Car batteries are an essential component of a car's engine, yet most of the time they shouldn't need much thought. However, when you're working on a car's battery there are three risks to safeguard yourself against:
The solution of sulfuric acid inside a lead-acid battery is normally not dangerous. It is can be used safely as an electrolyte to cause the reaction inside the battery - but if it is spilled on your hands, it is essential to wash it off immediately.
The real risk of burns comes from build-up of acid on the battery terminals. It is important that you use baking soda to neutralize the powdery sulfates that build up there and to avoid getting it on your skin – if you do, then wash it off immediately to prevent chemical burns. Finally, always wear safety goggles to prevent acid from going into your eyes.
Electric shock is a real risk with any battery. The best way to prevent yourself from harming your body - or the engine - is to disconnect the battery before working on the engine and be sure to always disconnect the positive terminal first.
You should also know to avoid being shock when you connect a battery to another battery (again - positive terminals first, followed by negative terminals).
Batteries don't normally explode – but they can if too much hydrogen gets caught inside them. To prevent this, do not smoke near a battery, learn to disconnect a battery properly to prevent an electric shock from sparking an explosion, and make sure you always work on a battery in a well-ventilated area.