How To Test Car Battery? Very Easy Methods

A car battery is an essential accessory that helps start your car engine. So if your car is having starting problems, it could be because of a weak or dead battery. But before you rush out to get a new battery, you can carry out a check at home. How to test car battery is quite easy.

I will be highlighting some ways you can test your battery and also how to know if it’s dead. A dead battery might need a jump starter to get back to life. But if you find it strenuous or you can’t do this yourself, visit an auto mechanic. Most auto car shops will help test your battery at almost no cost.

How To Test Car Battery

If you find it challenging to start your car, a dead or weak battery might be the culprit. But carrying out a test is essential to be sure the fault is from the battery.  If your battery is long gone, the battery won’t hold a charge no matter how long you charge it. So long the battery cannot hold any charge, it won’t supply the power needed to start your engine. 

By using the following methods to test your car battery, you can confirm if you need to charge or replace the battery. You can carry out this test using a car battery tester/analyzer or by general observation.

Good examples of quality battery testers are

  • Multimeter
  • Otc amp battery load tester
  • Schumach 100 amp battery load tester
  • Steelman 97217 digital 12-volt battery load tester
  • Centech 100a 612v battery load tester
  • Centech 66892 battery analyzer
  • Ancel bst100 12 volt digital car battery tester
  • Foxwell bt705 car battery analyzer
  • Topdon bt500p car battery tester

Testing The Battery’s Voltage Using A Multimeter

  • Switch off the ignition and all car components
  • Set the multimeter to 20V DC
  • Place the red lead on the positive battery terminal while the black lead on the negative terminal.
  • Record your observation. A battery voltage below 12.4 might indicate replacing it with a new one.

For a better understanding, please refer to this video on how to rest a car battery voltage using a multimeter

Performing A Cranking Test Using A Multimeter

During cranking, it is easier to tell if your battery needs a charge or replacement. To do this:

  • Switch off the car, including all its accessories
  • Remove the fuel system fuse
  • The multimeter has a positive and negative lead.  Place the positive on the positive battery terminal while the negative on the negative battery terminal.
  • Ask a friend to put on the ignition for 15 seconds. Then, observe the multimeter. If the battery falls below 9.6V, it’s an indication that your battery is weak.

Note that when a car’s battery is fully charged, it should measure 12.6V and above. Then if the engine is at work, it should be around 13.7 to 14.7 volts.

Please refer to this video to better understand how to perform a crank test using a multimeter.

Increasing The Load While Testing With A Multimeter

  • Connect the positive multimeter lead to the positive car terminal, while the negative lead to the negative battery terminal
  • Ask a friend to start the car and then, observe the multimeter to see if the voltage drops below 10V. The volt will drop as you start the car, but not below 9.6 or 10 volts depending on the multimeter you use. But if it drops below 9.6 or 10, you may need to replace your battery
  • As your car starts running, the volt should increase again since the alternator starts charging the battery.  Observe the multimeter for 15 to 20 seconds; the reading should be higher than before, around 14V. If the alternator works but does not produce enough current, the battery will still fail.
  • Turn on the headlights. Even with this load, the reading should be more than 12.6 volts for the battery to work well. If the battery can’t withstand additional load such as the headlights, the battery may need a replacement; otherwise, test the alternator.

If, after the test, the battery is below 9.6V, the battery fails the test. You will either recharge the battery and start re-do the test or condemn the battery.

Kindly refer to this video for more information.

Testing The Battery Using a Load Tester

Another way you can test a battery is by using a load tester. The results are just an estimate, and the process is relatively easy. And be careful while using a load tester. The steps below highlight how to load test a car battery.

  • Get a load tester
  • Apply a load that is equal to ½ of the CCA specification of your car for 15 seconds
  • Disable the ignition
  • Using a starter motor, turn the engine over for 15 seconds

While carrying this test; the battery’s voltage shouldn’t reduce. If it does, it could be the battery isn’t holding enough charge or it’s dead. To do this, you would need a quality load tester like an oct amp battery load tester. See this video for additional information.

Testing Through Observation

If you do not have a multimeter, you can tell your battery’s voltage by testing the electrical components of your vehicle. The steps below highlight how to test car batteries without a multimeter or other battery testers.

  • Locate your car battery and check for physical damages. Some manufacturers place car batteries beneath the hood in the engine bay. If you’re not sure where yours is, please refer to your user manual
  • Ensure your battery’s wire connection are intact
  • Start the car by turning the key in the ignition to the accessory. The dashboard light should come on very bright. If they don’t come on, your battery may be dead. If the light appears dimmer than usual, it means your battery isn’t properly charged and may not be able to start the engine. If the dashboard light doesn’t come on, try to jump-start the car or charge the battery to ensure the vehicle runs again
  • Ask a friend to stand in front of your car, and turn on the headlights
  • Let your friend observe how the headlights behave.

