Designation for the gas development in a cell while electricity is generated by chemical processes.Energy
When the batteries are sealed, only a small amount of gas is produced, which escapes through safety valves in case of overpressure. In wet batteries with higher gas development, it escapes via one or more vents and is conducted outside the engine compartment via a vent hose. On vehicles from different manufacturers, the vent openings and possibly hose outlets are also located at different points in the battery, e.g. on the right, left or both sides.
In flooded batteries, gas generation during charging is wanted, as the rising gases mix the acid and counteract acid stratification.