Signs of A Bad Car Battery vs Alternator

Signs of A Bad Car Battery vs Alternator

The battery and alternator are essential pieces of equipment to operate the engine and other electronic components of any vehicle. It helps start the engine of the vehicle and supplies power to other electrical components of the vehicle.

But sometimes the vehicle’s battery or alternator gets damaged due to some reason, due to which there are many problems in the operation of the engine or other components of the vehicle. In many cases, the vehicle’s battery is completely dead, causing all of the vehicle’s electrical components to shut down. In this article, you will learn in detail about the signs of a bad battery and alternator so that you can replace or fix your vehicle’s battery or alternator when it starts going bad.

Signs of A Bad Car Battery VS Alternator

If your car’s alternator is bad, the car engine may shut off frequently, and the main sign of a bad battery is a failure to start the engine on its own power. However, jump-starting may cause the vehicle’s engine to start. Additionally, a dead battery is unable to supply power to the vehicle’s sensors and other electrical components.

How Do Vehicle Batteries Work?

In vehicles, a battery is a rechargeable device that provides electrical energy to start the vehicle’s engine and power its electrical systems.The battery is made up of lead-acid cells, which store chemical energy and convert chemical reactions into electrical energy, providing enough voltage to the starter motor to initiate combustion in the engine. In vehicles, after the engine is started, the alternator provides power to the vehicle’s electrical components as well as recharges the battery.

Signs of A Dead Car Battery (Or Dying)

Symptoms of a dead or dead vehicle battery are slow cranking or difficult engine starting, dim or flashing headlight lights, dashboard warning lights, engine won’t start, sulfuric smell or leak, no cranking sound , or unresponsive electronic components.

Now let’s know in depth about each of these signs, so that you can change your vehicle’s battery in time and avoid the problems caused by dead or dying batteries while driving on the road.

1. Won’t Long Charging Storage

Often, a dead or dying battery is not able to store a charge for long. After fully charging the battery, it loses power within a short time. Often, it is observed that the battery works fine when the vehicle is running, but in the morning, after the vehicle is turned off overnight, the battery is unable to start the engine.

Once the engine is started by jumping the second battery, the dead battery works properly after getting charged. Therefore, not storing energy for a long time is one of the main and early signs of a dead or dying battery.

2. Engine Starting Difficulty

Oftentimes, a dead or dying battery in a vehicle can be the main cause of difficulty starting the engine. If you hear a clicking sound when you turn the key in the vehicle’s ignition but the engine does not crank, this could be a sign of a weak or dead battery. However, in many cases, it could also be an issue with a bad starter or damaged wiring. So it may be a better idea to check the wiring or starter motor first if you have difficulty starting the engine.

3. Dimming or Flickering Headlights

Dimming or flickering headlights and taillights of any vehicle can also be a sign of a dead or dying battery. Dimming or flickering lights are the result of a dead or dying battery not being able to supply enough power to the bulbs in the headlights or taillights.

However, at times, this problem can also be caused by damaged wiring, corroded terminals, or a loose ground connection. Therefore, in the case of dimming or flickering lights, the first thing to do is to check the wiring connections and the light bulb.

4. Unresponsive or Slow Performing Electronic Components

If your vehicle battery is dead or dying, you may experience other electrical issues like slow power window movement. In such a situation, the electronic components of the vehicle may perform slowly or become completely inoperative. Therefore, the main cause of unresponsive electrical components can also be a failing battery. But in many cases, a blown fuse or damaged wiring connection can also cause electrical components to be inoperable.

5 Dashboard Battery Warning Light

The dashboards of modern vehicles have several components and trouble-shooting lights that may turn on when the functioning of a related part is disrupted. So when your vehicle has a battery problem, look for a battery-shaped light or a “Check Battery” warning on your vehicle’s dashboard.

A battery warning light in the dashboard may indicate a vehicle battery problem or failure of the charging system. So, whenever the battery warning light comes on in the dashboard, check the battery and charging system.

6. Slow Engine Cranking

Often, the slow cranking of a vehicle’s engine can also be a sign of a battery problem. So when your vehicle’s battery is dying or has some other problem, you hear the engine slowly cranking. Because the dead battery is not supplying enough power to the starter motor to start the engine, the engine is slow cranking and unable to start. In many cases, it can also be an issue with a bad starter motor. So whenever there is slow cranking of the engine, make sure to check the battery or starter of your vehicle.

7. Sulfuric Odor or Leakage

In some cases, a dead or dying battery may emit a sulfuric or rotten egg smell, or you may see sulfuric acid leaking around the battery, which may appear as corrosion deposits. Therefore, a sulfuric acid smell or leak from the vehicle could be a sign of a dead or dying battery. In many cases, the problem of battery overheating or acid boiling can also be observed.

Signs Of A Bad Alternator

Symptoms of a bad alternator may be a dead or dying battery, abnormal noise, an illuminated battery warning light, dim or bright headlights, difficulty starting the engine, or frequent engine stalling.

1. Warning Battery Light

Battery signs in the cluster meter are also one of the main signs and the first signs of a bad alternator when the output supply is interrupted in case of any fault in the vehicle’s alternator. The ECU controls every function in vehicles. Whenever there is any mechanical or electrical fault in the vehicle, So the vehicle’s ECU or ECM can continuously illuminate the light related to that fault in the cluster meter. Similarly, the vehicle’s cluster meter may show the battery signal in the case of a vehicle’s alternator failure or output supply interruption.

