are probably what people think of when they imagine a dead battery. I’ve personally had an alternator die while I was driving, and I can confirm that it’s not fun at all.

Engine Dies

First and foremost, your car’s engine will stop running immediately. You might notice it puttering out a little bit as the alternator starts to die. Once the alternator is done and the battery depletes, your engine will just cut off.

Two people man and woman trying to jump-start a vehicle on the street in downtown of a city

It feels a lot like stalling a manual car. You’ll lurch forward and the gas pedal won’t do anything. Instead, you’ll start rolling to a stop.

Lights Turn Off

In addition, all of your lights will turn off. This means any dome lights, dashboard lights, and even your headlights. When my alternator failed, it was the middle of the night, so it was a terrifying time trying to navigate the backroads in complete darkness.

Since your car doesn’t have any electricity, none of the lights will turn on.

Power Steering Disappears

Another electrically controlled system is the power steering. Fluid is pumped around, and the pump needs a certain amount of power in order to operate.

Once the alternator is down, then you’ll need to tug on your steering wheel the old-fashioned way. If you’ve never driven an old car, this can be really shocking and can fluster you. Remember to turn using the hand-over-hand method on your steering wheel.

Radio, HVAC, Dashcam, etc. will Stop Working

In fact, every electrical component will drop out once your alternator and battery go dead. Things like your radio, AC, dashcam, heated seats, cabin lights, and phone charger will all cut out at the same time.

Close up of a Land Rover Defender climate control powered off

Anything that requires electricity will simply not work — like the applications on a phone that ran out of battery.

What to Do if Your Car Battery Dies While Driving

After reading what happens if your car battery and alternator die while driving, you’re likely pretty scared. The good news is that the process is pretty straightforward after this happens. Since I’ve been through it, I’ll tell you what I did:

Pull Over Quickly

The first step is to get to the side of the road as quickly as possible. Your car won’t have a functioning gas pedal. The power steering will be out, you won’t be able to turn on your hazards, and you’ll have no headlights.

Red car hatchback pulled over on the side of the road with sunset visible

Focus on pulling your car over. Even if that means having tires in the grass, that’s less dangerous than trying to coast in a car with no electricity.

Once you get out of traffic, then you can start finding a solution.

Set up Roadside Flares

Since your car won’t have any lights, there’s no way for passing cars to see you if it’s nighttime. For that reason, I’d suggest getting roadside flares set up. If you put together an emergency bag, then you’ll already have them on hand.

Car Roadside Emergency Kit with Jumper Cables

Car Roadside Emergency Kit with Jumper Cables
Car Roadside Emergency Kit with Jumper Cables

If you don’t have an emergency car bag, follow my guide so you’re prepared for next time.

If you don’t have flares, then you’ll want to get out of your car and walk away from it. Your airbags won’t go off if your car doesn’t have electricity, so you won’t be protected if someone swipes your car.

Try Restarting Your Car

In some cases, you can just restart your car and drive away. I’ll admit that this is uncommon, but it’s worth a shot.

If your car successfully restarts, then turn off your radio, AC, and any electrical components. You’ll need to minimize how much electricity your car uses until you get home.

Get a Jump

If it doesn’t restart, then you might need a quick jump in order to get home. If you have a portable car jumper, plug it in and start trickle charging your battery.

Portable Car Battery Jumper – NOCO Boost X GBX45 1250A 12V

NOCO Boost X GBX45 1250A 12V UltraSafe Portable Lithium Jump Starter, Car Battery Booster Pack, USB-C Powerbank Charger, And Jumper Cables For Up To 6.5-Liter Gas And 4.0-Liter Diesel Engines
NOCO Boost X GBX45 1250A 12V

Since the alternator is dead, this charge isn’t going to last very long. The hope is that you’ll have enough to get home successfully and then go from there.

If you’re still a long way from home, then I wouldn’t even bother jumping your car. A dead alternator won’t recharge your battery, so you can only use however much energy is generated from the jump.

Tow Your Car and Repair it

At this point, you either had enough power to crawl back home or you’re still stuck on the side of the road. In either case, you’ll want to get a tow to a nearby mechanic. Changing out an alternator is a pretty difficult repair, so it’s best to let a mechanic do it.

New car generator alternator and belt installed on tensioned shaft

Let them know that you think your alternator is bad. They’ll replace it and might even swap out your battery, depending on how damaged it got during the discharge.

Conclusion

When an alternator and battery die mid-drive, you’ll find yourself in a scary situation. Your car will shut down and you’ll lose functionality in most of the systems. I hope that this guide helped you deal with the situation and get out of there safely.

For more car guides, you can check out my website. I also have a handy list of car products that can help you. Feel free to comment below and talk about your experience with a car that died mid-drive.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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