If the lights are dim, it means the lights are running off the battery, and very possible that the alternator is producing little or no charge.In a case where the light brightens as you rev the engine, it means the alternator is producing charge. But in this case, when idle, it doesn’t have enough power to keep the battery adequately charged.

If, as you rev the engine, the brightness of the light remains normal and doesn’t change intensity, the alternator is working well.

If your battery is giving issues, yet the battery check test is ok, check if the battery holds a charge. It could also be that something else is discharging the battery – check for these. For better understanding, you can refer to this YouTube video

FAQs:

Q: How Do You Know If Your Car Needs A New Battery?

Replace your battery when it’s dead. So how do you know when your battery is dead? The following are signs of a dead battery

  • Engine starting slowly or not starting at all. This is because as time goes on and the battery wears, its components become less effective
  • Illumination of the battery light
  • Car lights are getting dim, including the headlights. This could happen when the car is idling, when revving your engine or while driving the car
  • Hearing a clicking sound when you turn the key in the ignition
  • Engine cranking slowly or sluggishly when you start the car
  • Engine backfiring due to Sparks
  • Hard starting unless you depress your gas pedal.
  • Aged battery
  • Corroded battery terminals
  • Radio not working
  • Windshield wipers working slowly

If you have tested the battery and diagnose the problem to be a dead battery, you may need to jumpstart the car. You can do this using a jumper cable in case of using two cars or use a jump starter when you don’t need another vehicle. If you are using a jumper cable, ensure the cable reaches the other car’s battery by parking cars close to each other.

Q: What Causes A Battery To Die Quickly?

There are many reasons car batteries don’t last. They may include

  • Leaving your lights on (interior light and headlights)
  • Exposing battery to harsh temperature (too hot or too cold temperature)
  • The battery has exceeded its lifespan. That is, the battery is too old.
  • Parking your car for a long time or driving for only a short time. The alternator charges the car battery. And the alternator can only do this when the vehicle is in use. So when you park your vehicle for long, or you have many short drives, the alternator won’t supply current to the battery. In turn, the battery dies after some time. 
  • Battery terminals are loosed or oxidized.
  • Failure from the charging system. In other words, the system responsible for charging the battery is faulty, which happens to be the alternator.
  • Parasitic draws. The parasite here could be your clock, radio, or alarm system. When the car is in motion, the alternator charges the battery. So if these parasites use the battery at this point, it won’t cause any harm. But while your car is off, these parasites still draw power from the battery. If this continues for long, it might cause your battery to die quickly.

Q: Will Autozone Install A New Battery?

Autozone will install your battery for free if you purchase it from them. However, there are specific conditions in which they may not install it. If the process requires them to remove other car components, they won’t install them. Going elsewhere may be the only option here.

Again, AutoZone might refuse installation if the battery is placed in a spot difficult to access – say under a car seat.

Q: Does Autozone Give You Money For New Battery?

Autozone does not buy old batteries. But to curb the improper disposal of batteries and other electrical materials, AutoZone helps in recycling while rewarding you as well. What do I mean? If you bring in an old battery, AutoZone will help to recycle it and give you a mechanized card worth $10 for bringing an old battery.

Again, if you decide to purchase a replacement battery from them, they will help test your old battery. If the old battery still revs, they give you a discount for replacement.

Q: Does Walmart Install Car Batteries For Free?

Walmart installs batteries for free, but only if you purchased from a Walmart store. Walmart has stores located in different places to cater to the needs of vehicle owners. But if you did not purchase the battery from a Walmart store, you will be charged a fee for the installation. 

But remember, before purchasing a battery, ensure you know the suitable battery for your car.  This also includes knowing the correct battery size to buy.

Aside from repairs, these experts also know how to test a car battery to see if it is dead.

Q: Does O’Reilly Give you Money For Old Batteries?

O’Reilly only gives a gift card worth $10 for old batteries, but only for unbroken batteries.  They collect these old batteries and recycle them. This too, they can come to your location to get them from you free of charge.

autozone battery test

Final Words

Learning how to test car battery will save you stress and help you know the health of your battery. That is, it gives you a clue as, whether your battery needs to be charged or replaced. So before you move to buy a new battery, ensure you test your old battery.

Every car has a battery suitable for it; you can check your user manual for the recommended battery or visit an auto shop. They help test for free. And if an expert finds out that your battery only needs a charge, they will charge it at no cost while you wait. Get yours tested now to know your battery’s health.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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