2. Battery Dead Condition

Batteries are an important component used in vehicles, without which it is impossible to supply electric energy in the vehicle, and it is absolutely impossible for the vehicle engine to start and other electrical components to be activated.

The battery starts the vehicle’s engine and activates other sensors, and many electrical components of the vehicle are powered by the battery itself, which the battery is charged through the alternator along with the running of the vehicle. so that the energy of the battery can be kept constant.

But if any kind of fault occurs in the alternator while it is running, then the alternator will not be able to charge the battery. Due to this, the electrical components in the vehicle start consuming energy directly from the battery and in no time, the battery starts losing its energy due to a lack of charging and the battery becomes completely dead.

3. Dim or Bright Lights

The lights in the vehicle get power directly from the battery, and the headlights of any vehicle draw the most power from the battery. Due to this, the battery needs to be charged while the light is on, and the charging is done by the alternator.

But if you are driving with the headlights of the vehicle lit or even burning the headlights of the stopped vehicle and the alternator is not able to charge the battery, the headlights of the vehicle get dim after some time. Dim lights in the headlights of the vehicle can also be a sign of alternator failure, and for some reasons, the lamp’s light becomes dim or overly bright. which is caused by a bad voltage regulator in the alternator.

4. Unstable RPM Needle

An RPM meter is provided in the cluster meter of vehicles to check the RPM of the engine, which shows the reading of the crank speed of the engine. In vehicles with sensors, the RPM meter is connected to the power of the alternator to activate the operation, and when the vehicle’s alternator is badly damaged.

Then the engine’s rpm meter may stop working, or the alternator may continuously draw more or less charging power due to the faulty voltage regulator of the alternator. This can cause the needle to move up or down in the engine’s rpm meter, which could also be a sign of a bad alternator.

5. Slow-Performance Accessories

Various types of electronic accessories are used in vehicles, which are activated by the output power voltage of the battery. such as power window motors, wiper motors, ac/heat blower motors, radiator motors, radios, and many other electronic components, etc. But the battery of any vehicle can provide power to all these components only for a certain period of time, according to the capacity of its energy store, without any charging.

For consistent power performance, the battery is charged by the alternator on continuous engine starts, due to which the vehicle battery can continuously operate the electrical components in the vehicle. But if your vehicle’s alternator is damaged, and is not able to charge the battery.

So the battery will be able to use its stored energy to properly operate the electrical components for only a short period of time before, without charging, it starts dying and the electrical components and accessories installed in the vehicle slowly start performing. As you might have noticed, when the car’s battery power is low, the power window panes move slowly up and down. This could also be a sign of a bad alternator.

6. Engine Frequently Stalling

As you would know, any self start vehicle requires a battery to start. But the battery is not fully charged due to the faulty alternator in the vehicle. Due to this, whenever you turn the key in the ignition to start the engine of the vehicle, you can only hear a clicking sound instead of the rumble of the engine, and the start motor is unable to rotate the engine crank due to low battery power.

How To Know If The Alternator is Bad?

If your vehicle’s alternator is bad, you may experience symptoms associated with a bad alternator, including a battery warning light, no battery charge, frequent engine stalls, battery overcharging, unusual noises, an unstable rpm needle, or a slow or bright light. If you see these symptoms, your car’s alternator is bad, and you should have a bad alternator checked.

Can You Jump-Start A Car With A Bad Alternator?

Yes! It is possible to jump-start a car with a bad alternator, but this is only a temporary solution to the problem. Because the alternator charges the battery while the engine is running, a faulty alternator will not recharge the battery. You can jump-start the car using jumper cables or another vehicle’s jump starter, but the car’s battery will eventually run out of stored energy.

If you jump start the car and, due to a lack of charging, the car may stall again, Driving with a bad alternator can damage the battery and other systems. So get the faulty alternator and battery checked in time and get it repaired or replaced by a professional technician as needed.

How To Tell If Alternator is Draining Battery?

If you suspect your alternator is draining the battery, look for signs like dim headlights, slow power windows, and a weak or dead battery even after driving the car for a while. If you get these signs, then your vehicle’s alternator is definitely bad.

In this case, disconnect the negative battery cable while the engine is running. If the engine stalls, this indicates that the alternator is not providing power and that the engine is completely dependent on the battery. In another way, you can measure the battery voltage with a voltmeter before and after starting the engine. If the voltage drops after starting, the alternator is not charging the battery effectively. In addition, a battery warning light on the dashboard is another indication.


Q. Which is more important, the alternator or the battery?

Both the battery and the alternator are important in vehicles according to their respective functions. Because, in fact, one of the main functions of the battery in a vehicle is to start the engine. But if the alternator fails, your battery will not have enough charge to start the engine, so the dead battery will be unable to start the engine as well as supply power to other electrical components.

Q. Can an alternator fail suddenly?

Yes, alternators can fail suddenly due to a variety of factors, such as worn components, electrical problems, or wiring faults. Although some failures may occur gradually, sudden alternator failures can occur unexpectedly due to a belt break, pulley bearing damage, or a bad tensioner, leaving the vehicle without a charging system.

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