Is it safe to smoke when checking battery fluid levels?

Smoking when checking battery fluid levels is not safe and poses significant risks. The correct understanding is that batteries, especially lead-acid types commonly used in vehicles, can emit hydrogen gas as a byproduct of the chemical reaction involved in their charging and discharging. This hydrogen gas is highly flammable and can explode if ignited.

When checking the fluid levels, there is a danger of creating a spark or flame, particularly in an enclosed space where gas can accumulate. Therefore, the practice of smoking while working with batteries, regardless of the environment or conditions, is ill-advised. The safest approach is to avoid any sources of ignition, including smoking, while actively working with batteries to prevent accidents related to flammable gases.