Field experiences with VRLA-gel-batteries in stationary applications over a period of more than 20 years

VRLA batteries have been used in standby and telecom applications for over 20 years. Over the years there have been many papers reporting on the successes of and problems with AGM batteries but there have been far fewer papers dealing with VRLA batteries incorporating gel technology. The fact of the matter is that gel technology VRLA batteries have been used in standby applications in: small monoblocs for 35 years; medium monoblocs for telecom for 15 years; and large size single cells for 22 years. A substantial amount of statistical data on field experiences with these gel batteries is available. This paper reports in detail on: statistical data on problem reports from the field; tear down analysis; and failure modes and the main failure events. The paper provides insights into the products and process. It is believed that the paper will be a reference for the battery industry for future product development efforts.