There are a lot of variables and considerations that can vary the outcome when your testing your battery, so it's significant to take all these variables really severely prior to actually making an attempt to get an precise indication of the condition of your car battery. Before you begin testing the battery in your car, 1st you need to get rid of the surface charge. If you don't get rid of the surface charge, it can make a bad battery look good or a good battery look as though it's bad.
To get rid of the surface charge just turn on your headlights for 15 seconds or you can let the battery sit for about 6 hours in a warm room, around 77Â° F. When you've gotten rid of surface charge you'll need to find out the battery's state of charge with a hydrometer. The proper gravity reading should be 12.65. The next step is to perform a load test on your battery to ascertain its actual condition while under load.
Performing a load test on a car battery is a diagnostic technique utilized to find out if the battery has adequate amperage to engage the starter motor and other car accessories. The battery has voltage, which is used to run these accessories when the engines not running. Batteries have 2 markings on the top of them...One is amperage and the other is cold cranking amps. When buying a battery, it must not only be the same size, but it must have adequate cold cranking amps to start the vehicle. There are Battery Tender devices that will maintain your battery to help keep it in top condition.
Testing Your Car Battery With a Load Tester.
>>>> Step 1). Connect the positive [+], [red] cable on the load tester to the positive [+] [red] terminal on your battery. Next connect the negative [-], [black] cable on the load tester to the negative [-] [black] terminal on your battery. The posts of the battery should be clearly marked the [+] positive and [-] negative.
>>>> Step 2). Make sure that the ignition switch is turned off. Press the load test button on your load tester. If the voltage falls below 12 volts, the battery must be charged first to be retested or replaced.
There's a variety of testing devices as well as Battery Tender/Maintainer devices for testing your battery and for extending its life. If you're not 100% sure how to do these tests, or you don't hace the testing tools...Take your car to a service garage to have the tests done.