Sealed Maintenance-Free Lead-Acid Batteries for Stand-By Applications

Sealed lead acid batteries for standby applications are known with gel-technology as well as with adsorbed electrolyte (starved electrolyte system). Because of the use of Sb-free lead alloys with high hydrogen overvoltage, the electrolyte decomposition during charging is extremely low and becomes even lower during the battery-life because of an increasing oxygen-recombination. Therefore those batteries are absolutely maintenance free during their life. Especially gel type cells are free of any electrolyte stratification, which takes place during cycling of batteries with liquid electrolyte at charging potentials below the gassing voltage and which is tried to minimizeby high sophisticated systems, like air bubble-pumps. On the other hand the oxygen recombination is responsible for an anomaly in the float charge voltage in respect of a wide voltage range, which is indicated by the two possible cathodic reactions, namely the proton and the oxygen-reduction.