Hydrogen evolution during charging of the batteries.

During charging of the batteries, Hydrogen at the cathode and oxygen at the anode evolve. This is due to the inefficiency of the charging. This inefficiency increases with the age of the batteries. The older the battery, more is this inefficiency and more Hydrogen and oxygen evolve during the charging operation. In normal conditions, the evolved gases escape into the atmosphere whereas in the case of submarines, there is no escape of these gases. When the hydrogen concentration in the attmosphere prevalent within the submarine reaches a threshold value, there is a possibility of explaosion which is triggered by a spark. The spark can be from anywhere within that area like even rubbing of two metal parts. Hence one should be careful in using these batteries like discarding the old batteries, continously monitoring the Hydrogen concentration in the atmosphere, not charging the batteries to the full charge etc. Since the properties of the batteries differ from manufacturer to manufacturer, certain critical parameters have to be determined before use. Dr.S.Lakshminarayanan Retd. Director, Power Supply Systems DRDL / RCI (DRDO), Hyderabad