Can My Car Run With A Bad Alternator?

Power - by Joe Weber - updated on 7/5/2024

When you turn the key in your car's ignition, a series of components spring into action to bring your vehicle to life. One of the unsung heroes in this process is the alternator. But what happens if the alternator fails? Can your car still run? Let's dive into the role of the alternator and what happens when it fails.

What Does the Alternator Do?

The alternator is a crucial part of your car's electrical and charging systems. Its primary job is to keep the battery charged after the engine is started and power the electrical systems while the engine runs. It converts mechanical energy from the engine into electrical energy, ensuring that everything from your headlights to your radio has the power to function while you're driving down the road.

Can a Car Run Without an Alternator?

In a sense, yes, your car will run without an alternator, but not for long. Here's why:

Initial Power Supply: When the alternator fails, you may not notice a problem right away. The vehicle will rely on the power stored in the battery. This means that if your battery is fully charged, the car will start and run as usual for a short while.
Battery Drain: As you drive, the battery will drain quickly because it's now supplying all the power for the car's electrical systems. Without the alternator to recharge it, the battery's charge will steadily deplete until there isn't enough power left to keep the engine running.
Electrical System Shutdown: Once the battery's charge drops to a certain level, the car's electrical systems will begin to shut down. The engine management system, fuel injectors, and other critical components rely on electricity, so the car will eventually stall and leave you stranded.

How Long Can You Drive Without an Alternator?

How long you can drive without an alternator greatly depends on several factors, including the health of the battery, its state of charge and the electrical demands of your vehicle. On average, you could get anywhere from a few minutes to an hour of driving time. However, this is very inconsistent and it's better to just stop driving the car if you know the alternator is failing.

Signs of a Failing Alternator

Recognizing the signs of a failing alternator is key to addressing the issue before it leaves you stranded on the side of the highway. Some of these signs are very similar to the signs of a failing battery. This makes it even more important to properly maintain your battery and vehicle to ensure years of long, stress-free drives. Here are some common indicators:

Dimming Lights: If your headlights or dashboard lights start to dim as you are driving, it's a clear sign that there might be an issue with the vehicle's charging system.
Warning Light: Most cars have a dashboard warning light shaped like a battery. If this light comes on, it's time to get your alternator checked.
Electrical Issues: Malfunctions in electronic components, such as power windows, climate controls or the radio, can signal alternator problems if they are acting strangely.
Strange Noises: A failing alternator can sometimes produce a whining or grinding noise in the engine bay.

Preventative Measures

To avoid the inconvenience and potential danger of driving without an alternator, regular maintenance is key. Have your electrical system, including the alternator and battery, checked during routine service appointments.

If you suspect that something suspicious is happening in your engine bay, drive over to Batteries Plus and we will test your battery and charging system for you, free of charge. This can help catch any issues before they become major problems, ensuring your car stays in tip-top shape.

Will A Better Battery Help if My Alternator is Bad?

A stronger battery won't solve the problem but it will help you get a little further down the road to the service station in a pinch. AGM batteries, like our X2Power Premium AGM line, have more power than your conventional automotive battery to give you that extra boost when you need it.

Tips to Drive Further When Your Alternator Fails

Towing services can be expensive. If you are only a couple miles down the road from the nearest mechanic, you may be able to squeak out enough power to get you there without calling a tow truck.

Jump the car: Using a second car or a jump-starter, jump the dead battery and head straight for the mechanic.
Let the donor car run for a few minutes: If you are using a second car for a jump, let the donor car run for a few minutes to allow enough time to pass for the dead battery to charge a little more before you start the car.
Swap the battery for a fully charged one: If you have a spare car battery at the ready, I applaud you. This is not something that most people have but if you do, you can quickly install the new battery while you are stranded and continue to the mechanic.
Turn off ALL electronics: This includes climate controls, radio and other accessories that might draw power from the battery.

Stay Safe and Keep Your Car Charged with Help From Batteries Plus!

While a car can technically run for a short time without an alternator, it's not a viable long-term solution. The alternator is essential for keeping your battery charged and your vehicle's electrical systems functioning properly. If you suspect your alternator is failing, it's best to address the issue quickly to avoid being stranded on the road. Stay proactive with maintenance, and your car will thank you with reliable performance.

Keep an eye on those warning signs and maintain regular check-ups to ensure your vehicle remains in top shape.

Batteries Plus is here to help you with all of your automotive battery needs. From batteries to chargers and even lights and other accessories, we have everything you need to keep your car running smoothly. Stop by your nearest Batteries Plus today to see how we can help you!