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Faulty Car Battery Symptoms – Here’s What You Need To Know

Faulty Car Battery Symptoms – Here’s What You Need To Know

To determine the main faulty car battery symptoms in your vehicle, you need to know a few important aspects of your vehicle. Knowing what the car battery is, the car battery’s function, the main reasons behind the weak car battery symptoms, and the parts that could cause this issue in your car are important to your vehicle’s diagnosis!

Auto Repairs Are EXPENSIVE

Car Battery Function


The‌ ‌car‌ ‌battery‌ ‌provides‌ ‌the‌ ‌necessary‌ ‌electricity‌ ‌to‌ ‌power‌  ‌the‌ ‌electrical‌ ‌components‌ ‌within‌ ‌your‌ ‌vehicle.‌ ‌Without‌ ‌the‌ ‌‌battery‌ ‌power‌‌ ‌from‌ ‌the‌ ‌car’s‌ ‌internal‌ ‌battery,‌ ‌no‌ ‌electrical‌ ‌component‌ ‌will‌ ‌work,‌ ‌like‌ ‌the‌ ‌lights,‌ ‌dashboard‌ ‌lights,‌ ‌or‌ ‌power‌ ‌windows.‌ If you realize your internal parts are not getting the necessary power to run at the right level, you need to look into the most common faulty car battery symptoms. ‌ ‌


The‌ ‌chemical‌ ‌reaction‌ ‌occurs‌ ‌in‌ ‌the‌ ‌battery‌ ‌system,‌ ‌transforming‌ ‌the‌ ‌chemical‌ ‌energy‌ ‌into‌ ‌

the‌ ‌electrical‌ ‌energy‌ ‌necessary‌ ‌to‌ ‌deliver‌ ‌the‌ ‌right‌ ‌amperage‌ ‌of‌ ‌voltage‌ ‌to‌ ‌the‌ ‌starter.‌ ‌In‌ ‌

addition,‌ ‌the‌ ‌battery‌ ‌stabilizes‌ ‌the‌ ‌voltage‌ ‌to‌ ‌keep‌ ‌your‌ ‌engine‌ ‌running.‌ ‌


Without‌ ‌the‌ ‌battery,‌ ‌the‌ ‌car‌ ‌would‌ ‌not‌ ‌have‌ ‌the‌ ‌energy‌ ‌required‌ ‌to‌ ‌start‌ ‌and‌ ‌maintain‌ ‌the‌ ‌power‌ ‌to‌ ‌run‌ ‌your‌ ‌vehicle.‌ If the faulty car battery symptoms prevent your car from giving the right amperage of voltage, you need to bring your car to a mechanic as soon as you can. Noticing the signs and symptoms of the weak car battery like a car owner can help you give your mechanic information that is necessary to diagnose and fix your vehicle.  ‌

Faulty Car Battery Symptoms 


Although some signs of a faulty car battery symptoms are similar to that of a damaged alternator, some distinct differences can help you when troubleshooting and diagnosing the symptoms you are experiencing in your vehicle. Knowing the signs of faulty car battery symptoms can help you prevent this issue from getting any worse in your car. 


  • Dim Headlights


If you find that your headlights are dim all of the time and do not get any brighter when you rev your engine, this is due to a dying battery that will soon be completely dead. When analyzing the signs of faulty car battery symptoms, in this situation, the lights will not get any brighter after you drive your car and will stay at a suboptimal brightness for the entire drive.


Causes of Dim Headlights

  • Corroded ground wire – one of the most common causes of dim headlights and faulty car battery symptoms are ground wires that have become corroded or rusted over time, due to the build-up of debris, disrupting the flow of electricity. 
  • Discoloring deposits – Over time, gas within the halogen bulb inside of your car can create a discoloring film that builds upon the inside of the bulb, causing lower lights and faulty car battery symptoms.
  • Loose alternator belt – dimming lights can be a sign of a faulty alternator belt, meaning that the loose connection can cause it to slip and fail to grab. 



  • Key Clicking Sound


When looking at the symptoms of a faulty car battery, clicking sounds while you turn the key in the ignition is a sure sign of your vehicle’s battery issues. When you turn the key, the battery sends an electrical current to the starter solenoid to power up the vehicle. If the battery is dead, the solenoid will not receive the signal, and the starter will have less power to run the car.

