Sometimes you can just judge the battery by only looking at it. If you see any broken terminal, it means the car battery is going bad. Some things like bumping battery case, loose terminals of the battery or a short circuit are cases of bad battery.
Otherwise you can check the battery using the voltemeter test. Connect the voltmeter with the terminals of your car battery and check the reading. If the voltage comes less than 11.0 V, then there is a chance that your battery had a short circuit.