How To Tell If You Have Bad Alternator Or Spoilt Battery In Your Truck

Do you know how to differentiate an issue of a bad alternator or spoilt battery? The battery and the alternator are integral parts of a truck’s electrical system. They depend on each other for effective functioning. If your truck is not starting or cannot run the battery or alternator might be faulty. Keep reading to learn the signs and symptoms and to know whether you have a bad alternator or spoilt battery. 

A faulty alternator or battery can interfere with your schedule and drain your wallet, and it is thus essential to know some signs they exhibit when they start going bad. Initially, it is difficult to differentiate the signs of a bad alternator or spoilt battery. Still, as long as you know what you are looking for, troubleshooting is fine. 

Knowing Whether You Have A Bad Alternator Or Spoilt Battery

By the end of the guide below, you will be able to know whether you have a bad alternator or a spoilt battery in your vehicle. This will in turn help you make an informed decision.

Symptoms Of a Faulty Battery

A standard truck battery will only offer 3-5 years of service, after which it might stop functioning anytime. Many things can drain your truck’s battery. Being without power or charging for a long duration or experiencing extreme seasons can reduce the life span of your battery. A dead battery is stressful, and you can be stranded if you cannot start your truck. Here are the common signs you should watch out for. 

  • Clicking sound whenever you try to ignite and start your truck’s engine.
  • Slow cranking that might sound “rurr, rurr, rurr” when starting your truck.
  • The appearance of the engine check or battery check light on your dashboard.
  • Battery casing swelling or bloating.
  • A smell of a rotten egg or sulfur is a sign of a leaking battery.

If you have tested and are sure that your battery is in perfect condition, but your engine is still struggling, consider checking the wires and the terminals and cleaning them to remove any corrosion that might hinder power flow.

Symptoms Of A Faulty Alternator

Alternators usually have a longer lifespan than batteries, but exposure to excess heat, load, and water can facilitate their wear out. You will get stranded when you have a bad alternator or spoilt battery.

If your truck’s alternator stops functioning, the electrical demand will be catered for by the battery, which will drain. Once the battery is empty, your truck will shut off even on the highway. You can prevent this by noticing signs from your truck when the alternator becomes faulty. 

  • The appearance of the battery check-light on the dashboard.
  • If your truck has a vault gauge, its reading might be high or low.
  • The battery dies more often.
  • Dim or extremely bright lights.
  • Malfunctioning truck accessories like windows, radio, and seat warmers.
  • Grinding, growling, or whining noises under the hood. 
  • The smell of burning rubber. 


From this guide, you can easily know if you have a bad alternator or spoilt battery. Battery and alternator are essential parts of the electric system of your truck. They do not just fail abruptly, but it is a process with various signs. If you experience any of the above signs or your battery has served you for 3-5 years, consider replacing the battery or call a technician to check and replace them.