How Far Can I Drive With a Bad Alternator? [Explained]

Certainly, you’ll agree with me that all-electric vehicles are powered by electric motors, with the help of a battery. But did you know that the electric motor isn’t the one responsible for powering the radio, headlights, and other electrical systems in your vehicle? Yes, the alternator is responsible for all of that, including helping to recharge your car battery.

In case you don’t know, an alternator is an electrical generator that helps to convert mechanical energy to electrical energy. Generally located near the motor front, the alternator has four major components: the rotor assembly, stator assembly, rectifier assembly, and housing. Speaking of the rectifier assembly, it comprises the diodes, which help in converting the alternator’s AC output to DC.

Furthermore, the diodes are a very essential component of the alternator. If they fail to function well, it means you’ll have a bad alternator, which is not good for your vehicle. That said, here’s a burning question: how far can you drive a vehicle with a bad alternator?

With a bad alternator, you can drive your vehicle for about 30 minutes (about 50km), if your battery is fully charged. One of the functions of an alternator is to recharge the battery. As the alternator is bad, it means the battery won’t charge and will only rely on its power.

Although you’ll be able to drive your vehicle to a certain distance with a bad alternator, it’s worth noting that it may affect your car battery.  That said, it’s wise to change your alternator as soon as you detect that it’s not functioning well again. In the rest of this article, we’ll further be sharing with you everything that you need to know about a bad alternator, including what causes it, and signs that you’re encountering it.

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How long will a battery last with a bad alternator?

As earlier mentioned, your battery is the most important factor to consider when it comes to driving a vehicle with a bad alternator. Surely, you’ll agree with me that one of the main functions of a generator alternator is to help recharge the battery. It does that by producing a slightly higher voltage than that of the battery. That causes a current to run into the battery until it reaches a higher voltage.

However, without a properly functioning alternator, it means there won’t be a means to recharge the battery when it’s running down. It’ll only have to depend on its power to start the vehicle, and this will only last for a while – depending on a couple of factors. For instance, if you’re using an old model with good spark plugs, chances are that you’ll be able to drive it more than 30 minutes before the battery runs out of energy.

However, if you make use of the latest model car, which packs a lot of features, such as infotainment systems, display, and computer sensors, it’ll only last you for a short while. That’s because the technology features will also consume some amount of energy from the battery. Furthermore, in case you make use of an old model gasoline car, a fully charged battery should be able to last you for several kilometers during the day.

What are the signs of a bad alternator?

As earlier mentioned, driving your vehicle with a bad alternator is very dangerous, as it might ruin the battery and the electric systems. So, to prevent that from happening, you must get familiar with the signs of a bad alternator.

  1. Having a dead battery- Certainly, a dead battery can be caused by a lot of factors – one of them is having a bad alternator. A generator alternator, when in bad condition, will fail to recharge the battery while the engine is running, which causes the battery to drain quickly. One way to identify if the problem is alternator-related is by jump-starting the car.
  2. Electrical failure – Apart from the battery, the alternator also powers a couple of other electrical systems. A sign that it’s not working properly is when the electrical systems are acting up.
  3. Dim or flickering headlights– Another signal to know that your alternator is malfunctioning is when you are experiencing dim or flickering headlights. The flickering sign most likely means that the alternator is finding it pretty hard to perform well.

What can cause the alternator to fail?

A host of factors can cause the alternator to fail. According to automotive experts, a typical lifespan of a new alternator is seven years. Apart from that, a new alternator, if properly used, can last up to 240,000 kilometers. That said, if your vehicle’s alternator has performed that long, it may start developing issues.

As stated above, an alternator has four major components: rotor assembly, stator assembly, rectifier assembly, and housing. If any of them fails to work, you’ll certainly experience a bad alternator. For instance, the rectifier assembly has diodes, which help to turn AC output to DC. If anything goes wrong with the diodes, it means the alternator will fail to perform. Other causes of bad alternators include jump-starting your vehicle the wrong way, having a fluid leak in the starter, and installing electrical systems that overload the alternator.

Can you jump start a car with a bad alternator?

In case you don’t know, jump-starting a car is a technique used in starting a vehicle with a dead battery. Of course, this requires connecting the vehicle to the battery of another vehicle or any other external power source.

That said, to the burning question of whether or not you can jump-start a car with a bad alternator, the answer is yes. However, ensure that the battery you’re connecting to is in a good condition (fully-charged). That’s so because your battery needs to draw a sufficient amount of energy from the external battery.

That’s not all! You also need to switch off your car, as well as other systems in both vehicles, such as the air-conditioner, CD players, radio, heater, and phone charger. can consume power. You need to conserve the battery’s energy.

By fully charging your battery, you should be able to drive it with a bad alternator, for a few minutes, to a mechanic shop.


How Far Can I Drive With a Bad Alternator? The answer is, you can drive your vehicle for about 30 minutes, so it would be about 50km.


Know the warning signs of a dying alternator