Causes of Key Clicking Sound

  • Damaged Alternator –  The car won’t be able to start if the alternator can’t provide enough voltage output necessary, with the only solution being to fix or replace the alternator. The alternator plays a key role in turning on the vehicle, so if your alternator is broken or damaged, your car will not work at the required performance level. 
  • Starter Motor – The starter motor might not be receiving enough power to turn on the car properly and efficiently. The starter motor works together with the ignition to quickly and efficiently turn on the vehicle without any problems. If the starter is not working correctly, then the motor can cause clicking noises. 
  • Corroded battery terminals – if your battery terminals are filled with dust, debris, and rust build-up, this can lead to the terminals having a green or blue buildup and a lack of connectivity. To fix this, you need to clean the terminals to restore the power supply and prevent the faulty car battery symptoms. 
  • Loose battery cables – if you have a frayed wire, loose battery cable ends, or disconnected wires, this could prevent the car from starting and cause the faulty car battery symptoms. The loose battery cables can cause the car to not turn on quickly and effectively. 



  • Slow Cranking


Slow-cranking is usually the warning sign that your car is about to die. If you notice this sign in your car when looking at the signs of faulty car battery symptoms, this is a vital sign that your car battery is almost dead and needs to be repaired or replaced before your car dies completely.

Broken ECU

The ECU is your car’s computer in charge of the various systems and functions, ensuring your vehicle runs smoothly. This engine control module controls actuators on the internal combustion engine to ensure the engine is running correctly. If there is an issue with your car’s ECU, you can lose power in your car and cause faulty car battery symptoms. 

Low Octane

If you know what detonation knock is, this could cause faulty car battery symptoms. If your engine is running smoothly, the air and fuel mixture burns evenly. However, a detonation knock can occur if the air and fuel mixture is detonating at the wrong time. Parts of the mixture can ignite too early, leading to the engine cranking and the faulty car battery symptoms. 


  • Engine Misfiring


Luckily for you and most drivers, this is a warning sign that is nearly impossible to miss. When researching the signs of a faulty car battery, this is a sign that you can directly attribute to a dying battery. Faulty car battery symptoms can cause intermittent sparks, leading to fuel build-up within the cylinders and causing engine backfiring. 


Even with the misfire, your car will still be able to run and function, but you might notice that the performance is subpar and leads to jerking while accelerating and problems with smooth driving. Diagnosing the cylinder misfire causes can reduce any performance issues and faulty car battery symptoms. 

How To Determine if it is a Faulty Car Battery vs. Alternator


When figuring out if the signs of a faulty car battery symptoms vs. alternator originate from what exact part in your car, you need to follow two key steps to analyze and diagnose the problem.


  • Check the battery


The first step in determining where the problem is coming from in your car is to check the battery. Sometimes it depends on what environment you live in – if you live in cold weather, the battery is susceptible to dying and not starting in cold weather. You can determine if this is a sign of faulty car battery symptoms by checking the dashboard’s battery gauge.


After this, check the connections, like the electrical components and the brake lights, and clean any corrosion to see if that has caused a contaminated battery. If the battery still has not started, check the battery with a voltmeter to determine the reading. If the reading is not optimal, you might be looking at the battery as the culprit when determining the faulty car battery symptoms. 


  • Check the alternator



If you find that the battery is working correctly, then the next step is to test the alternator to ensure it can start the battery at the right time. You can do this by running your car and unplugging the positive connection of the battery. At this point, if your car stops, you have a problem with the alternator. In this situation, when looking at faulty car battery symptoms when compared to the alternator, you have discovered that the alternator is at fault.

Alternator Replacement Price 

To fix your faulty car battery symptoms, sometimes you need to fix other parts as well – like the alternator. The average price to replace an alternator with a remanufactured part is approximately $400. A remanufactured alternator on a domestic car ranges from $300-$500, including the parts and labor/time required to install it. A new alternator’s price can be a lot pricier, ranging from about $500-$1,000, including the labor to install.



By looking and analyzing the faulty car battery symptoms, you need to know the difference between bad battery signs and bad alternator signs. Knowing the differences can prevent unwanted effects, like the engine misfiring, slow engine cranking, key clicking sound, and a dead battery.