Positive charging-health checks for batteries

During the 1980s, seduced by the claims of zero maintenance, nondedicated space requirements and a design life of 10 years, more and more users of emergency power supplies switched over from traditional flooded electrolyte standby batteries to a sealed configuration. Reports from both the UK and the USA, confirmed by the author´s own experience of investigating battery failures, demonstrate a significant discrepancy between actual service life and the 10 year design life previously quoted by many battery manufacturers. Here, the author describes new commercial techniques for testing UPS secondary cells which work by measuring battery impedance-or its inverse, conductivity-by imposing a pulse or alternating-current waveform and measuring the voltage response