Can A Bad Alternator Ruin A New Battery? A Failing Alternator

Batteries and generators play an important role in a car’s engine system. It keeps your car running smoothly every day. Therefore, when both of these parts fail, your car will certainly be affected. So, can a bad alternator ruin a new battery? The following article will help you answer this question.

Can A Bad Alternator Ruin A New Battery?

Dead battery or alternator is an incident that you would never want it to happen. Because this part belongs to the core detail of the engine system. It provides extra physical energy when the vehicle is running. When one of these two parts fails, it can affect the car’s power supply.

At this time, many people think that they are confused in choosing a repair method. Most of them will think about replacing this part. It is a good solution but has a very high cost, sometimes replacing it will not be the best choice for users.

To be sure, you should take your car to a car service center. These units will assist you in testing both the generator and the car battery. They will come up with the most effective troubleshooting solution for you.

So, how to handle battery vs alternator diagnosis? The following section of the article will give you details of the signs in each specific case.

Can A Bad Alternator Ruin A New Battery

How to detect battery is working or not?

Low battery

When your car does not start, most likely the cause is from the power source. However, to be sure, you should check carefully before drawing a final conclusion. Here are some signs to help you come to the most accurate conclusion:

  • Batteries will perform at their best for a period of 3 to 5 years. As the time goes on, the charge capacity will decrease. Therefore, based on the time of use, you should check this part. It is possible that your battery has appeared corroded.
  • Battery swelling occurs: When the temperature is too high, the liquid inside will expand. It will cause your battery to become bigger than usual. This phenomenon indicates that the power supply is low. The inflated battery may deflate if you hear a clicking sound when turning the car key.
  • When you turn on the ignition and turn on the headlights, you will notice that the lights are weak and dim. This sign indicates that the car battery system is weak.
  • Turn on the dashboard lights and headlights

Slow engine start

A slow engine start is the next sign that your battery has failed. Specifically, you will spend a lot of time starting up but may not bring any effect to the car. Or when you can start, your car will stop suddenly.

Corrosion of battery

When the battery terminals are corroded, it interferes with electrical energy causing the battery to not charge properly. Corrosion will continue to expand if you do nothing to prevent it. It is best to seek the help of professionals. They will help you remove the corrosion or replace the battery pack with a new one.

Strange smell

In fact, when the battery is oxidized, the lead-acid portion will leak and release sulfur gas. At this point, you will smell a very unpleasant smell of rotten sulfur. You won’t be able to do anything more than replace the battery pack with a new one.

Battery is warped

A bulging battery will cause this part to appear warped. The cause may come from the extremes of the weather. High temperatures will cause the liquid inside to expand. Similar to the strange smell, you will only be able to replace the battery in this case.

How to detect generator failure

How to detect generator failure?

So, can bad alternator drain battery? A failed alternator is the cause of your battery draining. In addition, it also causes a lot of other negative effects that you do not want. Here are the signs to help you recognize when your electrical machine has a problem:

Spindle and motor stall frequently

A broken generator will make it very difficult for you to charge the battery. At this time, the car battery will not have enough energy for you to start the car. At that time, your car will experience a stalling phenomenon right after you start the engine. For better troubleshooting, you should seek the help of professionals.

Headlights glow erratically

Dim or unevenly lit headlights are an indication that the generator is not working efficiently. Then, check the rewinder.

Dim interior lights

Same with headlights, if your interior lights are dim or glow unevenly, it could be from an inefficient generator that’s affecting the power supply.

Electrical accessories malfunction

Dead battery or alternator symptoms can be recognized by the indication of a malfunctioning electrical accessory. At this time, you may hear strange sounds coming from the stereo. 

In addition, you will also notice other phenomena: the clock runs wrong, the power window rotates slowly,… All of these phenomena come from a bad electrical machine.

Has a burning smell

The generator belt is subjected to constant tension and frictional forces. As a result, this part may develop a burning smell when near a hot engine. 

In case the generator is operating at too much capacity or the power cord is burned, it will also emit an unpleasant burning smell. You can rely on this sign to make an initial prediction for the generator’s condition.

The dashboard warning light appears

A glowing warning light is an indication that your charging system is having problems. On many cars, the warning light will be displayed by the check engine light. Please check the generator system before it affects surrounding components.


Will bad alternator drain the new battery?

A poor alternator can drain the battery. This condition occurs when a component in the generator fails or the connections to it.

How long will a battery last with a bad alternator?

In fact, you can drive about 25 miles with a faulty generator. Estimated time you can travel about 30 minutes. Note that you can continue to drive like this as long as the battery is fully charged and in good working order.

How can I tell if my alternator is draining my battery?

There are many signs that the alternator is causing the battery to run out of charge:

  • The noise appears
  • Dead battery
  • Can’t start the car
  • The warning light appears

What are the signs of a weak alternator?

Signs that the generator is weak:

  • Interior lights and low headlights
  • Spindle and motor stall frequently
  • The warning light appears
  • Has a burning smell

You should take your car to a service center in this case. They will assist you to check and fix the problem in the best way.

How can I prevent my car from being held by a mechanic?

To prevent your car from being held by a mechanic, you should ensure that it’s well maintained and serviced regularly. 

Regular maintenance can help identify any potential issues early on, allowing you to address them before they become major problems. It’s also essential to choose a reputable mechanic who will only keep your car if it’s genuinely unsafe to drive.


Hopefully, the article will help you answer the question: “can a bad alternator ruin a new battery?“.

Having a problem with the battery and generator will cause you a lot of difficulties. Because you will hardly be able to start the car or not be able to use the headlights and interior lights. And there will be many other limitations that you do not want it to happen to you.

Therefore, the best way is to take your car to the car service center. They will assist you to check and give you the best solution.

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