Auto Batteries – Understanding Auto Battery Testing

    Published: 06-16-2009
    Views: 17,824
    Learn how to test your battery so you don’t get stuck on the side of the road.

    John Nielsen: Hi! I'm John Nielsen with AAA's Approved Auto Repair. We don't often think about our battery until it leaves us stranded, but with a little bit of maintenance we can prevent some of those unpleasant surprises.

    Now battery testing is something that we can do to check not only the condition of our battery right now, but actually start to look at its overall state of health and give an idea of how much longer it might last.

    The most basic test is simply to check the voltage in the battery, so with the car not running the battery voltage should be above 12.

    2 Volt in a normal system. And may be a step above that would be to check this specific gravity of the electrolyte inside the battery. We can only do this on batteries that allow us to add water and top them all.

    So maintenance-free batteries just won't work, but if you remove the tops and check each of the six cells with a hydrometer and compare it to the proper readings you'll know the state of charge of each individual cell, and that can give you some idea of the overall state of health.

    But a better test for batteries is the modern testers that we use that can actually check not only the voltage and the condition but can start to look at how sulfated the battery plates are, and just the general condition of the battery. So they can tell you if it's in good shape now, and approximately how much life is left.

    Now to do this it takes a fairly expensive tester. They'll hookup to the positive and negative post, and actually run in automated test. It seems pretty simple but chemicals inside this system and the computer programs are pretty advanced and can give you a great idea of how much battery life is left.

    Now a good rule of thumb is in the southern climates where your climate is usually warm, batteries are going to last 3, 3.

    5, 4 years. So if you're living in a very hot environment, start having your battery tested about three years. In the moderate, in northern climates a good rule of thumb is to check it about four years. You can have the test run at a repair shop or if you're a AAA member you can call AAA and have come out and test your battery for you at no charge in most areas. So thinking about our battery every once in a while and having it tested can actually prevent some of those unpleasant surprises.

    Videos in this Series