The thermal behaviour of VRLA/AGM cells and monoblocs

摘要

VRLA/AGM cells and monoblocs were investigated concerning parameters influencing the onset of thermal runaway conditions. For this purpose 2V 1000Ah and 2V 300Ah cells were specially assembled so to include electrolyte starvation conditions similar to service life dry-out. Key cell performance parameters determined experimentally indicate that also large VRLA/AGM cells show a stable behaviour in increased temperature environments. When however dry-out or electrolyte volume level reductions of >15% are experienced, then unfavourable environmental conditions could cause a slow but steady escalation of the cell float current. The trapping of the current generated heat within the cell may yield thermal runaway conditons. The monitoring of the temperature differential "cell case - surrounding air temperature" could give a warning signal of unsafe thermal conditions to the battery plant operator.