What does wet-cell battery gassing mean?
C.M., via e-mail Gassing is the process whereby hydrogen is given off at the negative plates and oxygen is given off at the positive plates during battery charging. To explain how this happens, let’s first look at what takes place when a load is put on a typical 12-volt wet-cell battery. As the battery discharges, lead in the positive plates combines with sulfate in the sulfuric acid electrolyte to form lead sulfate. Oxygen, also present in the active material that makes up the positive plates, combines with the hydrogen in the electrolyte to form water. A similar reaction happens on the negative plates (also known as sponge lead plates), and as the amount of lead sulfate on the plates increases, so does the water in the electrolyte. The combination of decreased active material with weakened electrolyte results in a discharged battery that can no longer produce sufficient enough current to power the load. During charging, as illustrated in the accompanying diagram, the input voltage dr
