What type of gas is produced by batteries when they are charged?

When batteries, especially lead-acid batteries, are charged, they undergo a chemical reaction that can produce hydrogen gas. This occurs during the electrolysis of water, which is a byproduct of the charging process. As the battery charges, the electrolyte can break down, leading to the release of hydrogen at the negative plate and oxygen at the positive plate. However, the key gas related to caution during charging is hydrogen, which is flammable and can pose an explosion risk if not properly vented.

Understanding this phenomenon is crucial for safety protocols when dealing with battery maintenance and charging. Proper ventilation is necessary to avoid the buildup of hydrogen gas, which serves to highlight the importance of safe practices in battery operation and charging.