How to Test a Car Battery

how to test a car battery

Before Testing a Car Battery

  1. Before learning how to test your battery, make sure all the lights inside your car have been turned off
  2. Disconnect all devices that might use the battery even when the car is off. Examples include dash cams, USB chargers, and other third-party electronics.
  3. Locate and check the car battery terminals (the metal bolts on the battery where you would normally clip the jumper cables) to see if they are either loose or corroded. Either one of these instances could prevent proper circulation of electrical charge and give you false readings or prevent proper charging

How to Test a Car Battery with a Multimeter

Testing with a multimeter is fairly simple. For those who have never used one before, do not be overwhelmed by all the options and symbols on the meter as we only need one of them. 

  1. What we want the dial to be set the DC voltage to 20, which is usually indicated with a solid line and a dashed line above a letter V
  2. Connect the positive probe of the multimeter with the positive terminal of the battery (red to red)
  3. Simultaneously do the same with the negative probe of the meter with the negative terminal (black to black) 

Interpret the results

If your voltage is reading at 12.6V it is sufficiently charged and your battery is in good condition. If it is reading at 12.2V it means the battery is only holding half the charge and anything lower 12V means it has discharged or is under 25% of the full charge. It is recommended to charge the battery if the voltage is under 12.45V or under 75% of it’s full charge.     

How to Test a Car Battery Without a Multimeter

There are also ways to check if your car battery is the issue without a multimeter. If your car still starts and you just want to check on the health of your battery, perform a load test

  1. Turn your headlights on without starting the engine
  2. Leave them on for 15-20 minutes
  3. Start your engine and watch for the brightness of your headlights

Your battery should be able to hold enough charge without the engine to keep your headlights on for 20 minutes. If your headlights start to dim before the engine fully starts, your battery fails the load test and you should consider replacing the battery before it fails you on the road!  

If your car is not starting at all, perform the click test

  • You would ideally want to hear multiple clicks when trying to start the car or no clicks at all. 
  • Multiple clicks mean the battery still has some power but not enough to start the car and no clicks mean the battery is completely dead.
  • Hearing just one click often entails more problems with the starter itself rather than the battery

Having your car not starting when it was completely fine the day before is one of the most dreadful feelings a driver can experience. The first thing that usually comes to mind is panic and worry that hundreds of dollars will be spent on repairs. I have personally experienced this one too many times and have learned from the past to routinely check the car battery since it, more often than not, will be the source of your troubles. Now the easiest and most sure-fire way to check and test a car battery is to get yourself a multimeter. However, even if you do not have one there are still ways and methods to check if the battery is the cause of your car not starting.