Few things are more irritating than getting into your car, buckling up and turning the key — only to be met with the dreaded click, click of a dead battery. A failing car battery doesn’t just disrupt your day, it can leave you stranded.
By regularly testing and maintaining your battery, you can avoid unexpected breakdowns and extend its lifespan. In this blog post, we’ll walk you through a step-by-step guide on how to check your car battery health using a voltmeter, multimeter or no tools at all. We’ll also explain how to interpret battery testing results and when it is time to replace your battery.
Why Test Your Car Battery?
Whether you suspect your battery is on its way out or you’re curious about how much life is left in it, testing your car battery can:
- Prevent unexpected breakdowns. Regular testing will help you identify a weak or failing battery before it leaves you stranded.
- Extend lifespan. The average lifespan for a conventional automotive battery is three to five years. A battery test can detect any issues early and allow you to address them, prolonging the battery’s life.
- Maintain vehicle performance. Your battery supports all the electrical systems in your vehicle. Making sure it’s healthy and up to the task keeps your car running at peak performance.
Step 1: Prepare Your Battery for Testing
Start by parking in a safe place and turning the car off. The engine should be cool before you pop the hood. Before you test the battery, make sure to inspect it for damage, like cracks or bulges. If the battery is visibly damaged don’t test it, it will need to be replaced.
If you notice corrosion, clean that off using fine-grit sandpaper or a wire brush and baking soda paste. You’ll also want to gather essential safety gear like gloves and safety glasses.
Step 2: Test Your Car Battery
There are several different options for testing your car battery. Some require battery testing tools while others can be done without any additional equipment.
Testing a Battery With a Voltmeter
A voltmeter is a tool for measuring the voltage of a car battery. It's specifically designed to gauge the electrical potential difference between two points in a circuit, making it ideal for assessing your battery's charge level. Voltmeters are available at most automotive and home improvement shops and online. Here’s how to test your car battery with a voltmeter after your car is prepped and the battery is clean:
- Set the voltmeter. Adjust the voltmeter to the DC voltage setting.
- Connect the tester. Connect the positive, red probe of the voltmeter to the positive terminal on the battery. Connect the negative, black probe to the negative terminal.
- Get your reading. Check the reading on the screen. It should be between 12.2 and 12.6 volts for a 12-volt battery. If the reading is lower than 12.2, you will need to recharge the battery with a compatible battery charger.
Testing a Battery With a Multimeter
A multimeter is another tool that’s readily available to test your car’s battery; the difference is it offers a bit more information. A voltmeter measures voltage, while a multimeter measures multiple electrical quantities, including voltage, current and resistance. To test a battery with a multimeter:
- Set the multimeter. Choose the 20-volt setting on the multimeter.
- Attach the probes. Attach the red probe to the positive battery terminal and the black probe to the negative battery terminal.
- Get your reading. A reading will appear on the multimeter’s screen, showing the battery’s resting voltage. An ideal reading is between 12.2 to 12.6 volts. If the reading is lower than 12.2 volts, the battery is weak or could be dying. It may just need to be recharged or could need a complete replacement.
Step 3: Interpret the Results
- 12.6 volts or higher. Your battery is fully charged and in good condition.
- 12.5 to 12.4 volts. Your battery is between 80% and 90% charged. Consider recharging the battery.
- 12.3 to 12.2 volts. Your car is between 50% and 75% charged. The battery may struggle to start your car, especially in cold weather. You should recharge the battery with a compatible charger as soon as possible.
- Below 12.0 volts. Your battery is significantly discharged and may be nearing the end of its usable life. Even after recharging, it might not hold a charge. Consider testing it further or replacing it.
Step 4: Charge or Replace the Battery
If your battery is reading at 12.6 volts, no action is required; you have a healthy battery. Anything below this number, though, and you’ll want to take steps to bring it back up to charge.
- Start by charging the battery with a compatible battery charger. While you might be tempted to hop in and let the alternator do the charging work while you drive, this isn’t the most efficient or effective way to charge a drained battery.
- Retest after charging. Once the battery is fully charged, retest it. If the voltage is still low, your battery may be nearing the end of its life and need to be replaced soon.
- Check for other issues. If your battery keeps dying even after being charged, there may be other electrical issues at play. Check for any electrical components that may be draining power when the car is off, alternator problems that prevent the battery from recharging as you drive, or corrosion around the terminals that can hinder electrical flow.
How to Test Your Battery Without a Meter
If you don’t have access to a voltmeter or a multimeter, you can still get a sense of the battery condition. Here’s how:
Step 1: Park your car in a safe space and turn off the engine.
Step 2: Turn on the headlights.
Step 3: Ask a friend to start the car while you observe from outside the vehicle.
Step 4: Watch the headlights as the engine turns over. If you notice a dip in brightness as the car starts up, your battery may not have enough charge.
If you see a dip in headlight brightness, either follow up with a metered test or take your car into the nearest battery testing location for a full workup.
When to Replace Your Battery
If your voltage reading is well below the standard 12.6 volts and it does not improve after a full cycle on the battery charger, it is likely time to replace your battery.
Bring your battery to your nearest Continental Battery Systems location, and we will test it and evaluate whether it can be refurbished or needs to be replaced. We can get you set up with a new automotive battery and send the spent one off for recycling.
