To check your battery voltage with any accuracy you need a multimeter tool. The multimeter measures the amount of current running through a wire under various conditions. The multimeter is not just a battery load testing tool, The multimeter is also used to test the amount of current flowing to and from the alternator and in what direction the voltage is flowing.
The multimeter is an essential tool for any car owner's garage. Without a multimeter, you are left with indications of an amperage, or current, problem. Using the multimeter properly, you can determine the amount of voltage inside your battery while at rest, during the initial starting process, and while the car is running. A multimeter also shows a defective alternator by measuring the among of voltage generated.
At Santa Maria Nissan in Santa Maria, CA, we check your battery and alternator during every oil change.