It's important to test a battery for faults if one notices any of the following symptoms: 1. Physical issues:Look for signs of leaking, overheating, broken terminals, or bulging. 2. Inability to hold charge:If the battery can't maintain its charge, it may be faulty. 3. Rapid charge and quick drain: If the battery charges to 100% very quickly but th. To accurately measure the instantaneous current output of a battery using a multimeter, follow these steps: 1. Prepare the battery and multimeter:Ensure the battery is disconnected from any circuit. This is to prevent any external circuitry from affecting the measurement. 2. Set up the multimeter:Set the multimeter to measure DC current. Choose the. Car batteries are one of the most commonly checked batteries. Like any battery, a car battery can often go bad over time or fail suddenly. Even though it is more likely to happen during extreme weather, it is always a good idea to check the car battery under normal conditions too. An automotive battery measures 12.6 V or above when fully charged. W. What should a 12V battery read on a multimeter?When fully charged, a 12V battery should read slightly above 12V, for example 12.6V.