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Car Battery Testing & Voltage

It’s important to test your battery and electrical system regularly, not just when it’s starting to show signs of weakness. Proactively testing it (or making sure your mechanic does) twice a year will help reduce your chances of failure. Most retailers offer a simple free five minute battery test.

When Fully Charged, How Many Volts Should A Car Battery Have?

Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don’t have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights. If they are dim, that indicates the lights are running off the battery and that little or no charge is being produced by the alternator. If the lights get brighter as you rev the engine, it means the alternator is producing some current, but may not be producing enough at idle to keep the battery properly charged. If the lights have normal brightness and don’t change intensity as the engine is revved, your charging system is probably functioning normally. If you’ve been experiencing problems with your battery system and the headlight test checks out okay, you should check whether or not the battery is holding a charge, or if something on the vehicle is discharging it.

How Do You Perform A Load Test?

To pass a load test, the battery must maintain 9.6 volts at 15 seconds when tested at one-half the CCA rating and 70°F (or above). This test must be done with a true load (carbon pile) and not one of the hand-held testers that work off a conductance algorithm. The test must be run with the battery in a high state of charge. Be sure to read and follow all safety and handling instructions on the battery, this website and your battery tester. If you would like your battery tested, use our Find a Retailer for a location near you.

Car and Truck Battery Maintenance Tips

  1. Check your battery every now and then to make sure its terminal connections are clean, snug and protected from the elements. Signs of corrosion or leakage could mean that your battery is no longer operating as well as it should.
  2. Always unplug accessories and turn off lights when your car is turned off.
  3. Keep the battery in cooler places whenever possible. Heat damages batteries.
  4. Scrub corrosion from the terminals with a solution of water and baking soda.

Preventative Car Battery Maintenance

  • Secure the hold-down bar. This ensures that your battery is snugly seated and will help minimize vibration which can be detrimental to certain types of batteries.
  • Routinely test your battery to make sure it is correctly charged. This allows you to recharge your battery, if needed, to maintain its peak performance. It's important for your battery's health to get it tested twice a year to keep it at its optimal performance level.
  • Be sure to read and follow all safety and handling instructions on the battery and this website.

What is Battery Sulfation and How Do I Prevent it?

The term sulfation describes the accumulation and growth of lead sulfate crystals inside the plates when a battery is in a discharged state for an extended period of time. Sulfation begins as soon as voltage level gets too low which, in the case of a 12-volt battery, is below 12.6 volts. If the crystals are not recharged, they eventually combine to form larger crystals. These bigger crystals are harder to dissolve and recharge, and eventually they lead to battery failure by disrupting the plate structure. Sulfation decreases battery performance by blocking the chemical reaction that allows the battery to hold its charge.

Sulfation can be reversed by using a charger that has a de-sulfating mode, which will slowly dissolve the lead sulfate crystals and recharge them back to active material.

Car Batteries in Hot Summers and Cold Winters

Weather can take a toll on your battery. Learn more about how you can make sure you battery is ready for any season.

Care for your Car Battery in Hot Weather

Tip 1: Heat Affects Your Battery Life

Most people think about their car battery in the winter, but warm temperatures are actually your battery’s worst enemy. Hot weather means high temperatures under the hood, which accelerates corrosion inside the battery. It can also cause water to evaporate out of the battery’s liquid electrolyte. The result? Decreased battery capacity, a weakened ability to start an engine and, ultimately, shorter battery life.

Tip 2: Get Your Battery Tested

Make sure your battery is ready for the hot summer months. Get a free simple five-minute battery test to make sure your battery will beat the heat. Use our Find a Retailer to find a location near you for a free battery test.

Care for your Car Battery in Mild Weather

Tip 1: Test or Replace Your Battery Now

It is important to prepare your battery for the winter season during autumn. If there's any sign of the battery struggling now, the likelihood is that it'll let you down at some time during the winter, particularly if you have an older battery. It makes sense to test or replace your battery now to avoid the hassle of an unplanned failure in the winter.

Tip 2: Check the Battery & Charging System

Cold weather during autumn is hard on batteries, so it’s wise to check the battery and charging system. Keep the battery connections clean, tight and corrosion-free. Batteries don’t always give warning signs before they fail; it is advisable to get a battery test before winter. Use our Find a Retailer to find a location near you for a free battery test.

Tip 3: Keep Battery Connections Clean, Tight, and Corrosion-Free

During autumn, weather temperatures can be unpredictable with unexpected high heat, flooding, and early snowfall. Battery preparation for the unexpected is the best thing you can do. Check your battery before the winter season starts. Keep the battery connections clean, tight and corrosion-free. Also, when handling a battery, it is important to follow safety precautions.

Care for your Vehicle Battery in Cold Weather

Tip 1: Prepare Your Battery For Winter

Your battery has a tough job during the cold winter months. Your vehicle’s engine requires more power to start when the temperatures are colder and those temperatures make it harder for your battery to provide power.

Before winter gets an icy grip on your battery, have your electrical system tested, including your battery and alternator. Also, check the battery using a voltmeter to make sure it’s in good condition. Your voltmeter should read 12.4 volts or higher. Keep the battery fully charged throughout the winter using a battery charger or maintainer, especially if you make frequent short drives (less than a mile). Use our Find a Retailer to find a location near you for a free battery test.

Tip 2: Check Car Battery Connections

It’s important to properly maintain the components around your battery too. Make sure cables, posts and fasteners are in good shape, and check battery connections to confirm they are clean and tight. Use a stiff wire brush to clean off any corrosion and secure the battery to the battery tray to prevent excessive vibration.

Maintain Your Car or Truck Battery in Storage

The most important consideration when storing any battery is to make sure the voltage never drops below 12.4 volts. Following these simple tips on battery maintenance can help extend the life of your battery.

If you are storing the battery for an extended period of time, one of the best ways to prevent damage is to make sure the voltage never drops below 12.4 volts. We recommend using a type of "battery maintainer" – a device that will monitor your battery and keep it at full potential during storage. There are two types of maintenance chargers:

  1. Traditional "float" chargers, which provide constant voltage with tapering amperage to the battery even when it is fully charged. The typical floating charging voltage ranges from 13.0 to 13.8 volts.
  2. Fully automatic multistage or multistep chargers, which monitor the battery and charge it as necessary. Multistage maintainers will charge at varying voltages and varying amperage. Some of these multistep chargers are also capable of working well as battery chargers.

If it is not possible to use a maintenance charger, disconnect the battery from the vehicle during storage to prevent the vehicle from discharging the battery. Always provide a full charge with a battery charger prior to storage, then check the battery voltage every three to six months and charge if it falls below 12.4 volts. Also, when possible, store your battery in a cool, dry location.